Writing in the air: Facilitative effects of finger writing in older adults

Yoshihiro Itaguchi; Chiharu Yamada; Kazuyoshi Fukuzawa

doi:10.1371/journal.pone.0226832

. 2019 Dec 27;14(12):e0226832. doi: 10.1371/journal.pone.0226832

Writing in the air: Facilitative effects of finger writing in older adults

Yoshihiro Itaguchi ^1,^*, Chiharu Yamada ^2,^#, Kazuyoshi Fukuzawa ^2,^#

Editor: Emmanuel Manalo³

PMCID: PMC6934278 PMID: 31881067

Abstract

Kūsho, which refers to a behavior in which one moves the index finger as a substitute for a pen in the air or on a surface, mostly used when trying to recall the shape of a written character or the spelling of a word, has been known to facilitate cognitive task performance among kanji writing-system users. This study investigates whether the facilitative effect of kūsho, the existence of which has been exclusively confirmed in younger adults, is present in old age. Moreover, to further understand the interaction between finger movement and cognitive processing, we analyzed the correlation between the kūsho effect and factors such as age, mini-mental state examination (MMSE) score, and number of years of education. The kūsho effect was assessed by a task where participants mentally assembled a set of kanji subparts to form an actual character. The results showed a significant facilitative effect of kūsho and a strong negative correlation between kūsho effect and education. This study confirms the benefits of finger movement for solving cognitive tasks involving visual processing of written language among older adults and suggests the kūsho effect may be mediated by education.

Introduction

Aging is known to influence various areas of cognitive processing such as working memory [1], cognitive flexibility [2], inhibitory function [3], semantic memory [4], and certain aspects of language [5]. The present study aimed to investigate how aging influences the facilitative effect of finger movements known as kūsho on cognitive task performance among older Japanese adults. Kūsho is a behavior in which one moves the index finger as a substitute for a pen in the air or on a surface, mostly used when trying to recall the shape of a written character or the spelling of an English word; this behavior is mainly observed among people who use a Chinese character writing system (kanji) such as Chinese and Japanese people [6–8]. Based on a sample of Japanese young adults, previous studies found that visual feedback from kūsho behavior improved cognitive task performance for recalling the shapes of characters [9, 10]. Kūsho behavior has also shown some benefits for second-language learners of Japanese [11, 12]. While kūsho behavior is widely observed among Japanese people regardless of age, no previous study has specifically confirmed the effect of kūsho behavior on cognitive processing among older adults. The present study, therefore, aimed to investigate whether the facilitative effect of kūsho behavior is observed among kanji-culture older adults as it is among younger adults, regardless of age-related changes in the sensorimotor system and cognitive functions.

We used a kanji construction task to investigate the existence of the facilitative effect of kūsho behavior in older adults. In this task, participants try to assemble three presented kanji subparts to form an actual existing kanji character [6, 9, 10]. Kanji characters usually consist of several subparts and therefore can be broken down into several units. Kūsho behavior is frequently observed among kanji-culture individuals [6, 7, 13–15]. Even in experimental settings, the spontaneous use of this behavior is widely seen among Japanese university students [6, 9]. Previous work found that participants gave more correct responses in kanji construction tasks in the condition where they engaged in kūsho behavior (kūsho condition) compared to two other experimental conditions (i.e., rest and irrelevant movement conditions), as long as the visual feedback of their finger movements was available [9, 10]. In the present study, assuming the facilitative effect of kūsho behavior exists among older adults, we likewise used the kanji construction task and expected task performance in the kūsho condition to be better than in the other conditions.

In addition, the present study also analyzed the interaction of the kūsho effect and personal factors, including age, mini-mental state examination (MMSE) score, and years of education. It has been reported that cognitive task performance among older adults is highly influenced by factors such as educational level [16–19]. Aside from Itaguchi, Yamada (10), who found no reliable relation between vocabulary score and kūsho effect among young adults, no prior study has investigated the relation between demographic factors and kūsho effect. Using a naming task, one previous study did find that phonological cues facilitated task performance more so for older adults than for young adults [20], suggesting that an alternative network might facilitate recall for individuals with cognitive decline. We thus tentatively hypothesized that individuals among whom we assume cognitive decline is underway would show larger kūsho effects. Investigating such interactions is important for possible clinical and educational application of the behavior.

Materials and methods

Participants

Twenty-seven right-handed older adults (female = 21) participated in the experiment. One participant who could not precisely follow the experimental instructions was excluded from further analysis (see the Discussion for details). The average age of the analyzed participants (n = 26) was 86.8 years old (SD = 5.9). All were attending a senior citizen center in Tokyo, and the experiment was conducted in the center. The average score on the Edinburgh handedness inventory was 93.0 (SD = 10.0). All participants preferred to use their right hand for writing and were native Japanese speakers who had completed elementary school in Japan without any apparent problems in reading and writing. We confirmed that all participants could see the visual stimuli on the display in the experimental environment.

Table 1 shows details about the participants’ age, MMSE scores, and education. The amount education in years was self-reported. An MMSE, which is a 30-point questionnaire that is used in clinical and research settings to evaluate cognitive impairment, was conducted before or after the main experiment by one of the authors using a standard protocol. For two participants, the MMSE scores were below 24, which is the standard cut-off value for healthy and mild cognitive decline. However, note that we carefully assessed whether participants had sufficient cognitive capacity to understand and follow the instructions for the experiment by checking the rationality of their verbal responses and the appropriateness of their behavior in the experiment and conversation.

Table 1. Demographic data of participants.

	Age	MMSE	Education (years)	Handedness
Average	86.8	27.4	10.7	93.0
SD	5.9	2.5	2.7	10.0
Max	98	30	16	100
Min	71	21	6	70

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For 12 of the participants, a vocabulary test known as 100 RAKAN [21], which comprises a 100-kanji-word reading, standardized based on visual and phonetic aspects of word familiarity, was also conducted to evaluate their vocabulary size. The minimum and maximum scores of the test are 0 and 100, respectively. Although we did not consider the vocabulary data in the analysis because several participants did not perform the test, the scores for these 12 participants are available in the Supporting Information.

Kanji construction task

In the kanji construction task, participants were asked to verbally identify a kanji character based on three kanji subparts presented on a computer display [6, 9, 10], which was about 50 cm away from the participants. Before stimulus presentation, a fixation cross appeared for 1 s on the center of the display. After the fixation cross disappeared, three kanji subparts, each about 6 cm × 6 cm, were presented on the center of the screen in a triangle formation (Fig 1a). The kanji parts remained on the display for 10 s, and answers were not accepted after that time. Participants were instructed to say the original character aloud into a microphone placed in front of them as soon as they came up with the answer. The verbal responses were also recorded using a portable audio recording device during the experiment to check the responses and calculate response time later.

To form the kanji characters in their minds, participants were allowed to overlap, expand, or reduce the presented subparts. In Fig 1a, for example, to make the original kanji character, one subpart was placed on the left side and horizontally compressed, and the other subparts were vertically compressed and arranged on the right side. This type of puzzle is popular in Japan (for example, they sometimes appear in TV programs, albeit without any instructions on hand or finger movements), and all participants understood the rules without difficulty. We judged a response correct when the participant’s response matched the reading of the original kanji. A response was judged incorrect when it was wrong or not given within the specified answering period. Response times were not statistically tested or discussed because participants’ voices were not always loud or clear enough to detect the onset of the responses, and the ratio of missing values was very high (31% of correct responses were missing values for response time, and 69% of the data were used to calculate response times).

We used three experimental conditions based on previous studies [9, 10] to test the facilitative effect of kūsho behavior on kanji construction task performance. In the kūsho condition, participants had to move their right index finger freely in a writing manner on a table. It is known that the kūsho effect is greater when the index finger touches a table surface than when it writes in the air [6]. Here, participants were encouraged to use kūsho behavior (finger writing) to solve the task. In the static condition, participants kept their right hand clenched on the table and were not allowed to move any fingers. In the circle-drawing condition, participants made circular motions with their right index finger on the table surface during the trial. In all conditions, the left hand always stayed clenched on the table. The static condition was taken as the control condition, which involved neither motor planning nor visually or kinematically meaningful finger movement feedback. The circle-drawing condition was introduced to eliminate the possibility that simply moving a finger while thinking would benefit task performance, under the assumption that while it involved motor planning and motion-related feedback, it was irrelevant to writing kanji characters.

Participants were instructed to turn their face away from the screen and watch their right index finger or hand in a trial to elicit the facilitative effect of kūsho behavior, since people do not always watch their finger when they are doing kūsho. If they turned their eyes away from the finger, one of the experimenters gave an instruction to watch the finger. Our previous research, using two visual conditions (eye-on-hand and eye-on-display conditions), found that the visual feedback of kūsho finger movement was key to triggering the facilitative effect of the behavior [9, 10]; that is, no benefit is derived if one does not see the finger movement (eye-on-display condition). Two experimenters watched the participants’ finger movements as well as the focus of their gaze in the experiment to confirm that they followed the instructions, one from the side and the other one from the front of the participant. Only the eye-on-hand visual condition was used because our main purpose was to demonstrate the facilitative effects of kūsho behavior and examine the interaction between the kūsho effect and personal factors.

The participants carried out 60 trials in total (20 trials × 3 conditions). The experimental condition was performed as a block, and the order of conditions was counterbalanced among participants. Before starting the main trials, participants performed several practice trials without instructions for finger and hand conditions to observe whether they spontaneously showed kūsho behavior. We then explained the experimental conditions, and the participants again performed practice several trials to ensure that they followed the instructions.

Stimulus

We used the same sets of kanji stimuli as in previous studies [9, 10], which included a total of 60 kanji characters. All selected kanji characters were broken down into three subparts (Fig 1a). Only one actual kanji character could be constructed from the three subparts (i.e., there was one correct answer for each trial). The sub-parts were placed in a unique arrangement, different from the original one so that it would not be too easy to find the correct answer. The subparts in each stimulus were always presented in the same relative position. For the three experimental conditions, three sets of kanji characters were created to have the same character properties on average in terms of familiarity, complexity, grade level learned in school, and difficulty (for further details of the stimuli, see [10]). The three sets were randomly assigned to each hand condition. All characters used in the present study are learned in primary school in Japan. We confirmed that the participants knew and were able to read the characters after the main experiment.

Analysis

To examine the effects of the hand condition, a one-way ANOVA was performed on the number of correct responses, and as a post hoc analysis, we conducted multiple comparisons using Shaffer’s method. We also calculated the partial correlation coefficients between two variables of the kūsho effect, age, MMSE score, and education. Kūsho effect was defined as the difference in the number of correct responses between the kūsho and static conditions. Partial correlation was used because it calculates the correlation coefficient between two target variables with the effects of other variables removed. To repeat the correlation analyses, we applied Bonferroni correction to control type I error probability. We analyzed four factors in the correlation analysis; thus, the total number of tests was six.

Ethics statement

This study was conducted in accordance with the principles in the Declaration of Helsinki. The study and consent procedure were approved by the Ethics Committee on Human Research of Waseda University. All participants provided their written informed consent.

Results

Facilitative effect of kūsho behavior

We should first note that all participants (26 out of 26) spontaneously showed writing movements with their index finger while thinking during the practice trials without instruction. Although these movements were not video recorded, the two experimenters agreed that kūsho behavior was evident in all observations.

The experimental results for the kanji construction tasks confirmed the beneficial effect of kūsho behavior for older adults. The average numbers of correct responses were 5.92 (SD = 3.22) in the kūsho condition, 4.42 (SD = 3.36) in the static condition, and 4.65 (SD = 3.32) in the circle-drawing condition (Fig 2). ANOVA showed the significant effect of the experimental condition (F (2, 50) = 7.22, p < .01, η_p = 0.22). Multiple comparisons using Shaffer’s correction revealed that the number of correct responses in the kūsho condition was significantly larger than in the static condition (t (25) = 4.02, p < .05, d = 0.80) and the circle-drawing condition (t (25) = 2.61, p < .05, d = 0.52). There was no statistical difference in the number of correct responses between the static and circle-drawing conditions (t (25) = 0.23, p = .58, d = 0.11). The average response times were 6.9 s (SD = 1.2) in the kūsho condition, 6.5 s (SD = 1.8) in the static condition, and 6.8 s (SD = 1.3) in the circle-drawing condition.

Fig 2 — A dot indicates the number of correct responses for a single participant in each condition. An asterisk indicates that there is a statistically significant difference in multiple comparisons with an alpha level of 5%.

Correlation analyses of the kūsho effect

Partial correlation analysis revealed that the kūsho effect was negatively correlated with years of education but not with the other two factors. Table 2 shows the partial correlation matrix. The correlation coefficients of the kūsho effect were -.11 for age (t(23) = 0.51, p = .99), -.06 for the MMSE (t(23) = 0.28, p = .99), and -0.63 for education (t(23) = 3.75, p < .05) with Bonferroni correction. Even when excluding one outlier whose age was 71, the correlation coefficients for the kūsho effect and education were still significant (r = .60, p < .05), though the correlation coefficients for the kūsho effect and age turned out to be larger (r = .38, p = .47).

Table 2. Correlation matrix for the number of correct responses in the three experimental conditions and personal factors.

	Experimental conditions			Personal factors
	Kūsho	Static	Circle	Age	MMSE	Education
Kūsho	1	.83	.67	.30	.44	.15
Static		1	.80	.37	.52	.51
Circle			1	.39	.21	.34
Age				1	.03	.28
MMSE					1	.15
Education						1

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Fig 3 shows scatter plots for the three personal factors and for the kūsho effect. There is a consistent trend between the kūsho effect and education (right panel of Fig 3B) but not in the other pairs. We recognize a ceiling effect in the MMSE score (middle panel of Fig 3B) and one outlier in the scatter plot for age (left panel of Fig 3B).

As supplementary information for future reference, Table 3 shows a descriptive correlation matrix for the number of correct responses and other personal factors without statistical testing. For the current participants, we obtained mainly three results from the matrix. First, task performance among the three experimental conditions was well correlated (r = .83, r = .67, and r = .80). Second, the magnitudes of the correlation coefficients among the personal factors were relatively low in general. Third, both MMSE and education were moderately correlated with the baseline task performance (the coefficients for the static condition were r = .52 for MMSE and r = .51 for education).

Table 3. Partial correlation matrix of the kūsho effect and the other three factors (n = 25).

	Age	MMSE	Education years
Kūsho effect	-.11 (.00)	-.06 (-.08)	-.63^* (-.60*)
Age		-.01 (.11)	.04 (.38)
MMSE			.18 (.07)

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* Asterisk indicates significance of the correlation coefficient with Bonferroni correction (p < .05). MMSE: Mini-mental state examination.

Discussion

The present study mainly obtained two novel findings. First, we confirmed that kūsho behavior improved cognitive task performance that required visual processing of written language among older adults. This result is consistent with previous studies that found facilitative effects of kūsho behavior among university students [6, 9, 10]. We also observed that kūsho behavior occurred spontaneously in all participants without being given instructions. Second, by analyzing the partial correlations between the kūsho effect and demographic factors, we found a significant linear inverse relationship only between the kūsho effect and years of education. While we did not expect that only education would be related to kūsho effect, the overall results were generally consistent with the previously proposed idea that kūsho behavior has a beneficial influence on cognitive processing for written language. Such benefits could derive from lessening a cognitive burden that individuals with more education could manage without finger movement.

Facilitative kūsho effects in older adults

The present study confirmed the benefits of kūsho behavior in older adults, thus supporting our main hypothesis, while previous studies showed its benefits in young adults [9, 10]. We should note, however, that the total number of correct responses differed between previous studies and the present one (9.7 vs. 4.4, respectively, in the static condition on average). Moreover, the effect sizes for kūsho behavior were somewhat larger in the present study—Cohen’s d was 0.48 in the previous study [10] and 0.80 in the present study. Since task performance in the circle-drawing condition was lower than in the kūsho condition, the kūsho effect was not attributed to mere finger movement but specifically to writing-based finger movement. Although the present experiment did not address the effect of the visual feedback of finger movement, we observed improvements in cognitive task scores due to kūsho behavior, concurring with the idea that the visual feedback of finger movement helps cognitive processing [6, 9, 10]. Taken together with previous studies, the present results suggest that the interaction between language and sensorimotor systems for the facilitative effect of kūsho behavior is still working, at least among kanji-culture older adults.

The correlation analyses suggest that the benefits of kūsho behavior for cognitive tasks do not decline with age. The partial correlation coefficient between kūsho effect and age was -.11 at a statistically insignificant level, suggesting there might not be a consistent relation between them. Although the scatter plot in Fig 3B appears to show a negative correlation between age and kūsho effect, the shape of the plot is likely attributable to other confounding factors (in this case, years of education). In the current study, we did not control age-related variables other than MMSE scores and years of education, which reflect general cognitive ability and some intellectual factors, respectively. The present results thus imply that age-related decline in perceptual and motor performance (e.g., low-level vision processing, kinesthetic and touch sensation, and finger dexterity) does not play a critical role in the facilitative effect of kūsho. It should be noted that most participants were older than 80 (average age: 86.8), and we cannot exclude the possibility that the age range of the participants contributed to the low correlation between age and kūsho effect.

One might argue that the kūsho effect is not facilitative but inhibitory because of the tight coupling between the visual and sensorimotor representation of the characters. It is possible to assume that the “baseline” is not the static condition but the kūsho condition, and consequently the constraint on finger movement in the static condition might have an inhibitory effect, especially for individuals with lower cognitive function due to less education. While this hypothesis does not have direct evidence, it is not absurd. Previous studies and our own data have shown that, among Japanese people, kūsho behavior occurs frequently in both daily life and experimental settings without any instructions, regardless of age and time period [6, 9]. Such spontaneous kūsho behavior should be distinguished from the strategy used by pure alexia patients where they read letters or characters by tracing them, sometimes called “kinesthetic facilitation” [22–25]. However, both types of finger writing appear to stem from a tight coupling of visual representation and kinetic factors in written languages, as supported by studies in neuropsychology [26, 27] and brain imaging [28]. In line with such coupling, one participant who was excluded from the analysis in the present study (age = 81, MMSE = 22, years of education = 16) showed a strong tendency to use kūsho behavior even in the static condition—that is, even when he was not supposed to use kūsho, he could not stop moving his index finger. These observations might indicate tight coupling between finger actions and written characters [14, 29], suggesting that a large load would be required to inhibit finger movement among individuals who have acquired it as a natural habit.

Education years, MMSE score, and other possible variables for the kūsho effect

Different sizes of the kūsho effect have been found in various studies; this might be explained by the fact that participants of the studies had different years of education. In this study, we found a moderate-sized negative correlation between years of education and the kūsho effect; individuals with less education showed larger kūsho effects than those with more education. This is consistent with our previous research [10]. That is, if we simply assume education-dependent changes in kūsho effect, the different sizes of the kūsho effect between the studies (0.48 vs 0.80) can be explained without assuming age-dependent changes in the kūsho effect. The young adults in the previous study were university students, and therefore their education level was higher than that of the participants in the present study (at least 12 years, vs. 10.7 years on average). Accordingly, the kūsho effects for a participant group that includes various educational levels should be higher than those of university students.

Specific cognitive declines are likely to intervene in a larger kūsho effect, although this study did not clarify the exact factors and mechanisms that are modulated by years of education. Education level is known to positively correlate with various cognitive [17, 18, 30, 31] and brain functions [16, 32] in older adults and has also been used as a marker of the concept of cognitive reserve, which refers to susceptibility to age-related changes in cognitive functions [19, 33–35]. These previous findings together suggest that the individuals with more years of education in this study might have produced a moderate number of correct responses even in the condition where the kūsho behavior was not available, and, therefore, they benefited less from kūsho behavior than those with fewer years of education. In the present study, the MMSE scores, which reflect general cognitive decline, was not related with education or the kūsho effect, suggesting that the increase in kūsho effect was not attributed to global cognitive status, but to a decline in rather specific cognitive functions. One possible candidate to explain this could be the high level of visual processing. Previous studies have suggested that kanji construction tasks strongly activate visual areas [36] and that visual feedback from kūsho movement helps with solving tasks [9, 10]. This requires further investigation using comprehensive cognitive tests such as the WAIS-III. Another candidate may be vocabulary size; vocabulary scores are known to be positively correlated with education years [37–39]. Although vocabulary score has been suggested as not being associated with the kūsho effect in younger adults [10], there is still a possibility that it interacts with the sensorimotor processing in older populations. Kinesthetic feedback of kūsho finger movement, which was shown to have only little (non-significant) effect on task performance if visual feedback of movement is not available in younger adults [9, 10], could also contribute to the facilitation effect in older adults, as the importance of visual feedback in task processing was not directly tested in the present study. Collectively, previous findings and our data suggest that decline in a specific function may be involved with a modulation of the kūsho effect in the kanji construction task.

While this study is the first to demonstrate the beneficial effects of kūsho behavior for older adults, some limitations should be noted. First, the observed effect of kūsho behavior is quite task-specific [9]. It is thus not clarified whether kūsho effects occur with other kinds of tasks. Second, although it has been shown that visual feedback of finger movement is critical to inducing the benefits of kūsho behavior, this study used only one visual condition instead of comparing two visual conditions. Therefore, we do not have direct evidence for the importance of visual feedback for older adults. Third, the sample size and age range were relatively small in terms of generalizing the findings to the whole population. That said, the sample size was adequate for detecting a middle to large effect size (power = .70 for f² = 0.15 and power = .97 for f² = 0.35) in the ANOVA, and the correlation was reliable (r = -.63). Twenty-six older adults participated in the present experiment, and their average age was 86.8 years. Given the huge variability in the characteristics of older adults, a larger sample, one that includes younger older adults, may be needed to more firmly establish our findings.

Even with these limitations, the present results can provide some general implications. First, kūsho behavior could have clinical and educational benefits for individuals with a decline or a lack of ability in specific cognitive functions such as stroke patients and second-language learners [10]. As mentioned earlier, alexia patients can sometimes recognize words and characters by tracing them with their index finger [22–25, 27], which is essentially the same behavior as kūsho. Thomas (12) also reported that kūsho behavior improved kanji learning for second-language learners of Japanese. Our finding that the kūsho effect was negatively related to years of education also suggests that kūsho is a helpful tool, especially for individuals with a declining specific, but not general, cognitive function. Accordingly, although kūsho behavior could be beneficial for individuals with mild cognitive impairments, it may not correlate with MMSE score. Second, the kūsho effect observed in this study may provide an instantiation of embodied cognition. It has been shown that finger movement differently influences arithmetic problem solving, depending on how calculation strategies are acquired [40], and the interference of finger movement is culturally modulated [41]. Our data suggest that demographic factors such as intellectual ability and age should be included when considering the interaction between bodily movement and cognition.

Supporting information

S1 Table. Raw data obtained in the experiment.

(XLSX)

Click here for additional data file.^{(13KB, xlsx)}

Data Availability

All relevant data are within the manuscript and its Supporting Information files.

Funding Statement

Japan Society for the Promotion of Science http://dx.doi.org/10.13039/501100001691 KAKENHI 18K13372 Dr. Yoshihiro Itaguchi Japan Society for the Promotion of Science http://dx.doi.org/10.13039/501100001691 KAKENHI 18K03188 Prof. Kazuyoshi Fukuzawa The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

References

1.Lichtenberger EO, Kaufman AS. Essentials of WAIS-IV assessment: John Wiley & Sons; 2009. [Google Scholar]
2.Mayr U. Age differences in the selection of mental sets: the role of inhibition, stimulus ambiguity, and response-set overlap. Psychol Aging. 2001;16(1):96 10.1037/0882-7974.16.1.96 [DOI] [PubMed] [Google Scholar]
3.Bugg JM, DeLosh EL, Davalos DB, Davis HP. Age differences in Stroop interference: Contributions of general slowing and task-specific deficits. Aging, Neuropsychology, and Cognition. 2007;14(2):155–67. [DOI] [PubMed] [Google Scholar]
4.Verhaegen C, Poncelet M. Changes in naming and semantic abilities with aging from 50 to 90 years. J Int Neuropsychol Soc. 2013;19(2):119–26. 10.1017/S1355617712001178 [DOI] [PubMed] [Google Scholar]
5.Lindenberger U, Baltes PB. Intellectual functioning in old and very old age: cross-sectional results from the Berlin Aging Study. Psychol Aging. 1997;12(3):410 10.1037//0882-7974.12.3.410 [DOI] [PubMed] [Google Scholar]
6.Sasaki M. Why do Japanese write characters in space? International Journal of Behavioral Development. 1987;10(2):135–49. [Google Scholar]
7.Kess JF, Miyamoto T. Japanese psycholinguistics: A classified and annotated research bibliography: John Benjamins Publishing; 1994. [Google Scholar]
8.Endo Y. The role of a motoric aspect of representation: Spontaneous writing-like behavior in Japanese. Practical aspects of memory: Current research and issues. 1988;2:459–63. [Google Scholar]
9.Itaguchi Y, Yamada C, Fukuzawa K. Writing in the air: Contributions of finger movement to cognitive processing. PLoS One. 2015;10(6):e0128419 10.1371/journal.pone.0128419 [DOI] [PMC free article] [PubMed] [Google Scholar]
10.Itaguchi Y, Yamada C, Yoshihara M, Fukuzawa K. Writing in the air: A visualization tool for written languages. PLoS One. 2017;12(6):e0178735 10.1371/journal.pone.0178735 [DOI] [PMC free article] [PubMed] [Google Scholar]
11.Thomas M. "Air writing" and second language learners’ knowledge of Japanese kanji. Japanese Language and Literature. 2013:23–58. [Google Scholar]
12.Thomas M. Air writing as a technique for the acquisition of Sino‐Japanese characters by second language learners. Language Learning. 2015;65(3):631–59. [Google Scholar]
13.Kess JF, Miyamoto T. Kanji knowledge as read-only vs. write-only: The effect of the computer age. Japan in the Global Age. 2001:175–87. [Google Scholar]
14.Yim-Ng RV, Andrade Jackie, Yuet-Yee. Contribution of finger tracing to the recognition of Chinese characters. Int J Lang Commun Disord. 2000;35(4):561–71. 10.1080/136828200750001296 [DOI] [PubMed] [Google Scholar]
15.Hoosain R. Psycholinguistic implications for linguistic relativity: A case study of Chinese: Psychology Press; 1991. [Google Scholar]
16.Springer MV, McIntosh AR, Winocur G, Grady CL. The relation between brain activity during memory tasks and years of education in young and older adults. Neuropsychology. 2005;19(2):181 10.1037/0894-4105.19.2.181 [DOI] [PubMed] [Google Scholar]
17.Wilson R, Hebert L, Scherr P, Barnes L, De Leon CM, Evans D. Educational attainment and cognitive decline in old age. Neurology. 2009;72(5):460–5. 10.1212/01.wnl.0000341782.71418.6c [DOI] [PMC free article] [PubMed] [Google Scholar]
18.Colsher PL, Wallace RB. Longitudinal application of cognitive function measures in a defined population of community-dwelling elders. Ann Epidemiol. 1991;1(3):215–30. 10.1016/1047-2797(91)90001-s [DOI] [PubMed] [Google Scholar]
19.Stern Y, Albert S, Tang M-X, Tsai W-Y. Rate of memory decline in AD is related to education and occupation Cognitive reserve? Neurology. 1999;53(9):1942-. 10.1212/wnl.53.9.1942 [DOI] [PubMed] [Google Scholar]
20.Au R, Joung P, Nicholas M, Obler LK, Kass R, Albert ML. Naming ability across the adult life span. Aging, Neuropsychology, and Cognition. 1995;2(4):300–11. [Google Scholar]
21.Amano S, Kondo T, editors. Estimation of mental lexicon size with word familiarity database. ICSLP; 1998.
22.Maher LM, Clayton MC, Barrett AM, Schober-Peterson D, Rothi LJG. Rehabilitation of a case of pure alexia: Exploiting residual abilities. J Int Neuropsychol Soc. 1998;4(06):636–47. [DOI] [PubMed] [Google Scholar]
23.Dejerine J. Sur un cas de cécité verbale avec agraphie suivi d’autopsie. Mémoires de la Société de Biologie. 1891;3:197–201. [Google Scholar]
24.Goldstein K. Language and language disturbances; aphasic symptom complexes and their significance for medicine and theory of language. 1948.
25.Kashiwagi T, Kashiwagi A. Recovery process of a Japanese alexic without agraphia. Aphasiology. 1989;3(1):75–91. [Google Scholar]
26.Tanaka S, Katayama M, Ozawa T, Inui T. A case of pure alexia who can read letters by observing others’ writing action. Japanese Journal of Neuropsychology. 2002;18:68–75. [Google Scholar]
27.Bartolomeo P, Bachoud-Lévi A-C, Chokron S, Degos D. Visually-and motor-based knowledge of letters: evidence from a pure alexic patient. Neuropsychologia. 2002;40(8):1363–71. 10.1016/s0028-3932(01)00209-3 [DOI] [PubMed] [Google Scholar]
28.Longcamp M, Anton J-L, Roth M, Velay J-L. Visual presentation of single letters activates a premotor area involved in writing. Neuroimage. 2003;19(4):1492–500. 10.1016/s1053-8119(03)00088-0 [DOI] [PubMed] [Google Scholar]
29.Longcamp M, Zerbato-Poudou M-T, Velay J-L. The influence of writing practice on letter recognition in preschool children: A comparison between handwriting and typing. Acta Psychol (Amst). 2005;119(1):67–79. [DOI] [PubMed] [Google Scholar]
30.Insel K, Morrow D, Brewer B, Figueredo A. Executive function, working memory, and medication adherence among older adults. The Journals of Gerontology Series B: Psychological Sciences and Social Sciences. 2006;61(2):P102–P7. 10.1093/geronb/61.2.p102 [DOI] [PubMed] [Google Scholar]
31.Cohen RG, Sternad D. State space analysis of timing: exploiting task redundancy to reduce sensitivity to timing. J Neurophysiol. 2012;107(2):618–27. 10.1152/jn.00568.2011 [DOI] [PMC free article] [PubMed] [Google Scholar]
32.Berryhill ME, Jones KT. tDCS selectively improves working memory in older adults with more education. Neurosci Lett. 2012;521(2):148–51. 10.1016/j.neulet.2012.05.074 [DOI] [PubMed] [Google Scholar]
33.Stern Y, Gurland B, Tatemichi TK, Tang MX, Wilder D, Mayeux R. Influence of education and occupation on the incidence of Alzheimer’s disease. JAMA. 1994;271(13):1004–10. [PubMed] [Google Scholar]
34.Piccinin AM, Muniz-Terrera G, Clouston S, Reynolds CA, Thorvaldsson V, Deary IJ, et al. Coordinated analysis of age, sex, and education effects on change in MMSE scores. Journals of Gerontology Series B: Psychological Sciences and Social Sciences. 2012;68(3):374–90. [DOI] [PMC free article] [PubMed] [Google Scholar]
35.Soldan A, Pettigrew C, Albert M. Evaluating cognitive reserve through the prism of preclinical Alzheimer disease. Psychiatric Clinics. 2018;41(1):65–77. 10.1016/j.psc.2017.10.006 [DOI] [PMC free article] [PubMed] [Google Scholar]
36.Matsuo K, Kato C, Tanaka S, Sugio T, Matsuzawa M, Inui T, et al. Visual language and handwriting movement: functional magnetic resonance imaging at 3 tesla during generation of ideographic characters. Brain Res Bull. 2001;55(4):549–54. 10.1016/s0361-9230(01)00564-0 [DOI] [PubMed] [Google Scholar]
37.Verhaeghen P. Aging and vocabulary score: A meta-analysis. Psychol Aging. 2003;18(2):332 10.1037/0882-7974.18.2.332 [DOI] [PubMed] [Google Scholar]
38.Uttl B. North American Adult Reading Test: age norms, reliability, and validity. J Clin Exp Neuropsychol. 2002;24(8):1123–37. 10.1076/jcen.24.8.1123.8375 [DOI] [PubMed] [Google Scholar]
39.Kempler D, Teng EL, Dick M, Taussig IM, Davis DS. The effects of age, education, and ethnicity on verbal fluency. J Int Neuropsychol Soc. 1998;4(6):531–8. 10.1017/s1355617798466013 [DOI] [PubMed] [Google Scholar]
40.Michaux N, Masson N, Pesenti M, Andres M. Selective interference of finger movements on basic addition and subtraction problem solving. Exp Psychol. 2013;60(3):197–205. 10.1027/1618-3169/a000188 [DOI] [PubMed] [Google Scholar]
41.Bender A, Beller S. Nature and culture of finger counting: Diversity and representational effects of an embodied cognitive tool. Cognition. 2012;124(2):156–82. 10.1016/j.cognition.2012.05.005 [DOI] [PubMed] [Google Scholar]

PLoS One. doi: 10.1371/journal.pone.0226832.r001

Decision Letter 0

Emmanuel Manalo

25 Jul 2019

PONE-D-19-16768

Writing in the air: facilitative effects of finger writing in older adults

PLOS ONE

Dear Dr. Itaguchi,

Thank you for submitting your manuscript to PLOS ONE. After careful consideration, we feel that it has merit but does not fully meet PLOS ONE’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that systematically addresses all the points raised by the three reviewers during the review process (see below).

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PLOS ONE

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Comments to the Author

1. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #1: Partly

Reviewer #2: Yes

Reviewer #3: Yes

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2. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: I Don't Know

Reviewer #2: Yes

Reviewer #3: Yes

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3. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #1: No

Reviewer #2: Yes

Reviewer #3: Yes

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4. Is the manuscript presented in an intelligible fashion and written in standard English?

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Reviewer #1: Yes

Reviewer #2: Yes

Reviewer #3: Yes

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5. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: This small study reports intriguing findings, and contributes to the stream of on-going work on kūsho. The general design of the study is sound. However, to my mind it somewhat overstates its findings, and in several places leaves out critical information. Specifically:

(1) I would suggest that the abstract be revised to include greater specification of the meaning of the terms ‘kūsho’ and ‘the kūsho effect’. I showed this abstract to several colleagues who have no exposure to kanji cultures. They were wholly mystified as to the meaning of ‘writing in the air or on a surface with one’s index finger’. Unless you anticipate addressing only a readership that is already familiar with kūsho, I think you need to add to the Abstract some further identification of its meaning.

(2) Line 66: ‘Individuals with demographic factors related to cognitive decline’ is both vague and disguises an inference you are making. Can you be more straightforward? How about ‘older adults, among whom we assume cognitive decline is underway’?

(3) Line 67: This raises a major problem: from here on out you refer repeatedly to ‘larger [/ smaller] kūsho effects’. You don’t actually measure the SIZE of the effect, but rather only the frequency of its presence / absence. This comes to a head in the interpretation of Figure 3b, where the horizontal axis records the kūsho effect from –6 to (+)6. Presumably, this is not a measure of its ‘larger / smaller’ SIZE, but rather its frequency of use—correct? This needs to be clearly specified. (I would add that Figure 3 is out of focus and difficult to read. Can a new version of it be created, with higher resolution?)

(4) Line 82. Please provide full details on the content of the MMSE.

(5) Lines 83–5. Please also explain how you ‘carefully assessed whether participants had sufficient cognitive capacity…’

(6) The authors declare under ‘Data availability’ that ‘All relevant data are within the manuscript and its Supporting Information files.’ However, I would like to see the full set of 60 experimental stimuli, and do not find them in the materials made available to me in the course of this review.

(7) Line 16 mentions that ‘This type of puzzle is popular in Japan’. Could you elaborate? If kanji-assembly tasks constitute a familiar puzzle or pastime, how is that carried out? Does kūsho play any role in it—a role that might carry over into your results?

(8) Lines 130–1. How, exactly, did you ‘encourage [participants] to turn their eyes from the screen to their right index finger’? Did any participants resist doing so, fail to do so, or fail to maintain their gaze on the kūsho-producing hand?

(9) Discussion section. I think this section would benefit for a more conservative statement of your findings. For example, have you really ‘confirmed that kūsho behavior improved cognitive task performance’ as opposed to ‘confirmed that kūsho behavior co-occurs with improved cognitive task performance, relative to performance under the other two test conditions’? Likewise, have you shown that ‘kūsho behavior has a beneficial influence on cognitive processing’ as opposed to that ‘kūsho behavior correlates with greater success at integrating parts of kanji into familiar whole orthographic units’?

Similarly, in lines 330–2, the authors claim that because of the negative relation between kūsho and years of education, ‘our findings…suggest that kūsho is a helpful tool, especially for individuals with declining cognitive function’. I’m not sure you can draw that inference, rather than simply that ‘kūsho is less frequently employed by older individuals with more years of education relative to their age-mates with less education’. I don’t think you’ve shown that less education correlates with greater cognitive decline.

(10) Lines 251–8. You make the case for visual feedback as a prerequisite for the efficacy of kūsho behavior. But how do you deal with the commonly-observed spontaneous use of kūsho in settings where visual feedback is seemingly deliberately unavailable, such as writing on the top of one’s thigh underneath a desk top, or in the air with the writer’s gaze turned away from the kūsho-producing hand? And if visual feedback were necessary to induce the kūsho effect, why would you have to ‘ENCOURAGE [participants] to turn their eyes from the screen to their right index finger’ as opposed to simply relying on their spontaneous integration of visual input to the kūsho effect?

(12) As conceded in lines 318–9, the sample size is quite small. I would expect that with a larger pool of participants, the effects of age and years of education might be more fully displayed. I would recommend that the study be augmented.

There are a few typos, or sites where word choice might be improved.

Lines 22, 25: Missing definite article before ‘__ kūsho effect’

Line 22: Since the participants’ education is not assessed qualitatively or with respect to its content, I would suggest ‘…(MMSE) score, and number of years of education’

Reviewer #2: This study demonstrates the beneficial properties of “Kūsho behavior” among Japanese older adults in identifying kanji characters from disjointed units of the characters. The study was based on an earlier investigation employing the same experimental design with younger Japanese persons. The authors report two main findings of their investigation: First, the existence of a facilitatory behavior in older persons to achieve correct identification of kanji characters by deployment of Kūsho behavior and second, the negative association of this phenomenon with the educational level of the participants.

Although, these findings are mainly relevant for kanji writing-system users, it is an interesting investigation that may add new knowledge to the aging literature. However, there are some concerns that need to be addressed before the paper can be published.

1) Abstract: it needs to be rewritten after correcting the manuscript. Specifically the last sentence should be corrected. It cannot be asserted that “The study confirms the benefits of finger movement for “solving cognitive tasks….”. This study deals with the effect of “Kūsho behavior” on identification of written language/kanji characters and not with various cognitive tasks. In addition, it should be stated that: “the kūsho effect may be mediated by “education” and not by “intellectual ability”.

2) Introduction:

a. My main concern is related to the rationale of assessing the facilitative effect of “Kūsho” in older adults. The authors argue that they wish to test whether the “Kūsho” behavior is universal, regardless of age. However, if this phenomenon occurs due to the written language system, i.e., use of kanji, the phenomenon should be present on every literate person, disregarding the age of the individual. Thus, the authors do not provide a reason for why this phenomenon should not exist in older literate people. I believe that the interest to study older adults in this experimental situation is to evaluate whether “Kūsho behavior” is equally relevant for this population as it is for younger individuals. My understanding is that any literate person in the kanji-system may rely at different degrees on “Kūsho behavior”. If this is true, the reason to assess older persons is to better understand how normal age-related changes in sensorimotor systems and cognitive functions affect “Kūsho behavior”.

b. It would be a strength if the authors add information on “cognitive reserve” (CR), especially in view of their findings on education. CR is particularly important to understand age-related changes, both declines and gains, in late adulthood in any culture and to my knowledge across different languages.

c. It would be important to develop more on why vocabulary was not addressed in this investigation. It is well known that vocabulary can be highly important in determining outcomes of language studies and aging. It would be more advisable to actually add vocabulary data to this manuscript. See more comments on this issue below.

3) Methods:

a. It seems that the MMSE cut-off of 24 was not use as inclusion or exclusion criteria, which is understandable due to the advanced age of many of the participants. However, the authors claim to have examined a sample of healthy older adults. This cannot be stated since there are participants scoring below MMSE 24 who might have important cognitive declines possibly related to dementia or mild cognitive decline. This issue needs to be addressed and acknowledged.

b. It would strength the study to present data on vocabulary in case that such data are available. It would be important to show whether education, vocabulary, or both exert an effect on less deployment of Kūsho behavior in older adults.

c. Why is handedness measured and reported? The authors do not mentioned this variable in either the introduction or the discussion. If it is no of importance, it should be removed.

4) Results:

a. Related to the previous comment, it would be interesting to compare the relative importance of education vs. vocabulary. Findings would enhance the interest of the study.

5) Discussion:

a. If vocabulary data were available, it would be necessary to expand the discussion on p. 11 to cover “Educational level vs vocabulary level and Kūsho effect”.

b. This part should also be amended by including a discussion on CR and the final findings that in the best of cases comprise both education and vocabulary.

Reviewer #3: Authors have conducted a series of experiments investigating kusho behaviors. Now, they extend their target to elderly people living in Japan.

I appreciate their new contribution using elderly people. However, their research question is not clearly written in the current manuscript. For that reason, I suppose, their discussion also has not been deepened sufficiently enough.

I would point out two main negatives of this paper:

(i) No comparisons with younger participants

(ii) No further examinations of cognitive abilities specifically, memory.

I suspect that these negatives might come from the fact that they had no valid hypothesis when they started this study.

To compensate these negatives, authors should work even harder. I will try to provide them inspirations for that as follows.

Major points

(1) Motivation of the study.

I have to say that authors did not successfully explain their motivation to study elderly people. I know they stated:

While kūsho behavior is widely observed among Japanese people regardless of age, no previous study has specifically confirmed the effect of kūsho behavior on cognitive processing among older adults. The present study, therefore, aimed to investigate whether the facilitative effect of kūsho behavior is universal, regardless of age, at least among kanji-culture adults. (lines 41-44)

This does not sound intrinsic. I would like authors to more clearly ensure accountability for the employment of elderly people for this study.

I will give some suggestions regarding this point (although I do not mean to force authors to discuss these; they would achieve better than me.)

(i) What is the main influence of the aging on kusho behaviors? No effects? Reducing or amplifying?

(ii) The computer environment of elderly people when they learned kanji was greatly different from the modern one. In a sense, they evaded the use of electric devices during their childhood. Then, the kusho effects might be genuinely observed among them as compared to younger participants.

(iii) In spite of the memory decline generally seen among the elderly, the kusho movements would be stably maintained. Even more, it may facilitate the memory of kanji.

(2) Dementia and MCI

It was good that authors examined MMSE. I found by Table 1 and Figure 3 that they included participants who were categorized as MCI or even as dementia (score 21). Authors should discuss the effects of MCI/dementia on kusho.

(3) ANCOVA

I think they could use ANCOVA instead of ANOVA for their analysis, including age, MMSE score and years of education as the covariates.

(4) Paragraph writing

I would suggest that authors rewrite all paragraphs to ensure that a conclusion statement comes to the first line and then the explanations follow in the rest of the paragraph.

Minor points

(5) Lines 36-37, “kanji writing-system users”: this expression is inappropriate because Chinese speaking people do not call their character kanji. Instead, authors may just want to use “character users” or “people who use a writing system with characters”.

(6) Participants: did all participants prefer to use their right hand for writing? Authors should clearly state this point.

(7) Experimental settings: how far was the computer from a participant? How many experimenters stayed beside a participant and what locations? Authors should explain how they observed participants’ responses sufficiently.

(8) Stimuli: how did they decide the locations of subparts in the triangle? Did authors avoid a subpart to write first in the original kanji came to the top of the triangle or never mind and put it randomly?

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Reviewer #1: Yes: Margaret Thomas

Reviewer #2: No

Reviewer #3: No

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PLoS One. 2019 Dec 27;14(12):e0226832. doi: 10.1371/journal.pone.0226832.r002

Author response to Decision Letter 0

21 Aug 2019

The comments from the reviewers have been responded in an attached file.

Attachment

Submitted filename: Kusho_older_adults_Responses_to_Reviewers_20190819.docx

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PLoS One. doi: 10.1371/journal.pone.0226832.r003

Decision Letter 1

Emmanuel Manalo

23 Sep 2019

PONE-D-19-16768R1

Writing in the air: facilitative effects of finger writing in older adults

PLOS ONE

Dear Dr. Itaguchi,

All three reviewers acknowledge that you have improved the manuscript this time round. However, all three reviewers also provide point-by-point details of issues that remain unsatisfactorily resolved. Therefore, I would like you to very carefully and systematically address all those issues/points they have raised in a further revision of this manuscript.

We would appreciate receiving your revised manuscript by Nov 07 2019 11:59PM. When you are ready to submit your revision, log on to https://www.editorialmanager.com/pone/ and select the 'Submissions Needing Revision' folder to locate your manuscript file.

If you would like to make changes to your financial disclosure, please include your updated statement in your cover letter.

Please include the following items when submitting your revised manuscript:

A rebuttal letter that responds to each point raised by the academic editor and reviewer(s). This letter should be uploaded as separate file and labeled 'Response to Reviewers'.
A marked-up copy of your manuscript that highlights changes made to the original version. This file should be uploaded as separate file and labeled 'Revised Manuscript with Track Changes'.
An unmarked version of your revised paper without tracked changes. This file should be uploaded as separate file and labeled 'Manuscript'.

We look forward to receiving your revised manuscript.

Kind regards,

Emmanuel Manalo, PhD

Academic Editor

PLOS ONE

[Note: HTML markup is below. Please do not edit.]

Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. If the authors have adequately addressed your comments raised in a previous round of review and you feel that this manuscript is now acceptable for publication, you may indicate that here to bypass the “Comments to the Author” section, enter your conflict of interest statement in the “Confidential to Editor” section, and submit your "Accept" recommendation.

Reviewer #1: (No Response)

Reviewer #2: All comments have been addressed

Reviewer #3: (No Response)

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2. Is the manuscript technically sound, and do the data support the conclusions?

Reviewer #1: Partly

Reviewer #2: Yes

Reviewer #3: Yes

**********

3. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: I Don't Know

Reviewer #2: Yes

Reviewer #3: Yes

**********

4. Have the authors made all data underlying the findings in their manuscript fully available?

Reviewer #1: Yes

Reviewer #2: Yes

Reviewer #3: No

**********

5. Is the manuscript presented in an intelligible fashion and written in standard English?

Reviewer #1: Yes

Reviewer #2: Yes

Reviewer #3: No

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6. Review Comments to the Author

Reviewer #1: The revisions of this ms. raise its quality, but feel a bit superficial. My objections number (10) is smoothed over without really resolving it; (11) is sidestepped; and most of the rest appropriately dealt with. However, I don't think the authors have really dealt with a matter raised by Reviewers #2 and #3 , "No comparison with a younger cohort". Do Reviewers #2 & #3 feel that this has been adequately addressed? If so, I would reluctantly shift my assessment to "Accept".

Reviewer #2: The authors reasonably addressed my previous concerns and they have now delivered a much improved manuscript. However, there are still some minor points that need to be corrected:

1. In the abstract, I suggest to better clarify the purpose of the investigation. Instead of: “This study investigated whether kusho could help older adults solve a cognitive task” it should be:

“This study investigates whether the facilitative effect of kusho is affected by old age”.

2. Supporting information: I understand that due to the missing data on vocabulary the authors are not able to address the role played by this variable and therefore they provided few existing results as supplementary material. Though, they have to explain the sense of these data. In other words, whether higher scores reflect higher lexical skills.

3. Discussion p. 12:

a. The first sentence on the 2nd paragraph needs to be rephrased (lines 324 to 326). The meaning is not clear to me.

b. Lines 334 and 335: It should be “global cognitive status” and not “general cognitive decline”.

c. Line 335: The authors claim that a possible candidate mediating the effects of education is visual

processing. However, it is largely known that older adults suffer normal declines not only on their visual acuity, but also on their perceptual visual abilities (see e.g., Monge & Madden, 2016). Importantly, no visual evaluation was conducted in this study. Thus, I would rather suggest thinking about the advantages of well-learned proprioceptive functions in this population. Some authors have suggested that no age effect exists in proprioception when older adults know in advance the movements related to a specific action (Stelmach & Sirica, 1986).

Monge, Z. A. & Madden, D. J. (2016). Linking cognitive and visual perceptual decline in healthy aging: The information degradation hypothesis. Neuroscience and Biobehavioral Reviews, 69, 166-173.

Stelmach, G. E. & Sirica, A. (1986). Aging and Proprioception. Age, 9, 99-103.

Reviewer #3: Major points.

I recognized that the authors improved the manuscript greatly. However, I still have an uncomfortable feeling against their logics. I will indicate two points; their aim of the study and their way of description.

Their aim of the study:

First, I would categorize two types of papers.

(1) Papers that reveal a new phenomenon.

(2) Papers that investigate a mechanism of a phenomenon.

This paper seems to belong to the first one, with having a factor of the second. It revealed that the elderly people in Japan showed kusho behaviors in a similar way as having shown in younger generations, and as well investigated the relationship with individual parameters including years of education.

If my understanding above is correct, then I suppose their main aim of the study was to reveal the incidence of kusho behaviors among elderly people in Japan. The authors might originally have no interests in the mechanism of that. However, they happened to find a significant difference in years of education, which was included in questionnaire entries to obtain the basic information of subjects. By this observation, they found themselves to be obliged to discuss that in the paper.

Am I right?

If it was the case, I would like authors to more clearly indicate these backgrounds. Otherwise, I feel a difficulty to get their points in the current version of the manuscript.

Also, I would like authors to more explicitly explain why they considered it was important to reveal the incidence of kusho among the elderly in Japan. I suppose this was the main claim that authors should have appealed.

Actually, I think it might be better if they had an interest in the investigation of the mechanism of kusho from the beginning. They might want to measure “sensorimotor system” (line 47) possibly using RT of a button press to a visual cue and “cognitive functions” (lines 47-48) using assessments. They tried to use 100 RAKAN (line 95) for the latter, but unfortunately, it was not completed to all participants.

Here, for the next chance of the continuation of this study, another idea would be Japanese Adult Reading Test (JART), which was standardized and relatively easy to conduct.

Their way of description:

Another reason that I feel a difficulty in grasping their points is their way of writing the manuscript. I will raise two points: paragraph writing (again) and reduction of sentences beginning with a particle.

(1) Paragraph writing

As I wrote in the previous review, the authors frequently put their conclusion (main statement) at the last part of the paragraph. This is a feature that is frequently observed among people from Asia. I would suggest that they can move the last sentence to the top of the paragraph.

Example #1: page 3, the paragraph beginning with “To investigate…” (line 49)

They may want to start the paragraph with the last sentence of this paragraph, i.e., “In the present study…” (lines 58 - 61). They may want to modify it such as:

We hypothesized that the elderly people would show a better cognitive performance in a kusho condition than in the other conditions because… something like this.

Example #2: page 10, the paragraph beginning with “While previous studies…” (line 266)

They may want to start with the last sentence of this paragraph, i.e., “The present results suggest that the interaction between…” (Lines 277 – 279).

Then, they could deepen and strengthen the discussion.

Example #3: page 12, the paragraph beginning with “Although this study did not clarify…” (line 324)

They may want to start with the last sentence of this paragraph, i.e., “Our data suggest that decline in a specific function may be involved with a modulation of the kūsho effect in the kanji construction task” (lines 343-344).

(2) Reduction of sentences beginning with a particle

There are too many sentences beginning with a particle (e.g., For…, In the…) . Please reduce them by half.

By the way, did authors ask a copy-editing company? If not, they should ask.

Minor points.

(1) Please remove discussion from Materials and Methods.

(2) Line 153. What did they mean by “only one visual condition”? My understanding is that authors had 3 conditions, as shown in Figure 2. In lines 349-350, they also wrote; “this study used only one visual condition instead of comparing the two visual conditions.” Please clarify what was “one” or “two”.

(3) Authors frequently use the word “hand condition”. Could it be just “experimental condition,” because there were no “foot” conditions?

(4) I found a discrepancy in the description of RT.

At line 121, they wrote; “Response times were not statistically analyzed or discussed because participants’ voices were not always loud or clear enough to detect the onset of the responses, and the ratio of missing values was very high (31% of correct responses were missing values).”

However, they reported RT in line 209; “The average response times were 6.9 s (SD = 1.2) in the kūsho condition, 6.5 s (SD = 1.8) in the static condition, and 6.8 s (SD = 1.3) in the circle-drawing condition.”

Did they mean that the report was for the remaining 69% (i.e., 100 – 31) of responses?

Also, how did they measure RT?

Please clarify.

**********

7. PLOS authors have the option to publish the peer review history of their article (what does this mean?). If published, this will include your full peer review and any attached files.

If you choose “no”, your identity will remain anonymous but your review may still be made public.

Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy.

Reviewer #1: No

Reviewer #2: Yes: Claudia Rodríguez-Aranda

Reviewer #3: No

PLoS One. 2019 Dec 27;14(12):e0226832. doi: 10.1371/journal.pone.0226832.r004

Author response to Decision Letter 1

2 Oct 2019

Dear Editor and Reviewers,

We greatly appreciate your rigorous and fair review of the manuscript as well as your insightful comments. The revised manuscript has been modified in response to the comments, as follows:

All comments from the reviewers have been responded to in the following pages. In the revised manuscript, revisions are highlighted using violet font (red is for the first revision).

We look forward to hearing from you regarding our submission. We would be glad to respond to any further questions and comments that you may have.

Sincerely,

Yoshihiro Itaguchi

Attachment

Submitted filename: Responses_to_reviewers1003.docx

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PLoS One. doi: 10.1371/journal.pone.0226832.r005

Decision Letter 2

Emmanuel Manalo

27 Nov 2019

PONE-D-19-16768R2

Writing in the air: facilitative effects of finger writing in older adults

PLOS ONE

Dear Dr. Itaguchi,

Thank you for submitting your manuscript to PLOS ONE. After careful consideration, we feel that it has merit but does not fully meet PLOS ONE’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that systematically addresses all the points raised during the review process. Please see my comments below, and pay particular attention to the additional revisions indicated by Reviewers 1 and 3.

We would appreciate receiving your revised manuscript by Jan 11 2020 11:59PM. When you are ready to submit your revision, log on to https://www.editorialmanager.com/pone/ and select the 'Submissions Needing Revision' folder to locate your manuscript file.

If you would like to make changes to your financial disclosure, please include your updated statement in your cover letter.

Please include the following items when submitting your revised manuscript:

A rebuttal letter that responds to each point raised by the academic editor and reviewer(s). This letter should be uploaded as separate file and labeled 'Response to Reviewers'.
A marked-up copy of your manuscript that highlights changes made to the original version. This file should be uploaded as separate file and labeled 'Revised Manuscript with Track Changes'.
An unmarked version of your revised paper without tracked changes. This file should be uploaded as separate file and labeled 'Manuscript'.

We look forward to receiving your revised manuscript.

Kind regards,

Emmanuel Manalo, PhD

Academic Editor

PLOS ONE

Additional Editor Comments (if provided):

This second revision is much improved, and the reviewers' comments reflect that improvement in the quality of the manuscript.

However, please note that both Reviewers 1 and 3 have indicated further (more minor) revisions that need to be made, so can you please carefully and systematically address all of those? Note that Reviewer 1 included an annotated version of your manuscript showing some of the revisions that need to be made.

If you can please provide your responses on a point-by-point basis, it would make it easier for me to make the next decision on your manuscript. Depending on the extent to which you have clearly implemented the modifications indicated by the reviewers, it may not be necessary for me to send your next revision to them for further review.

[Note: HTML markup is below. Please do not edit.]

Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

Reviewer #1: All comments have been addressed

Reviewer #2: All comments have been addressed

Reviewer #3: (No Response)

**********

2. Is the manuscript technically sound, and do the data support the conclusions?

Reviewer #1: Partly

Reviewer #2: Yes

Reviewer #3: Yes

**********

3. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: I Don't Know

Reviewer #2: Yes

Reviewer #3: Yes

**********

4. Have the authors made all data underlying the findings in their manuscript fully available?

Reviewer #1: Yes

Reviewer #2: Yes

Reviewer #3: Yes

**********

5. Is the manuscript presented in an intelligible fashion and written in standard English?

Reviewer #1: No

Reviewer #2: Yes

Reviewer #3: Yes

**********

6. Review Comments to the Author

Reviewer #1: I feel that the ms. is improved, and although the research behind it still not ideally designed, it is publishable. In my attached text I make several suggestions for improving the diction and clarity of the ms., and I would strongly suggest that the authors consider these several small points.

Reviewer #2: The manuscript has been greatly improved and the authors have addressed all my comments.

I have no additional concerns or suggestions.

Reviewer #3: I found that the manuscript has been greatly improved. In the previous versions of the manuscript, their description and discussion were quite superficial. Specifically, it previously failed to sufficiently discuss the underlying cognitive processes of kusho behaviors, which did not qualify the appearance in the journal; they just appeared to conduct the experiment by bothering elderly people and displayed the results without a sufficient discussion. I think their biggest fault would be their lack of a specific hypothesis regarding the “facilitative effect” of kusho; in short, facilitate what? Why can the kusho improve the ratio of correct answers in the kanji construction puzzle? According to their Introduction, they appear to have no ideas for that. (I would say, it appears they cannot understand what reviewers really suggested in this point.)

However, their discussion has been sufficiently deepened and well described after these review processes. Actually, I would say they are still a little superficial and have not fully discussed some important points that this topic (kusho) has raised in the research field so far, specifically, the underlying cognitive procedures including aspects in the visual feedback. Nonetheless, considering the limitation of the publication, I think they adequately mentioned the points related to the kusho observed in the elderly people in the latest version.

I hope the authors continue to investigate the mechanism of the kusho behaviors to conduct experiments that focus on “specific cognitive functions” that they argued in Discussion.

I would note a minor point.

Page 5, lines 116-118.

In Fig 1a, for example, to make the original kanji character, all subparts were vertically compressed while the top subpart was placed such that it overlapped with the other parts.

The example in the Fig. 1a does not appear to fit to the explanation; the explanation also does not match to the caption of Fig. 1.

**********

7. PLOS authors have the option to publish the peer review history of their article (what does this mean?). If published, this will include your full peer review and any attached files.

If you choose “no”, your identity will remain anonymous but your review may still be made public.

Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy.

Reviewer #1: No

Reviewer #2: Yes: Claudia Rodríguez-Aranda

Reviewer #3: No

Attachment

Submitted filename: PONE-D-19-16768 R2 Comments.docx

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PLoS One. 2019 Dec 27;14(12):e0226832. doi: 10.1371/journal.pone.0226832.r006

Author response to Decision Letter 2

2 Dec 2019

All responses are included in the attached file.

Attachment

Submitted filename: Kusho_older_adults_20191203_Responses.docx

Click here for additional data file.^{(22.8KB, docx)}

PLoS One. doi: 10.1371/journal.pone.0226832.r007

Decision Letter 3

Emmanuel Manalo

9 Dec 2019

Writing in the air: facilitative effects of finger writing in older adults

PONE-D-19-16768R3

Dear Dr. Itaguchi,

We are pleased to inform you that your manuscript has been judged scientifically suitable for publication and will be formally accepted for publication once it complies with all outstanding technical requirements.

Within one week, you will receive an e-mail containing information on the amendments required prior to publication. When all required modifications have been addressed, you will receive a formal acceptance letter and your manuscript will proceed to our production department and be scheduled for publication.

Shortly after the formal acceptance letter is sent, an invoice for payment will follow. To ensure an efficient production and billing process, please log into Editorial Manager at https://www.editorialmanager.com/pone/, click the "Update My Information" link at the top of the page, and update your user information. If you have any billing related questions, please contact our Author Billing department directly at authorbilling@plos.org.

If your institution or institutions have a press office, please notify them about your upcoming paper to enable them to help maximize its impact. If they will be preparing press materials for this manuscript, you must inform our press team as soon as possible and no later than 48 hours after receiving the formal acceptance. Your manuscript will remain under strict press embargo until 2 pm Eastern Time on the date of publication. For more information, please contact onepress@plos.org.

With kind regards,

Emmanuel Manalo, PhD

Academic Editor

PLOS ONE

Additional Editor Comments (optional):

Reviewers' comments:

PLoS One. doi: 10.1371/journal.pone.0226832.r008

Acceptance letter

Emmanuel Manalo

11 Dec 2019

PONE-D-19-16768R3

Writing in the air: facilitative effects of finger writing in older adults

Dear Dr. Itaguchi:

I am pleased to inform you that your manuscript has been deemed suitable for publication in PLOS ONE. Congratulations! Your manuscript is now with our production department.

If your institution or institutions have a press office, please notify them about your upcoming paper at this point, to enable them to help maximize its impact. If they will be preparing press materials for this manuscript, please inform our press team within the next 48 hours. Your manuscript will remain under strict press embargo until 2 pm Eastern Time on the date of publication. For more information please contact onepress@plos.org.

For any other questions or concerns, please email plosone@plos.org.

Thank you for submitting your work to PLOS ONE.

With kind regards,

PLOS ONE Editorial Office Staff

on behalf of

Professor Emmanuel Manalo

Academic Editor

PLOS ONE

Associated Data

This section collects any data citations, data availability statements, or supplementary materials included in this article.

Supplementary Materials

S1 Table. Raw data obtained in the experiment.

(XLSX)

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Attachment

Submitted filename: Kusho_older_adults_Responses_to_Reviewers_20190819.docx

Click here for additional data file.^{(77.1KB, docx)}

Attachment

Submitted filename: Responses_to_reviewers1003.docx

Click here for additional data file.^{(37.8KB, docx)}

Attachment

Submitted filename: PONE-D-19-16768 R2 Comments.docx

Click here for additional data file.^{(15.5KB, docx)}

Attachment

Submitted filename: Kusho_older_adults_20191203_Responses.docx

Click here for additional data file.^{(22.8KB, docx)}

Data Availability Statement

All relevant data are within the manuscript and its Supporting Information files.

[pone.0226832.ref001] 1.Lichtenberger EO, Kaufman AS. Essentials of WAIS-IV assessment: John Wiley & Sons; 2009. [Google Scholar]

[pone.0226832.ref002] 2.Mayr U. Age differences in the selection of mental sets: the role of inhibition, stimulus ambiguity, and response-set overlap. Psychol Aging. 2001;16(1):96 10.1037/0882-7974.16.1.96 [DOI] [PubMed] [Google Scholar]

[pone.0226832.ref003] 3.Bugg JM, DeLosh EL, Davalos DB, Davis HP. Age differences in Stroop interference: Contributions of general slowing and task-specific deficits. Aging, Neuropsychology, and Cognition. 2007;14(2):155–67. [DOI] [PubMed] [Google Scholar]

[pone.0226832.ref004] 4.Verhaegen C, Poncelet M. Changes in naming and semantic abilities with aging from 50 to 90 years. J Int Neuropsychol Soc. 2013;19(2):119–26. 10.1017/S1355617712001178 [DOI] [PubMed] [Google Scholar]

[pone.0226832.ref005] 5.Lindenberger U, Baltes PB. Intellectual functioning in old and very old age: cross-sectional results from the Berlin Aging Study. Psychol Aging. 1997;12(3):410 10.1037//0882-7974.12.3.410 [DOI] [PubMed] [Google Scholar]

[pone.0226832.ref006] 6.Sasaki M. Why do Japanese write characters in space? International Journal of Behavioral Development. 1987;10(2):135–49. [Google Scholar]

[pone.0226832.ref007] 7.Kess JF, Miyamoto T. Japanese psycholinguistics: A classified and annotated research bibliography: John Benjamins Publishing; 1994. [Google Scholar]

[pone.0226832.ref008] 8.Endo Y. The role of a motoric aspect of representation: Spontaneous writing-like behavior in Japanese. Practical aspects of memory: Current research and issues. 1988;2:459–63. [Google Scholar]

[pone.0226832.ref009] 9.Itaguchi Y, Yamada C, Fukuzawa K. Writing in the air: Contributions of finger movement to cognitive processing. PLoS One. 2015;10(6):e0128419 10.1371/journal.pone.0128419 [DOI] [PMC free article] [PubMed] [Google Scholar]

[pone.0226832.ref010] 10.Itaguchi Y, Yamada C, Yoshihara M, Fukuzawa K. Writing in the air: A visualization tool for written languages. PLoS One. 2017;12(6):e0178735 10.1371/journal.pone.0178735 [DOI] [PMC free article] [PubMed] [Google Scholar]

[pone.0226832.ref011] 11.Thomas M. "Air writing" and second language learners’ knowledge of Japanese kanji. Japanese Language and Literature. 2013:23–58. [Google Scholar]

[pone.0226832.ref012] 12.Thomas M. Air writing as a technique for the acquisition of Sino‐Japanese characters by second language learners. Language Learning. 2015;65(3):631–59. [Google Scholar]

[pone.0226832.ref013] 13.Kess JF, Miyamoto T. Kanji knowledge as read-only vs. write-only: The effect of the computer age. Japan in the Global Age. 2001:175–87. [Google Scholar]

[pone.0226832.ref014] 14.Yim-Ng RV, Andrade Jackie, Yuet-Yee. Contribution of finger tracing to the recognition of Chinese characters. Int J Lang Commun Disord. 2000;35(4):561–71. 10.1080/136828200750001296 [DOI] [PubMed] [Google Scholar]

[pone.0226832.ref015] 15.Hoosain R. Psycholinguistic implications for linguistic relativity: A case study of Chinese: Psychology Press; 1991. [Google Scholar]

[pone.0226832.ref016] 16.Springer MV, McIntosh AR, Winocur G, Grady CL. The relation between brain activity during memory tasks and years of education in young and older adults. Neuropsychology. 2005;19(2):181 10.1037/0894-4105.19.2.181 [DOI] [PubMed] [Google Scholar]

[pone.0226832.ref017] 17.Wilson R, Hebert L, Scherr P, Barnes L, De Leon CM, Evans D. Educational attainment and cognitive decline in old age. Neurology. 2009;72(5):460–5. 10.1212/01.wnl.0000341782.71418.6c [DOI] [PMC free article] [PubMed] [Google Scholar]

[pone.0226832.ref018] 18.Colsher PL, Wallace RB. Longitudinal application of cognitive function measures in a defined population of community-dwelling elders. Ann Epidemiol. 1991;1(3):215–30. 10.1016/1047-2797(91)90001-s [DOI] [PubMed] [Google Scholar]

[pone.0226832.ref019] 19.Stern Y, Albert S, Tang M-X, Tsai W-Y. Rate of memory decline in AD is related to education and occupation Cognitive reserve? Neurology. 1999;53(9):1942-. 10.1212/wnl.53.9.1942 [DOI] [PubMed] [Google Scholar]

[pone.0226832.ref020] 20.Au R, Joung P, Nicholas M, Obler LK, Kass R, Albert ML. Naming ability across the adult life span. Aging, Neuropsychology, and Cognition. 1995;2(4):300–11. [Google Scholar]

[pone.0226832.ref021] 21.Amano S, Kondo T, editors. Estimation of mental lexicon size with word familiarity database. ICSLP; 1998.

[pone.0226832.ref022] 22.Maher LM, Clayton MC, Barrett AM, Schober-Peterson D, Rothi LJG. Rehabilitation of a case of pure alexia: Exploiting residual abilities. J Int Neuropsychol Soc. 1998;4(06):636–47. [DOI] [PubMed] [Google Scholar]

[pone.0226832.ref023] 23.Dejerine J. Sur un cas de cécité verbale avec agraphie suivi d’autopsie. Mémoires de la Société de Biologie. 1891;3:197–201. [Google Scholar]

[pone.0226832.ref024] 24.Goldstein K. Language and language disturbances; aphasic symptom complexes and their significance for medicine and theory of language. 1948.

[pone.0226832.ref025] 25.Kashiwagi T, Kashiwagi A. Recovery process of a Japanese alexic without agraphia. Aphasiology. 1989;3(1):75–91. [Google Scholar]

[pone.0226832.ref026] 26.Tanaka S, Katayama M, Ozawa T, Inui T. A case of pure alexia who can read letters by observing others’ writing action. Japanese Journal of Neuropsychology. 2002;18:68–75. [Google Scholar]

[pone.0226832.ref027] 27.Bartolomeo P, Bachoud-Lévi A-C, Chokron S, Degos D. Visually-and motor-based knowledge of letters: evidence from a pure alexic patient. Neuropsychologia. 2002;40(8):1363–71. 10.1016/s0028-3932(01)00209-3 [DOI] [PubMed] [Google Scholar]

[pone.0226832.ref028] 28.Longcamp M, Anton J-L, Roth M, Velay J-L. Visual presentation of single letters activates a premotor area involved in writing. Neuroimage. 2003;19(4):1492–500. 10.1016/s1053-8119(03)00088-0 [DOI] [PubMed] [Google Scholar]

[pone.0226832.ref029] 29.Longcamp M, Zerbato-Poudou M-T, Velay J-L. The influence of writing practice on letter recognition in preschool children: A comparison between handwriting and typing. Acta Psychol (Amst). 2005;119(1):67–79. [DOI] [PubMed] [Google Scholar]

[pone.0226832.ref030] 30.Insel K, Morrow D, Brewer B, Figueredo A. Executive function, working memory, and medication adherence among older adults. The Journals of Gerontology Series B: Psychological Sciences and Social Sciences. 2006;61(2):P102–P7. 10.1093/geronb/61.2.p102 [DOI] [PubMed] [Google Scholar]

[pone.0226832.ref031] 31.Cohen RG, Sternad D. State space analysis of timing: exploiting task redundancy to reduce sensitivity to timing. J Neurophysiol. 2012;107(2):618–27. 10.1152/jn.00568.2011 [DOI] [PMC free article] [PubMed] [Google Scholar]

[pone.0226832.ref032] 32.Berryhill ME, Jones KT. tDCS selectively improves working memory in older adults with more education. Neurosci Lett. 2012;521(2):148–51. 10.1016/j.neulet.2012.05.074 [DOI] [PubMed] [Google Scholar]

[pone.0226832.ref033] 33.Stern Y, Gurland B, Tatemichi TK, Tang MX, Wilder D, Mayeux R. Influence of education and occupation on the incidence of Alzheimer’s disease. JAMA. 1994;271(13):1004–10. [PubMed] [Google Scholar]

[pone.0226832.ref034] 34.Piccinin AM, Muniz-Terrera G, Clouston S, Reynolds CA, Thorvaldsson V, Deary IJ, et al. Coordinated analysis of age, sex, and education effects on change in MMSE scores. Journals of Gerontology Series B: Psychological Sciences and Social Sciences. 2012;68(3):374–90. [DOI] [PMC free article] [PubMed] [Google Scholar]

[pone.0226832.ref035] 35.Soldan A, Pettigrew C, Albert M. Evaluating cognitive reserve through the prism of preclinical Alzheimer disease. Psychiatric Clinics. 2018;41(1):65–77. 10.1016/j.psc.2017.10.006 [DOI] [PMC free article] [PubMed] [Google Scholar]

[pone.0226832.ref036] 36.Matsuo K, Kato C, Tanaka S, Sugio T, Matsuzawa M, Inui T, et al. Visual language and handwriting movement: functional magnetic resonance imaging at 3 tesla during generation of ideographic characters. Brain Res Bull. 2001;55(4):549–54. 10.1016/s0361-9230(01)00564-0 [DOI] [PubMed] [Google Scholar]

[pone.0226832.ref037] 37.Verhaeghen P. Aging and vocabulary score: A meta-analysis. Psychol Aging. 2003;18(2):332 10.1037/0882-7974.18.2.332 [DOI] [PubMed] [Google Scholar]

[pone.0226832.ref038] 38.Uttl B. North American Adult Reading Test: age norms, reliability, and validity. J Clin Exp Neuropsychol. 2002;24(8):1123–37. 10.1076/jcen.24.8.1123.8375 [DOI] [PubMed] [Google Scholar]

[pone.0226832.ref039] 39.Kempler D, Teng EL, Dick M, Taussig IM, Davis DS. The effects of age, education, and ethnicity on verbal fluency. J Int Neuropsychol Soc. 1998;4(6):531–8. 10.1017/s1355617798466013 [DOI] [PubMed] [Google Scholar]

[pone.0226832.ref040] 40.Michaux N, Masson N, Pesenti M, Andres M. Selective interference of finger movements on basic addition and subtraction problem solving. Exp Psychol. 2013;60(3):197–205. 10.1027/1618-3169/a000188 [DOI] [PubMed] [Google Scholar]

[pone.0226832.ref041] 41.Bender A, Beller S. Nature and culture of finger counting: Diversity and representational effects of an embodied cognitive tool. Cognition. 2012;124(2):156–82. 10.1016/j.cognition.2012.05.005 [DOI] [PubMed] [Google Scholar]

PERMALINK

Writing in the air: Facilitative effects of finger writing in older adults

Yoshihiro Itaguchi

Chiharu Yamada

Kazuyoshi Fukuzawa

Roles

Abstract

Introduction

Materials and methods

Participants

Table 1. Demographic data of participants.

Kanji construction task

Fig 1. Experimental stimuli and sequence.

Stimulus

Analysis

Ethics statement

Results

Facilitative effect of kūsho behavior

Fig 2. The number of correct responses in the kanji construction task.

Correlation analyses of the kūsho effect

Table 2. Correlation matrix for the number of correct responses in the three experimental conditions and personal factors.

Fig 3.

Table 3. Partial correlation matrix of the kūsho effect and the other three factors (n = 25).

Discussion

Facilitative kūsho effects in older adults

Education years, MMSE score, and other possible variables for the kūsho effect

Supporting information

Data Availability

Funding Statement

References

Decision Letter 0

Emmanuel Manalo

Roles

Author response to Decision Letter 0

Decision Letter 1

Emmanuel Manalo

Roles

Author response to Decision Letter 1

Decision Letter 2

Emmanuel Manalo

Roles

Author response to Decision Letter 2

Decision Letter 3

Emmanuel Manalo

Roles

Acceptance letter

Emmanuel Manalo

Roles

Associated Data

Supplementary Materials

Data Availability Statement

ACTIONS

PERMALINK

RESOURCES

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