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Published in final edited form as: Dev Sci. 2015 Jul 31;19(6):892–900. doi: 10.1111/desc.12335

Delayed Match Retrieval: A Novel Anticipation-Based Visual Working Memory Paradigm

Zsuzsa Kaldy 1, Sylvia Guillory 1, Erik Blaser 1
PMCID: PMC4733613  NIHMSID: NIHMS738359  PMID: 26234951

Abstract

We tested 8- and 10-month-old infants’ Visual Working Memory (VWM) for object-location bindings — what is where — with a novel paradigm, Delayed Match Retrieval, that measured infants’ anticipatory gaze responses (using a Tobii T120 eye tracker). In an inversion of Delayed-Match-to-Sample tasks and with inspiration from the game Memory, in test trials, three face-down virtual ‘cards’ were presented. Two flipped over sequentially (revealing, e.g., a swirl pattern and then a star), and then flipped back face-down. Next, the third card was flipped to reveal a match (e.g. a star) to one of the previously seen, now-face-down cards. If infants looked to the location where the (now face-down) matching card had been shown, this was coded as a correct response. To encourage anticipatory looks, infants subsequently received a reward (a brief, engaging animation) presented at that location. 10-month-old infants performed significantly above chance, showing that their VWM could hold object-location information for the two cards. Overall, 8-month-olds’ performance was at chance, but they showed a robust learning trend. These results corroborate previous findings (Kaldy & Leslie, 2005; Oakes, Ross-Sheehy, & Luck, 2006) and point to rapid development of VWM for object-location bindings. However, compared to previous paradigms that measure passive gaze responses to novelty, this paradigm presents a more challenging, ecologically relevant test of VWM, as it measures the ability to make online predictions and actively localize objects based on VWM. As well, this paradigm can be readily scaled-up to test toddlers or older children without significant modification.

Keywords: visual working memory, infant, object-location binding, anticipation, eye movements, Delayed Match Retrieval

Developmental psychologists have studied infants’ memory for over fifty years, often focussing on visual stimuli, such as faces or geometric patterns (e.g. Fagan, 1977; Rose, 1981; Rose, Feldman, & Jankowski, 2001); showing, for example, that even a few-hour-old infant can remember a visual stimulus (Fantz, 1964; Slater, Earle, Morison, & Rose, 1985). But beyond recognition of an object, or noting the relevance of a particular location, what is the developmental course of the integration of this information? After all, it is reasonable to think that the functional units of visual cognition are objects situated in space (Hollingworth & Rasmussen, 2010; Kahneman, Treisman & Gibbs, 1992; Leslie, Xu, Tremoulet & Scholl, 1998). Studies using classic methods, such as the Delayed Response task, with eye-gaze based measures, have shown that 5-month-old infants locate a hidden object from multiple hiding locations over a 3-second delay (Hofstadter & Reznick, 1996; Reznick, Morrow, Goldman, & Snyder, 2004). This ability gradually develops over the second half of the first year (Pelphrey et al., 2004) This has also been demonstrated using violation-of-expectation paradigms with 5- and 6-month-olds (Newcombe, Huttenlocher, & Learmonth, 1999; Kaldy & Leslie, 2005) with even longer delays (7–10 s). On the other hand, there is ample evidence showing that infants at 4–6 months of age have trouble retaining featural/identity information about objects when more than one object is involved (Kaldy & Leslie, 2005; Kibbe & Leslie, 2011; Kwon, Luck & Oakes, 2013; Mareschal & Johnson, 2003; Simon, Hespos & Rochat, 1995). In a task that required remembering two object identity/location bindings, 9-month-olds (but not 6-month-olds) were able to succeed with a 7-second delay (Kaldy & Leslie, 2005). When the retention interval is minimized to 300 ms, there is evidence that infants as young as 7.5 months can remember object-location bindings for multiple objects (Oakes, Ross-Sheehy & Luck, 2006).

Addressing limitations of VWM studies based on the novelty preference

In all of the above studies (except for the delayed-response task), the participant is a passive observer of a sequence of stimuli and events and the assumption is that he or she will spontaneously compare the contents of a memory representation with the currently perceived stimuli (for reviews, see Kavšek, 2013; Rose, Feldman & Jankowski, 2004). This same logic underlies the Violation-of-Expectation paradigms used to examine higher-level object cognition abilities (Baillargeon, Spelke, & Wasserman, 1985) and classic studies using novelty preference procedures in which infants are shown a stimulus, and then their memory for that stimulus is inferred from their looking preference for a novel one (e.g. Visual Paired Comparison: Fagan, 1970; habituation/dishabituation: Pancratz & Cohen, 1970). Thus far, work on VWM for object-location bindings in infants has used the same general approach (Kaldy & Leslie, 2003, 2005; Mareschal & Johnson, 2003; Newcombe et al., 1999; Ross-Sheehy, Oakes & Luck, 2003). These VWM paradigms based on novelty preferences have moved our understanding forward, but have three limitations that our new paradigm seeks to address.

For one, the novelty preference requires both detection of a change, and interest in that change. When an infant fails to react when, say, a red star goes behind an occluder and a pink star subsequently emerges, we do not know if the infant failed to detect the change or was just not surprised by the change; the change may be noted but not notable. In our paradigm, we employ infant-tailored ‘rewards’ (e.g. engaging visual animations) for correct responses, similarly to Delayed-Match-to-Sample paradigms (since Weinstein, 1941). A compelling reward offers an incentive to remember and respond that is independent of inherent interest in task stimuli or events (a logic underlying training paradigms: e.g. Siqueland & Lipsitt, 1966; Rovee-Collier & Gekoski, 1979). (It is worth noting here too that the ‘mode’ of rewards is crucial. For instance, early results showed that infants failing at Delayed Non-matching to Sample (DNMS) until 21 months of age (Diamond, 1990; Overman, 1990). However, Diamond and her colleagues later showed that infants could succeed much earlier (at 9 months), if their response and the reward were clearly connected (e.g. immediate verbal praise or a reward physically attached to the sought-after novel object (Diamond, Churchland, Cruess, & Kirkham, 1999)).

Secondly, the novelty preference can be ambiguous. When an infant does look longer when, say, a green star emerges where a red one had been, does the infant think that the the red star has undergone an unnaturally large change in appearance, or that a new object has usurped its location? Our paradigm sidesteps this issue altogether and asks a different question, simply, “Please show us where you saw this object before.” This example also illustrates what we think is the third contribution of our paradigm. The novelty preference is passive; a reaction to a change in an object-location binding. There is much more to object cognition in dynamic real world settings than the expression of surprise. Many situations require the infant to recall and act upon what is where information. Our paradigm is specifically tailored to test the development of this ability.

Delayed Match Retrieval (DMR) requires the online application of object-location bindings

Eye-trackers have made the measurement of anticipatory gaze responses possible and enabled a “shift from studies of the macrostructure of looking behavior to the microstructure of patterns of fixation” (Aslin, 2012, p.127). Predictive gaze responses have been used fruitfully in studies of infants’ social cognition (e.g. Falck-Ytter, Gredebäck, & von Hofsten, 2006; Southgate, Senju, & Csibra, 2007) and other domains, such as object tracking (Johnson, Amso, & Slemmer, 2003), cognitive flexibility (Kovács & Mehler, 2009a, 2009b; Albareda-Castellot, Pons & Sebastian-Galles, 2011) and categorization (McMurray, & Aslin, 2004). The dependent variables are usually based on ‘first looks’ (both location and latency) and fixation durations. For instance, Addyman and Marechal (2010) tested 4- and 8-month-old infants’ ability to learn the categories ‘same’ and ‘different’ in an anticipatory looking task. Infants were trained to search in one location if they categorized a pair of objects as ‘same’ and in another location if they categorized them as ‘different’. The authors measured infants’ binary preference based on first looks and proportion of looking time to the two alternatives. Both of these two measures showed rapid learning in the older group, but only the proportion of looking time did in the younger group. In the current study, we used both measures.

Our novel Delayed Match Retrieval (DMR) paradigm inverts the classic Delayed-Match-to-Sample task. In the classic task, a sample object is presented (say, a star) and removed, a delay period ensues, and then two objects are presented: a match (another star) and a non-match (say, a triangle). An adult would be asked, or an animal trained with rewards, to pick out the match. Importantly, DMR inverts this: potential matches/non-matches are presented first, then obscured. Only after that (and a delay), is the sample revealed; the participant then seeks out the (now hidden) match. This inversion means that high performance is achieved only when all object-location bindings are successfully maintained in VWM during the delay. Participants are encouraged to do this through visual rewards (i.e. “Here is a red star on the left and a green star on the right. Hold this what is where information in memory while they are hidden. Now, here is another red star. If you look back to where you saw the first one, you’ll see a fun reward there!”). Building on Addyman and Mareschal’s findings with 4- and 8-month-olds, we expected the 8–10-month-old infants in our task to be able to rapidly learn this rule. Our paradigm included training trials where 1) infants could familiarize themselves to the cards and images, 2) looking behavior could be recorded as the cards were flipping and moving, and 3) infants were shown that transitory, engaging animations occurred at the Match location (test trials also had this reward structure to serve as rule training).

Method

Participants

Two groups of healthy, full-term infants participated. There were fourteen infants in the 8-month-old age group (Mage = 243.1 days, SD = 13.2, range: 224–261 days, 6 females) and twelve in the 10-month-old group (Mage = 297.2 days, SD = 17.3, range: 270–328 days, 4 females). Eleven additional infants were tested, but excluded (four due to fussiness, one due to inability to calibrate, three due to eye-tracker errors and three due to experimenter errors). Families were contacted using birth records, resided primarily in the Greater Boston area, and received a small gift for participation. None of our infant participants had first-degree relatives with colorblindness.

Stimuli

Stimuli were self-occluding, virtual ‘cards’ that could be presented face-up, revealing to-be-remembered objects, or, uninformatively, face-down. This design is quasi-naturalistic (no sudden onset/offset of objects), and it has the advantage of not requiring additional objects to serve as occluders. One of four possible objects — star, swirl, face, or tree — could appear on a card (Figure 1a). Cards subtended 4×6 deg and were arranged symmetrically (top, left bottom, right bottom) with their centers 5 deg from the center of the screen.

Figure 1. a) Experimental stimuli.

Figure 1

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Face-up, virtual ‘cards’ used in the roles of Sample/ Match, and non-Match could contain one of four objects. b) Areas of Interest (AOI’s) for eye-tracking analyses were drawn around the Match and non-Match cards (shown face- down).

Apparatus and procedure

We used a Tobii T120 eye-tracker (Tobii Technology, Stockholm, Sweden) and Tobii Studio 2.1.8 software to measure eye movements. Participants sat on their caregivers’ lap, approximately 60 cm away from the eye-tracker’s display in a dimly lit, isolated testing area. Caregivers wore occluding glasses and were asked not to interact with their infants during testing. Before each block of trials, infants performed the default Tobii 5-point infant gaze calibration.

In training trials, there was no VWM task. Instead, infants were familiarized to the three-card configuration, objects, behaviors, sound effects, and the rule of ‘matching’ (Figure 2). First, infants saw three face-down cards fly in. After 1.5 s, the Sample card was revealed. After 2.5 s, the Match was revealed, accompanied by one of three brief, rewarding animations (e.g. the Match card jiggled and threw off pink sparks). The Match then moved next to the Sample and tilted toward it to make contact (imitating a “kiss”, accompanied by a kissing sound). The third card never flipped face up. At the end of the trial, all cards flew off the screen. There were four such training trials, one for each of the four objects.

Figure 2. Training trial.

Figure 2

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The first four trials of every block were training trials, designed to familiarize participants with task stimuli and events, and also to alert participants to a critical component of DMR: a brief, rewarding animation occurred at the location of the Match. Since the animation follows the brief exposure of the Match card, the relationship between ‘matching’ and reward is made explicit.

Test trials began when three face down cards flew into view (Figure 3, please see also Supplementary Movie 1). Following this, the potential Match card and the potential non-Match card were exposed (the order of exposure was counterbalanced). The first card was exposed for 2.5 s and remained face-up while the second card was exposed for 2.5 s. Both cards were then flipped face-down, starting a 1.5-second retention interval during which the participants had to maintain object-location information in VWM (i.e. the binding of location and identity of the cards). Then the third card, the Sample, flipped over, revealing a match to one of the previously seen, now face-down cards. This began the 4 s response interval, during which eye movements were monitored (see Data Analysis)1. The response interval ended with a reward animation at the Match card’s location that occurred simultaneously with its appearance. This reward was so brief (167 ms) that infants needed to have made an anticipatory eye movement to the (face-down) Match card’s location in order to fixate it; an implicit instruction (‘look for the match to catch the reward animation!’). Following this, the matching cards (Sample and Match) remained face-up and the Match card moved in to ‘kiss’ the Sample.

Figure 3. Delayed Match Retrieval (DMR) Test trial.

Figure 3

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Eye movements were analyzed during the 4-second response interval, after the Sample was exposed. We measured performance based on which card (Match or non-Match) was fixated first and the proportion of time spent looking at the correct (Match) card. At the end of the response interval, the Match card was revealed simultaneously with one of three possible reward animations. These animations were so brief (167 ms) that the infant had to have made an anticipatory eye movement in order to fixate it. (For the entire test trial sequence, please see Supplemental Movie 1 online.)

Trials either had the star and swirl serving in the roles of Sample/Match and non-Match, or the tree and smiley face. We only used these two pairs of objects throughout the experiment to introduce proactive interference, reducing the usefulness of long-term memories. This is a manipulation that has been used in the adult VWM literature (Hartshorne, 2008; Makovski & Jiang, 2008). The stimulus pair (red/swirl or tree/face), the order of exposure of the Match and non-Match cards, which of the three cards were in which position (top, left bottom, and right bottom, see Figure 1b), and the identity of the Match were all randomized across trials in a block. The total length of a test trial was 19 seconds.

In each block of 16 trials, infants were first shown the four familiarization trials followed by 12 test trials with three attention-grabber sequences mixed in (where all four types of cards (Figure 1a) were shown jumping up and down). The total length of the block was 5 minutes. Infants ran two blocks of trials with a 3–5 minute break in between. Infants were re-calibrated before the second block. All events were accompanied by sound effects to maintain engagement.

Data analysis

To measure gaze behavior, we defined two identical rectangular Areas of Interest (AOI’s, size: 7×9 deg) around the Match and non-Match cards (Figure 1b). Using these data, we determined infants’ choice between the (correct) Match and the (incorrect) non-Match card on each trial, during the 4-second response interval while both were face-down. If the infant did not fixate either of the two AOI’s during the response interval, the trial was excluded from analysis.

Participants should be motivated to use remembered information to maximize their chances of fixating the reward animation, i.e. to look at the Match card as quickly and accurately as possible — and to linger there — in anticipation of the reward. This ability, then, should be captured by seeing which card they look at first (i.e. percent correct performance, the percent of trials where the infant only fixated the Match, or fixated the Match before the non-Match), and which card they look at longest (i.e. percent looking time, the relative proportion of time spent fixating the Match card: time_on_Match/(time_on_Match + time_on_non-Match)); these form our two dependent variables. We also analyzed the average2 first look latency, to the Match versus the non-Match, to capture the time it takes for an infant to make a decision.

Results

294 and 244 trials were presented to the younger and the older group, respectively. The number of ‘valid’ trials — where infants fixated either the Match or the non-Match cards during the response interval — was 179 (61% of all trials) in the 8-month-old group and 136 (56% of all trials) in the 10-month-old group. The average number of valid trials did not differ between the two groups: M8months = 12.78 trials, SD = 5.45, range = 6–24; M10months= 11.17 trials, SD = 3.90, range = 7–20, Cohen’s d = 0.340, t24 = 0.857, p = n.s.). (All reported t-tests are two-tailed.)

Main results based on first looks

To assess percent correct performance, we used a univariate ANCOVA with Age group (8- vs. 10-month-olds) and Gender (m/f) as fixed factors (both centered), Number of valid trials as a covariate (centered), and percent correct based on first looks as the dependent variable. This full model showed that the main effect of gender was not significant (p = 0.422; ηp2 = 0.031), so this factor was dropped from further analyses. The resultant model shows a significant main effect of Age group (F1 = 8.09, p = 0.009, ηp2 = 0.269). The main effect of Number of valid trials and the interaction between the two factors was not significant (F1 = 3.80, p = 0.064, ηp2 = 0.147; F1 = 3.21, p = 0.087, ηp2 = 0.127, respectively).

Planned comparisons of percent correct performance showed that 10-month-olds significantly outperformed 8-month-olds (M10months = 61.66%, SD = 15.2, M8months = 45.45%, SD = 11.4, d = 1.207, t24 = 3.10, p < 0.005, two-tailed) and that performance was significantly above chance in the older, but not in the younger age group (d = 0.767, t11 = 2.659, p = 0.022; d < 0.01, t13 = −1.495, p = 0.159, respectively) (see Figure 4a).

Figure 4. DMR results.

Figure 4

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The figure shows (a) the average percent correct responses (first looks to the Match) during the response interval and (b) average percent of looking time spent on the correct (Match) card during the response interval, in the two age groups. Overall, 10-month-old infants chose the correct Match card significantly above chance, while 8-month-old infants’ performance was at chance.

Average first look latency to the Match versus the non-Match was not different in either of the age groups (8-month-olds, Mmatch = 1.55 s, SD = 0.47, Mnon-Match = 1.42 s; SD = 0.35, d = 0.301, t13 = 0.834, p = n.s.; 10-month-olds, Mmatch = 1.44 s, SD = 0.40, Mnon-Match = 1.39 s, SD = 0.63, d = 0.080, t11 = 0.17, p = n.s.); infants took no longer to make an incorrect decision than a correct one.

Main results based on percent looking time

Mirroring our main results, planned comparisons showed that percent looking time (to the Match) was significantly above chance in the older, but not in the younger age group (M10months = 60.47%, SD = 14.7, d = 0.712, t11 = 2.472, p = 0.031; M8months = 51.69%, SD = 12.6, d = 0.134, t13 = 0.501, p = n.s., see Figure 4b). The difference between the two groups did not reach significance (d = 0.642, t24 = 1.641, p = 0.114). Given the length of our response interval (4 s, which included exposition of the Sample), infants often did not have time to look at both target cards, therefore it is not surprising that measures based on first looks and looking time are tightly coupled (r = 0.844, p = 0.0001).

The effect of learning

In order to examine learning trends, we compared percent correct performance in the first vs. the second block of trials. (Three infants in each age group did not have data in their second block, leaving 9 infants in the older and 11 infants in the younger group for this within-subject comparison.) A univariate ANOVA with Age group (8- vs. 10-month-olds) and Block (first/second) as fixed factors was conducted. The main effects were not significant (F1 = 2.618, p = 0.114, ηp2 = 0.068; F1 = 0.813, p = n.s., ηp2= 0.022, respectively), but there was a significant interaction between the two factors (F1 = 4.862, p = 0.034, ηp2 = 0.119). Planned comparisons showed that younger infants’ performance significantly increased over time (M8months, Block1 = 39.63%, SD = 15.8, M8months, Block2 = 61.55%, SD = 21.8, d = 1.151, t10 = 2.491, p = 0.032, while older infants’ did not (M10months, Block1 = 66.60%, SD = 18.2, M10months, Block2 = 57.41%, SD = 31.3, d = 0.359, t8 = −0.966, p = n.s., see Figure 5a). The same planned comparisons were conducted with percent looking time, yielding essentially identical results (see Figure 5b).

Figure 5. Learning trends.

Figure 5

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8-month-old infants’ performance significantly increased along both of our measures of performance (a, b), from the first to the second block of trials, while 10-month-olds’ performance remained stable.

Discussion

We developed a novel, non-verbal, anticipation-based Visual Working Memory paradigm to measure memory for object-location bindings: Delayed Match Retrieval (DMR; an inversion of Delayed Match-to-Sample, with inspiration from the game Memory). Success in DMR requires that participants maintain and use what is where information in VWM3. We found that 10-month-old infants remembered the object-location bindings for two objects. Overall, 8-month-olds’ performance was at chance, but showed a robust learning trend. The results of the younger infants are very intriguing; they may also have this ability, but may require more training to acquire the ‘matching’ rule. Further studies are planned to investigate this.

Our pattern of results is consistent with previous novelty-based studies of infants’ VWM capacity for object-location bindings (Oakes et al., 2006; Kaldy & Leslie, 2005). DMR provides novel insight into VWM as it overcomes some of the limitations of novelty-based tests. Compared to Violation-of-Expectation paradigms that measure passive gaze responses to novelty, this paradigm presents a more challenging, arguably more ecologically relevant test, as it requires online predictions and active localization based on remembered information. (And this information need not be strictly visual. DMR could be used to investigate how auditory information is integrated with object representations4. For example, would verbal labels help infants retain object-location bindings in our task? This would be a particularly interesting question to investigate in younger, 8-month-old infants.)

Most tests of visual short-term and working memory are either tailored for infants (4–12-month-olds, change detection with two streams (e.g. Ross-Sheehy et al., 2003), Visual Paired Comparison (e.g. Rose et al., 2001), Violation-of-Expectation (e.g. Kaldy & Leslie, 2005)), for young toddlers (12–20-month-olds, reaching and cracker choice tasks; e.g. Feigenson & Carey, 2005) or for preschool-age children (3–5-year-olds, change detection task; e.g. Simmering, 2012). Novelty-based paradigms for infants are notoriously hard to implement in toddlers; creating a “toddler gap”. DMR is readily scaled-up for toddlers and older children, for instance by increasing the number of cards or the similarity of objects (for this, we have developed methods for ‘calibrating’ stimuli along different feature dimensions: Kaldy, Blaser, & Leslie, 2006; Kaldy & Blaser, 2009; 2013). Indeed, an ongoing study using DMR with 21-month-olds is currently underway in our laboratory (O’Grady, Guillory, Blaser, & Kaldy, 2015) and preliminary findings show that the task is sufficiently engaging for toddlers. Bridging the toddler gap is also important for future longitudinal studies. Such studies hold a particularly important promise since individual differences in VWM show remarkable stability in early development (Bell & Wolfe, 2007) and VWM capacity highly correlates with non-verbal IQ in children (Cowan, Fristoe, Elliott, Brunner, & Saults, 2006). We believe that DMR is particularly well suited for tracking individual differences in infancy and beyond.

Supplementary Material

Smov
Download video file (10MB, mp4)

Research Highlights.

  • Here we introduce a novel paradigm to test infants’ Visual Working Memory (VWM) using anticipatory gaze responses.

  • Our paradigm improves on current approaches that are based on the novelty preference by encouraging participants (through rewards) to make online predictions and actively localize objects based on remembered information.

  • 10-month-olds were able to reliably maintain two object-location bindings over a 1.5 s delay. 8-month-olds showed a robust learning trend.

  • Our paradigm is well suited for longitudinal studies of VWM development as it is readily ‘scaled-up’ to test toddlers, older children or atypically developing, language-delayed populations without modification.

Acknowledgments

This research was supported by National Institutes of Health Grant 2R15EY017985 awarded to EB and ZK. Preliminary results from this study were presented at the Biennial Meeting of the International Society on Infant Studies in Minneapolis, MN, in June, 2012 (Kaldy, Blaser, & Biondi, 2012). We would like to thank Marisa Biondi, Shaun O’Grady, and other members of the UMass Boston Baby Lab for their help with data collection.

Footnotes

1

This response interval is longer than is typical in anticipatory eye-movement paradigms. We had conducted a pilot study with a shorter (1.6 s) interval and found that many trials were lost due to the infants lingering on the just-exposed Sample and therefore not having sufficient time to fixate the Match and/or non-Match card before the response interval ended. We extended this interval to be at least 3x the standard deviation of the mean latency of first fixation (to a valid AOI).

2

Trial-by-trial paired comparison of fixation latency to the Match vs. the non-Match cannot be conducted in the majority of trials, since infants typically only looked at one of the two target cards.

3

We would like to note that there is a potential strategy to aid performance that does not require memorizing all object-location bindings. With two cards, the participant could memorize the object-location binding for just one of them and then when the Sample is exposed, use process-of-elimination or disjunctive syllogism. We believe that this strategy is more cognitively challenging than remembering the locations of both objects. In any case, it is likely not available at 10 months of age. The mutual exclusivity bias in word learning (Markman, 1990; Merriman & Bowman, 1989), has similar reasoning requirements, and in a looking time paradigm, only 17-, but not 14-month-olds, were able to apply this strategy (Halberda, 2003).

4

We would like to thank one of our anonymous reviewers for this suggestion.

References

  1. Albareda-Castellot B, Pons F, Sebastián-Gallés N. The acquisition of phonetic categories in bilingual infants: new data from an anticipatory eye movement paradigm. Developmental Science. 2011;14:395–401. doi: 10.1111/j.1467-7687.2010.00989.x. [DOI] [PubMed] [Google Scholar]
  2. Aslin RN. Infant eyes: A window on cognitive development. Infancy. 2012;17:126–140. doi: 10.1111/j.1532-7078.2011.00097.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
  3. Baillargeon R, Spelke ES, Wasserman S. Object permanence in five-month-old infants. Cognition. 1985;20:191–208. doi: 10.1016/0010-0277(85)90008-3. [DOI] [PubMed] [Google Scholar]
  4. Bell MA, Wolfe CD. Changes in brain functioning from infancy to early childhood: evidence from EEG power and coherence during working memory tasks. Developmental Neuropsychology. 2007;31:21–38. doi: 10.1207/s15326942dn3101_2. [DOI] [PubMed] [Google Scholar]
  5. Cowan N, Fristoe NM, Elliott EM, Brunner RP, Saults JS. Scope of attention, control of attention, and intelligence in children and adults. Memory & Cognition. 2006;34:1754–1768. doi: 10.3758/bf03195936. [DOI] [PMC free article] [PubMed] [Google Scholar]
  6. Diamond A. Rate of maturation of the hippocampus and the developmental progression of children’s performance on the delayed nonmatching to sample and visual paired comparison tasks. Annals of the New York Academy of Sciences. 1990;608:394–426. doi: 10.1111/j.1749-6632.1990.tb48904.x. [DOI] [PubMed] [Google Scholar]
  7. Diamond A, Churchland A, Cruess L, Kirkham NZ. Early developments in the ability to understand the relation between stimulus and reward. Developmental Psychology. 1999;35:1507–17. doi: 10.1037//0012-1649.35.6.1507. [DOI] [PubMed] [Google Scholar]
  8. Overman WH. Performance on traditional matching to sample, non-matching to sample, and object discrimination tasks by 12- to 32-month old children: a developmental progression. Annals of the New York Academy of Sciences. 1990;608:365–393. doi: 10.1111/j.1749-6632.1990.tb48903.x. [DOI] [PubMed] [Google Scholar]
  9. Fagan JF. Memory in the infant. Journal of Experimental Child Psychology. 1970;9:217–226. doi: 10.1016/0022-0965(70)90087-1. [DOI] [PubMed] [Google Scholar]
  10. Fagan JF. Infant recognition memory: studies in forgetting. Child Development. 1977;48:68–78. doi: 10.1111/j.1467-8624.1977.tb04244.x. [DOI] [PubMed] [Google Scholar]
  11. Falck-Ytter T, Gredebäck G, von Hofsten C. Infants predict other people’s action goals. Nature Neuroscience. 2006;9:878–879. doi: 10.1038/nn1729. [DOI] [PubMed] [Google Scholar]
  12. Fantz RL. Visual experience in infants: decreased attention to familiar patterns relative to novel ones. Science. 1964;146:668–670. doi: 10.1126/science.146.3644.668. [DOI] [PubMed] [Google Scholar]
  13. Feigenson L, Carey S. On the limits of infants’ quantification of small object arrays. Cognition. 2005;97:295–313. doi: 10.1016/j.cognition.2004.09.010. [DOI] [PubMed] [Google Scholar]
  14. Halberda J. The development of a word-learning strategy. Cognition. 2003;87:B23–B34. doi: 10.1016/s0010-0277(02)00186-5. [DOI] [PubMed] [Google Scholar]
  15. Hartshorne JK. Visual working memory capacity and proactive interference. PLoS ONE. 2008;3:e2716. doi: 10.1371/journal.pone.0002716. [DOI] [PMC free article] [PubMed] [Google Scholar]
  16. Hollingworth A, Rasmussen IP. Binding objects to locations: The relationship between object files and visual working memory. Journal of Experimental Psychology: Human Perception and Performance. 2010;36:543–564. doi: 10.1037/a0017836. [DOI] [PMC free article] [PubMed] [Google Scholar]
  17. Johnson SP, Amso D, Slemmer JA. Development of object concepts in infancy: evidence for early learning in an eye-tracking paradigm. Proceedings of the National Academy of Sciences of the United States of America. 2003;100:10568–10573. doi: 10.1073/pnas.1630655100. [DOI] [PMC free article] [PubMed] [Google Scholar]
  18. Kahneman D, Treisman A, Gibbs BJ. The reviewing of object files: object-specific integration of information. Cognitive Psychology. 1992;24:175–219. doi: 10.1016/0010-0285(92)90007-o. [DOI] [PubMed] [Google Scholar]
  19. Kaldy Z, Blaser E. How to compare apples and oranges: Infants’ object identification tested with equally salient shape, luminance and color changes. Infancy. 2009;14:222–243. doi: 10.1080/15250000802707088. [DOI] [PMC free article] [PubMed] [Google Scholar]
  20. Kaldy Z, Blaser E. Red to green or fast to slow? Infants’ Visual Working Memory for ‘Just Salient Differences’. Child Development. 2013;84:1855–1862. doi: 10.1111/cdev.12086. [DOI] [PMC free article] [PubMed] [Google Scholar]
  21. Kaldy Z, Blaser E, Biondi M. Can infants play the “Memory” game?. Poster presented at the International Conference on Infant Studies; June 6–10, 2012; Minneapolis, MN. 2012. [Google Scholar]
  22. Kaldy Z, Blaser E, Leslie AM. A new method for calibrating perceptual salience across dimensions in infants: The case of color vs. luminance. Developmental Science. 2006;9:482–489. doi: 10.1111/j.1467-7687.2006.00515.x. [DOI] [PubMed] [Google Scholar]
  23. Kaldy Z, Leslie A. A memory span of one? Object identification in 6.5-month-old infants. Cognition. 2005;57:153–177. doi: 10.1016/j.cognition.2004.09.009. [DOI] [PubMed] [Google Scholar]
  24. Kaldy Z, Leslie AM. Identification of objects in 9-month-old infants: integrating ‘what’ and ‘where’ information. Developmental Science. 2003;6:360–373. [Google Scholar]
  25. Kavšek M. The comparator model of infant visual habituation and dishabituation: recent insights. Developmental Psychobiology. 2013;55:793–808. doi: 10.1002/dev.21081. [DOI] [PubMed] [Google Scholar]
  26. Kovács AM, Mehler J. Cognitive gains in 7-month-old bilingual infants. Proceedings of the National Academy of Sciences of the USA. 2009a;106:6556–60. doi: 10.1073/pnas.0811323106. [DOI] [PMC free article] [PubMed] [Google Scholar]
  27. Kovács AM, Mehler J. Flexible learning of multiple speech structures in bilingual infants. Science. 2009b;325:611–612. doi: 10.1126/science.1173947. [DOI] [PubMed] [Google Scholar]
  28. Leslie AM, Xu F, Tremoulet PD, Scholl BJ. Indexing and the object concept: developing ‘what’ and ‘where’ systems. Trends in Cognitive Sciences. 1998;2:10–18. doi: 10.1016/s1364-6613(97)01113-3. [DOI] [PubMed] [Google Scholar]
  29. Makovski T, Jiang YV. Proactive interference from items previously stored in visual working memory. Memory & Cognition. 2008;36:43–52. doi: 10.3758/mc.36.1.43. [DOI] [PubMed] [Google Scholar]
  30. Mareschal D, Johnson MH. The ‘what’ and ‘where’ of object representations in infancy. Cognition. 2003;88:259–276. doi: 10.1016/s0010-0277(03)00039-8. [DOI] [PubMed] [Google Scholar]
  31. Markman EM. Constraints children place on word meanings. Cognitive Science. 1990;14:57–77. [Google Scholar]
  32. McMurray B, Aslin RN. Anticipatory eye movements reveal infants’ auditory and visual categories. Infancy. 2004;6:203–229. doi: 10.1207/s15327078in0602_4. [DOI] [PubMed] [Google Scholar]
  33. Merriman WE, Stevenson CM. Restricting a familiar name in response to learning a new one: Evidence for the mutual exclusivity bias in young two-year-olds. Child Development. 1997;68:211–228. [PubMed] [Google Scholar]
  34. Mervis CB, Bertrand J. Acquisition of the novel name–nameless category (N3C) principle. Child Development. 1994;65:1646–1662. doi: 10.1111/j.1467-8624.1994.tb00840.x. [DOI] [PubMed] [Google Scholar]
  35. Newcombe N, Huttenlocher J, Learmonth A. Infants’ coding of location in continuous space. Infant Behavior & Development. 1999;22:483–510. [Google Scholar]
  36. O’Grady S, Guillory SB, Blaser E, Kaldy Z. Young toddlers pass an anticipatory version of the invisible displacement task. Poster presented at the Biennial Meeting of the Society for Research in Child Development; March 19–21, 2015; Philadelphia, PA. 2015. [Google Scholar]
  37. Oakes LM, Ross-Sheehy S, Luck SJ. Rapid development of feature binding in visual short-term memory. Psychological Science. 2006;17:781–787. doi: 10.1111/j.1467-9280.2006.01782.x. [DOI] [PubMed] [Google Scholar]
  38. Overman WH. Performance on traditional matching to sample, non-matching to sample, and object discrimination tasks by 12- to 32-month old children: a developmental progression. Annals of the New York Academy of Sciences. 1990;608:365–93. doi: 10.1111/j.1749-6632.1990.tb48903.x. [DOI] [PubMed] [Google Scholar]
  39. Pancratz CN, Cohen LB. Recovery of habituation in infants. Journal of Experimental Child Psychology. 1970;9:208–216. doi: 10.1016/0022-0965(70)90086-x. [DOI] [PubMed] [Google Scholar]
  40. Pelphrey KA, Reznick JS, Goldman B, Sasson N, Morrow J, Donahoe A, Hodgson K. Development of visuospatial short-term memory in the second half of the 1st year. Developmental Psychology. 2004;40:836–51. doi: 10.1037/0012-1649.40.5.836. [DOI] [PubMed] [Google Scholar]
  41. Reznick JS. Working memory in infants and toddlers. In: Oakes LM, Bauer PJ, editors. Short- and long-term memory in infancy and early childhood. Oxford: Oxford University Press; 2007. pp. 3–26. [Google Scholar]
  42. Reznick JS, Morrow JD, Goldman BD, Snyder J. The onset of working memory in Infants. Infancy. 2004;6:145–154. [Google Scholar]
  43. Rose SA. Developmental changes in infants’ retention of visual stimuli. Child Development. 1981;52:227–233. [PubMed] [Google Scholar]
  44. Rose SA, Feldman JF, Jankowski JJ. Visual short-term memory in the first year of life: capacity and recency effects. Developmental Psychology. 2001;37:539–549. doi: 10.1037//0012-1649.37.4.539. [DOI] [PubMed] [Google Scholar]
  45. Rose SA, Feldman JF, Jankowski JJ. Infant visual recognition memory. Developmental Review. 2004;24:74–100. doi: 10.1037/0012-1649.39.3.563. [DOI] [PubMed] [Google Scholar]
  46. Ross-Sheehy S, Oakes LM, Luck SJ. The development of visual short-term memory capacity in infants. Child Development. 2003;74:1807–1822. doi: 10.1046/j.1467-8624.2003.00639.x. [DOI] [PubMed] [Google Scholar]
  47. Rovee-Collier CK, Gekoski MJ. The economics of infancy: a review of conjugate reinforcement. Advances in Child Development & Behavior. 1979;13:195–255. doi: 10.1016/s0065-2407(08)60348-1. [DOI] [PubMed] [Google Scholar]
  48. Simmering VR. The development of visual working memory capacity during early childhood. Journal of Experimental Child Psychology. 2012;111:695–707. doi: 10.1016/j.jecp.2011.10.007. [DOI] [PubMed] [Google Scholar]
  49. Siqueland ER, Lipsitt LP. Conditioned head-turning in human newborns. Journal of Experimental Child Psychology. 1966;3:356–76. doi: 10.1016/0022-0965(66)90080-4. [DOI] [PubMed] [Google Scholar]
  50. Slater A, Earle DC, Morison V, Rose D. Pattern preferences at birth and their interaction with habituation-induced novelty preferences. Journal of Experimental Child Psychology. 1985;39:7–54. doi: 10.1016/0022-0965(85)90028-1. [DOI] [PubMed] [Google Scholar]
  51. Southgate V, Senju A, Csibra G. Action anticipation through attribution of false belief by 2-year-olds. Psychological Science. 2007;18:587–592. doi: 10.1111/j.1467-9280.2007.01944.x. [DOI] [PubMed] [Google Scholar]
  52. Voyer D, Postma A, Brake B, Imperato-McGinley J. Gender differences in object location memory: a meta-analysis. Psychonomical Bulletin & Review. 2007;14:23–38. doi: 10.3758/bf03194024. [DOI] [PubMed] [Google Scholar]
  53. Weinstein B. Matching-from-sample by rhesus monkeys and by children. Journal of Comparative Psychology. 1941;31:195. [Google Scholar]
  54. Wilcox T, Alexander GM, Wheeler L, Norvell JM. Sex differences during visual scanning of occlusion events in infants. Developmental Psychology. 2012;48:1091–1105. doi: 10.1037/a0026529. [DOI] [PMC free article] [PubMed] [Google Scholar]

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