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. Author manuscript; available in PMC: 2025 Nov 1.
Published in final edited form as: Infancy. 2024 Sep 22;29(6):1002–1021. doi: 10.1111/infa.12624

Body Structure Processing and Attentional Patterns in Infancy and Adulthood

Rachel Jubran 1, Hannah White 2, Alison Heck 3, Alyson Chroust 4, Ramesh S Bhatt 5
PMCID: PMC11533482  NIHMSID: NIHMS2028234  PMID: 39307918

Abstract

Infants are sensitive to distortions to the global configurations of bodies by 3.5 months of age, suggesting an early onset of body knowledge. It is unclear, however, whether such sensitivity indicates knowledge of the location of specific body parts or solely reflects sensitivity to the overall gestalt of bodies. This study addressed this issue by examining whether, like adults, infants attend to specific locations where body parts have been reorganized. Results show that adults and 5-month-olds, but not 3.5-month-olds, allocated more attention to the body joint areas (e.g., where the arm connects to the shoulder) that were reorganized versus ones that were typical. To examine whether this kind of processing is driven by low-level features, 5-month-olds were tested on images in which the head was removed. Infants no longer exhibited differential scanning of typical versus reorganized bodies. Results suggest that 5-month-olds are sensitive to the location of body parts, thereby demonstrating adult-like response patterns consistent with early expertise in body processing. The contrasting failure of 3.5-month-olds to exhibit sensitivity to the reorganization suggests a developmental change between these ages.

While many studies document the development of facial processing in infancy (e.g., Bhatt et al., 2005 & Quinn et al., 2019), fewer studies examine infants’ body knowledge development. The human body is important for conveying a great variety of social information (Aviezer et al., 2012; Fast, 1988). For instance, bodies relay people’s goals and desires, sometimes unintentionally, through “body language” (Fast, 1988). Bodies are also good indicators of emotion, and in some cases, they are even better at conveying peak emotions than faces (Aviezer et al., 2012). Moreover, bodies are larger than faces, and therefore can be processed from a greater distance, making the ability to obtain socially relevant information from bodies highly adaptive.

The question then arises as to how bodies are recognized and how information from them is processed early in life. One aspect of successful body processing is sensitivity to structural information (Slaughter et al., 2012). The current study aims to determine the nature and developmental trajectory of infants’ representation of the human body. Specifically, we examined whether infants at different ages attend to regions of body images that have been reorganized in such a manner that body parts are located in different places than in typical humans. If infants attend to the reorganized locations, then it would suggest that their representation of bodies is highly specific and includes detailed information about the location of body parts. If older infants exhibit attention to those areas but younger infants do not, it would suggest a developmental change in the specific representation of the location of body parts in the overall structure of the human body. Surprisingly, it is unknown whether even adults attend to locations where body parts have been reorganized. Therefore, we addressed that issue in the current experiments by using the same body stimuli with adults and infants. If adults do look longer at locations of the body that have been reorganized, then we have a benchmark for the study of the development of body knowledge.

Theories of Body Knowledge Development

While there is a general consensus that adults exhibit expert processing of bodies, extant theories pertaining to the development of such expertise are often in conflict (Bhatt et al., 2016; Marshall & Meltzoff, 2015; Meltzoff, 2011; Slaughter & Heron, 2004; Slaughter et al., 2012). The theory proposed by Slaughter and colleagues (Slaughter & Heron, 2004; Slaughter et al., 2012) argues that visuo-spatial knowledge of bodies is slow to develop and that it takes until the second year of life for infants to exhibit robust body knowledge. Slaughter and colleagues (2012) also posit that while face knowledge is innate or served by a dedicated mechanism that is biologically specified, knowledge about bodies is acquired gradually through general learning mechanisms, and adults become experts through high levels of exposure over time. Such a theory would suggest that sensitivity to structural information in bodies and the location of individual parts would not be evident early in life.

In contrast, the “like-me” theory states that body knowledge is either innate or develops early in life due to observation and imitation (Marshall & Meltzoff, 2015; Meltzoff, 2011). Specifically, newborns isolate certain organs from birth (Meltzoff & Moore, 1997), and after observing a particular gesture or movement, newborns activate that same area on their own body (Meltzoff, 2011). Additionally, Meltzoff and colleagues (Meltzoff, Murray et al., 2018; Meltzoff, Ramírez et al., 2018) report systematic neural responses in infants as young as 60 days in response to touch to both their own and others’ body parts (i.e., hand, foot, and lip). As it pertains to the current study, this notion of organ identification early in life suggests that infants as young as 3.5 months of age may allocate their attention to specific regions of change on the body.

Additionally, Bhatt et al. (2016) suggest that body knowledge develops along a similar trajectory as facial knowledge, possibly through a general social cognition system that arms the infant with the ability to process critical social information from a variety of sources, like faces and bodies. Such a mechanism would be highly adaptive as it would allow the infant to maximally benefit from the redundancy of information across various sources.

Bhatt and colleagues (2016) also acknowledge that, rather than a fully integrated social cognition system, early acquisition of body knowledge could emerge through a body-specific knowledge system (i.e., an analog to the face specific processes such as the fusiform face area and/or the CONSPEC/CONLERN mechanisms; Kanwisher et al., 1997; Morton & Johnson, 1991) that benefits from relevant information from the rapidly developing face-processing system. For example, CONSPEC/CONLERN posits that infants’ face preferences are first influenced by an innate mechanism (CONSPEC) based on sensitivity to the relative spatial location of features within a face. Later, with development, a learning mechanism (CONLEARN) enables the infant to more fully develop a concept of the face. It is possible that a similar CONSPEC/CONLEARN system applies to the development of body processing in infancy. Moreover, infants’ face knowledge could facilitate their knowledge of bodies because of the close association through repeated exposure to faces and bodies displaying complementary social information. This would be in line with research that has shown that infants as young as 2 months of age are adept at statistical learning and are able to pick up on patterns of simultaneous exposure and form associations (Kirkham, 2002; Saffran et al., 1996). Thus, Bhatt et al. (2016) and the “like-me” theory proposed by Meltzoff and his colleagues (Marshall & Meltzoff, 2015; Meltzoff, 2011; Meltzoff & Moore, 1997) agree that knowledge about body parts is available early in life.

Previous Research on Configural Processing of Bodies

Higher-level social processing, such as categorization based on sex, race, or emotion, can only occur once an individual is identified as a human. Adults use configural processing to identify human bodies (Reed et al., 2003). Such configural processing was found to be an early step in the processing of bodies based on analyses of the N1 amplitudes of event-related potential (ERP) responses for adults viewing typical and reorganized bodies (Gliga & Dehaene-Lambertz, 2005). In this respect, bodies are like faces in that configural information is important to identify both (Carey, 1992; Diamond & Carey, 1986; Maurer et al., 2002; Reed et al., 2003; Reed et al., 2006; Slaughter & Heron, 2004). Furthermore, deviation from the typical configuration disrupts body processing in adulthood (Reed et al., 2003; Reed et al., 2006). Specifically, Reed and colleagues (2006) found that adults recognize typically configured bodies faster than bodies that have been reorganized.

Like adults, infants are also sensitive to the configuration of the body. Three-month-olds exhibit differing ERP responses to typical versus reorganized bodies, indicating that knowledge of the specific structure of the human body is available early in life (Gliga & Dehaene-Lambertz, 2005). Further, Zieber et al. (2015) found that infants at 3.5 months of age exhibit a preference for bodies that have been reorganized over typically configured bodies, providing further evidence that infants at 3.5 months of age are sensitive to the configuration of bodies, at least at a global level. However, it is not yet known whether infants’ representation of bodies includes knowledge about the location of the specific body parts that make up the human template. In other words, while the studies cited above demonstrate that infants are sensitive to the fact that a body representation was atypical in some way, they do not necessarily indicate whether infants are sensitive to the specific nature of the reorganization, which requires a much more fine-grained level of knowledge. Examining the specificity of infants’ body knowledge at different ages will help us understand the nature of development of body knowledge in infancy. Significant findings in the current study would be consistent with the prior findings that infants are sensitive to body configuration. However, if infants do not attend to specific regions of reorganization, that would indicate that detailed knowledge of the configuration of bodies does not develop until some point after 3.5 months of age, which would be consistent with existing literature on knowledge of faces (e.g., Bhatt et al., 2005).

The Current Study

As noted earlier, Zieber et al. (2015) found that infants at 3.5 months of age are sensitive to the global configuration of bodies. However, it is unknown whether infants are attending to the specific regions on the body that have undergone a reorganization or whether they are responding to changes in the overall outline or gestalt of the body. To address this issue, the current study examined whether infants attend to specific locations of reorganization in body images. We also tested adults in the current study because, to our knowledge, it is unknown whether adults attend to specific regions of body reorganizations. If adults do show a specialized scanning pattern, and infants mirror that pattern, it would be evidence that sensitivity to the specific location of body parts develops early. We tested two different age groups within infancy (3.5-month-olds and 5-month-olds) to document any developmental changes within this age range.

Eye-trackers are commonly used to determine scanning patterns in both, infancy and adulthood (Atkinson et al., 1992; Bronson, 1994; Kovack-Lesh et al., 2014; Morita et al., 2012; White et al., 2018; White et al., 2019) because they are able to provide more detailed gaze information about fixations towards a specific location on a screen. Thus, adults (Experiment 1) and infants (Experiments 2 and 3) were tested using an eye-tracker to determine whether they attend to the specific areas of reorganization (see Figure 1).

Figure 1.

Figure 1.

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Examples of the typical (A) and reorganized (B) stimuli used in Experiments 1 and 2. Each participant saw the typical image four times and the reorganized image four times for a total of eight 12s test trials per stimulus set. Adults viewed all six stimulus sets and infants viewed one of the possible six typical-reorganized body pairs. The colored shapes represent the area of manipulation AOIs. These shapes were not visible to participants. All actors were wearing white shirts and blue jeans. Some models had long sleeves and others had short sleeves.

Two age groups of infants (5-month-olds and 3.5-month-olds) were tested in Experiment 2. This age range was chosen because prior research indicates developmental changes in body knowledge between 3.5 and 5 months of age. For example, Heck and colleagues (2018) found that 5-month-olds match emotional body postures to emotional voices, but 3.5-month-olds failed to do so. Additionally, Hock and colleagues (2016) found that 5-month-olds process body information holistically, as evidenced by superior detection of limb postures in the context of the whole body than in isolation. It is thus possible that, by 5 months, but not 3.5 months, body information processing has reached a level of expertise that is sensitive enough to the structure of bodies to detect changes in the specific location of body parts.

Experiment 3 examined 5-month-old infants’ performance on headless images to ensure that performance in Experiment 2 was not a result of the infants picking up on some low-level features of the stimuli. If performance on the complete images of Experiment 2 was due to low-level features (e.g., symmetry, balance), infants should exhibit a similar pattern of performance on headless images. If, however, infants’ performance on headless bodies is different than on complete bodies, then it would suggest that structural processing of faces and bodies is integrated early in life and that low-level image features are not the basis of performance on the complete bodies.

Experiment 1

Experiment 1 examined the attentional patterns of adults to document the manner in which they allocate their attention to typical versus reorganized bodies. This allowed us to better understand the specificity of adults’ processing of body configurations and served as a benchmark for a developmental analysis. While Reed and colleagues (2006) found that disrupting the first-order spatial relations (e.g., scrambling body part positions) of bodies impacted adults’ recognition of body postures, it is still unknown whether adults attend specifically to locations of parts that have been displaced. Answering this question allowed us to set the stage for the study of infants in the following experiments. Finding that adults do allocate their attention to the specific areas of reorganization in the current study would indicate that they employ a more localized attentional pattern that focuses on the specific changes made to the body (e.g., arms protruding from hips), rather than just responding to the overall gestalt of the body (e.g., top/bottom balance).

Method

Participants

All procedures involving human subjects in this study were approved by the Institutional Review Board at the University of Kentucky. Studies were conducted at the University of Kentucky Infant Memory Lab. A power analysis based on effect sizes (ηp2 = 0.13–0.17) from similar previous studies (Hewig et al., 2008; Nummenmaa et al., 2012) indicated that at least 30 participants would give over 80% power to detect the expected effect. Thus, thirty undergraduate students between the ages of 18 and 22 from the American South (mean age = 19 years old, SD = 1.05; 21 female) were recruited from the psychology department subject pool and participated in this study in exchange for course credit. Most students self-reported their race as White (94%). The remainder reported their race as African American (3%) and Native American/Native Pacific Islander/Hispanic/White (3%). Students’ race at the university was somewhat less diverse than the greater population of the metropolitan area. While this is not necessarily unexpected for data collection with an undergraduate population, it is a limitation of the current study. Participants reported normal or corrected to normal vision and were naïve to the purpose of the research.

Stimuli

The body stimuli used in this experiment were photographs of females on a gray background (see Figure 1). These images were selected because they were similar to those used in previous body processing studies during infancy (Zieber et al., 2015) and allow for the same stimuli to be used across Experiments. The main modification from the images used in Zieber and colleagues (2015) is that the actors in the current stimuli sets were all wearing similarly colored clothing, but the type of body reorganizations remained the same (with the addition of one reorganization type: swapping one arm and one leg). None of the actors wore jewelry, glasses, or hats and makeup was minimal (if applied at all).

To create the stimuli in our study, we started with four images of female actors standing in a neutral position. All body reorganizations were generated using Adobe Photoshop software. Two of the four actor images were used twice for two different kinds of reorganizations to give us a total of six different reorganized images with three types of biologically impossible reorganizations (two with arms attached to the body in the waist area, two with the positions of both arms and legs switched, and two with the positions of one arm and one leg switched). Participants saw each reorganized image as well as each unaltered, typical image four times for a total of 24 typically configured bodies and 24 of their reorganized versions (Figure 1).

Apparatus and Procedure

A Tobii TX300 eye-tracker was used to record participants’ looks. The eye-tracker’s cameras recorded the reflection of an infrared light source on the cornea relative to the pupil from both eyes at a frequency of 300 Hz. The average accuracy of this eye-tracker according to the manufacturer is in the range of .5 to 1 degree, which approximates to a .5–1 cm area on the screen with a viewing distance of 65 cm. The eye-tracker compensates for head movements, which typically result in a temporary accuracy error of approximately 1 degree and a 100 ms recovery time to full tracking ability after movement offset.

Before starting data collection, each adult’s eyes were calibrated using a 9-point calibration procedure in which a moving disc was presented sequentially at nine locations on the screen. The calibration procedure was repeated if calibration was not obtained for both eyes in more than one location. Eye-tracker calibration and stimulus presentation were controlled by Tobii Studio 3.3.1 software (Tobii Technology AB; www.tobii.com). The I-VT (velocity–threshold identification) fixation filter provided within Tobii Studio was used to classify which eye movements were considered to be valid fixations. A fixation was defined as any look that exceeded 60 ms while remaining within a 0.5 radius (Olsen, 2012). This criterion eliminates any noise from the data (e.g., sporadic eye movements). These specific thresholds have been utilized in previous research with similar age groups as those used in current study (Gupta et al., 2022; Hunnius et al., 2011; Papageorgiou et al., 2014; Xiao et al., 2014) and recent work has found fixations defined at this threshold are consistent across time and stimulus (White et al., 2022). Additionally, data from the first 500 ms of each trial were discarded. This adjustment removes artificially inflated looking times to the center of the stimulus as it appears directly behind the attention getter. This criterion is similar to those used in previous studies of body scanning (e.g., Kret et al., 2013; White et al., 2018).

Participants saw each of the six stimulus body pairs (one typical configuration and one reorganized configuration per pair) for a total of 48 12s trials. In each trial, a single image (typical or reorganized) was presented in the center of the screen on a gray background. Half of the trials contained images of typical bodies while the other half displayed images of reorganized bodies. Preceding every trial, an attention-getter consisting of alternating colorful shapes appeared on the screen to direct the participant’s focus to the center of the screen. Once the participant looked toward the attention-getter, the test stimulus appeared in the center of the screen. The image type (typical or reorganized) of the stimulus presented on the first trial was counterbalanced across participants. The stimuli presented on the remaining 47 trials were randomly determined with the constraint that the same image was never presented consecutively more than twice.

Areas of interest (AOIs) were drawn on each body (see Figure 1) where the limbs met the trunk of the typical body and where the limbs met the trunk of the reorganized body (on average, each AOI was 0.22% of the screen). An additional AOI was drawn around the entire body (on average 21.25% of the screen). The AOIs were identical within a stimulus pair (typical, reorganized) seen by a participant; this allowed the direct comparison of fixation durations to each AOI type across stimuli without confounding AOI location with body type.

Results and Discussion

The dependent measure was the percent of total looking to each kind of stimulus (typical or reorganized) that was devoted to the critical limb junctions (see AOIs in Figure 1) where the reorganization took place. This was calculated by dividing the total fixation duration to the joints on each kind of stimulus summed across all 24 presentations (each kind of image was presented 24 times to each participant for a total of 48 trials) by the total fixation duration to the overall stimulus (defined as the AOI around the whole body). The resulting number was then multiplied by 100 to obtain a percent score. An outlier analysis (Tukey, 1977; using SPSS version 29.0) revealed no outliers. A paired samples t-test revealed a significant difference in looking to the joint AOIs on the typical body (M = 5.06%, SD = 3.12) versus the reorganized body (M = 10.67%, SD = 5.16); t(29) = −7.35, p < .001, d = 1.32 (Figure 2). Table 1 contains descriptive information outlining the mean percent of total fixation durations to the head, limbs, and joints on the stimuli in the current study. The calculations for the head and limbs were the same as those used to calculate the total fixation durations to the joints. Adults looked proportionally longer at the locations of reorganization than at the same locations when there was no reorganization. This finding is, to our knowledge, the first to show that adults’ sensitivity to body part reorganization in human images manifests as heightened attention to locations of specific regions of manipulation rather than just responding to the overall gestalt of the body (e.g., top/bottom balance). In addition, this experiment allows us to better understand how infants’ body processing compares to that of adults in the following experiments.

Figure 2.

Figure 2.

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Mean percent of total fixation duration to the joint AOIs exhibited by participants in Experiments 1–3. Standard error bars are presented. ***p < .001 and *p < .05.

Table 1.

Mean percent of total fixation durations (out of all looking to the stimulus) to the head, limbs, and joint AOIs on the typical and reorganized images across all participants in Experiments 1–3.

Looking to Head Looking to Limbs Looking to Joints Looking Elsewhere to Stimulus
Adults (N=30) Typical Images 43.17% 15.59% 5.06% 36.18%
Adults (N=30) Reorganized Images 31.46% 22.21% 10.67% 35.66%
3.5-Month-Olds (N=28) Typical Images 18.47% 16.86% 12.54% 52.13%
3.5-Month-Olds (N=28) Reorganized Images 18.48% 16.70% 10.15% 54.67%
5-Month-Olds (N=30) Typical Images 30.60% 12.72% 4.74% 51.94%
5-Month-Olds (N=30) Reorganized Images 29.00% 10.00% 7.37% 53.63%
5-Month-Olds (N=28) Headless Typical Images 2.99% 25.60% 10.70% 60.71%
5-Month-Olds (N=28) Headless Reorganized Images 5.69% 23.98% 8.87% 61.46%
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Experiment 2

In Experiment 2, we examined whether 3.5- and 5-month-old infants exhibit differential scanning of typical versus reorganized body images similar to the adults in Experiment 1. This allowed us to assess how fine-tuned infants’ knowledge of bodies is early in life by documenting the way in which they allocate their attention to specific areas within the body. These age groups were chosen because previous research found that they exhibit an overall preference between a reorganized body and a typical body (Zieber et al., 2015), thereby indicating that they are sensitive to at least the global configuration of the human body. However, it is unclear from prior studies whether infants at these ages are sensitive enough to the typical configuration of the human body to display systematic attention to specific locations of manipulation in reorganized body images. Finding that infants do allocate their attention differently to reorganization locations would indicate that young infants, like adults, are sensitive to the specific changes made to the body (e.g., arms protruding from hips), rather than just responding to the overall gestalt of the body (e.g., top/bottom balance). Such an outcome would suggest that infants are sensitive to the location of specific body parts such as arms and legs. In contrast, if there is no allocation of attention to reorganized locations, then it would suggest that infants’ sensitivity to specific body part locations does not direct their visual attention at 3.5 and 5 months of age. It is also possible that the older infants will allocate their attention differently, while the younger infants will not. This would suggest the development of a more detailed, adult-like approach to seeking information from human bodies as evidenced by their scanning patterns between 3.5 and 5 months of age.

Method

Participants

The present study was conducted according to guidelines laid down in the Declaration of Helsinki, with written informed consent obtained from a parent or guardian for each child before any assessment or data collection. A power analysis based on the average effect size (d = .597) in a prior study (White et al., 2018) that used the same procedure as the one utilized in the current experiment indicated that at least 25 infants were needed in each group to detect a large effect with 80% power. Thus, thirty 3.5-month-old infants (mean age = 104 days, SD = 10.10; 12 female) and thirty 5-month-old infants (mean age = 152 days, SD = 4.48; 16 female) participated in this study. Data from additional 3.5-month-olds were excluded for looking at the stimuli for less than 20% of the duration of the study (n = 4) and not looking at all of the areas of interest (n = 2). Data from additional 5-month-old infants were excluded for looking at the stimuli for less than 20% of the duration of the study (n = 10) and for not looking to all of the areas of interest (n = 1). To our knowledge, there is no single consensus on what thresholds should be used for infants with low amounts of looking in eye-tracking procedures. Twenty percent has been successfully used in a variety of eye-tracking paradigms (Heck et al., 2018; White et al., 2018; White et al., 2019), but is not universal. To ensure that our results are not dependent on a single arbitrary threshold, we conducted a sensitivity analysis. The pattern of results was maintained when examining all infants with >10% looking.1 Thus, the findings do not seem to be due to selection bias. Infants were recruited through birth announcements in the local newspaper and a local hospital. A majority of the parents reported their infants’ race as White (75%). The remainder reported their infants’ race as African American (8%), Asian (2%) and Mixed Race (15%), which was representative of the surrounding area.

Stimuli

The body stimuli used in this experiment were identical to those used in Experiment 1; however, each infant was tested on a single pair of images (one type of biologically-impossible reorganization), a typically configured body and its reorganized version (Figure 1), rather than all six pairs like the adults saw in Experiment 1. Each of the 6 stimulus sets were seen by 5 different infants. Across all infants, the image type (typical or reorganized) of the stimulus presented on the first trial was counterbalanced. The stimuli presented on the remaining seven trials were randomly determined with the constraint that the same image was never presented consecutively more than twice.

Apparatus and Procedure

Infants were seated approximately 65 cm in front of 58 cm computer monitor in a darkened chamber. They were seated on the lap of a parent, who wore opaque glasses that prevented them from seeing the images on the screen and potentially biasing infants’ looking patterns. Parents were instructed to not direct their infant’s looking in any way.

This study used the same Tobii TX300 eye-tracker that was used in Experiment 1. Before starting data collection, each infant’s eyes were calibrated using a 5-point infant calibration procedure in which a 23.04 cm2 red and yellow rattle coupled with a rhythmic sound was presented sequentially at five locations on the screen (i.e., the four corners and the center). An experimenter controlled the calibration process with a key press to advance to the next calibration point after the infant was judged (via a live video feed) to be looking at the current calibration point. The calibration procedure was repeated if calibration was not obtained for both eyes in more than one location.

The stimuli, AOIs, and procedure were the same as those used in Experiment 1 (see Figure 1) except that infants were tested on only one of the six stimulus body pairs for a total of eight 12s trials. As was the case in Experiment 1, a single image (typical or reorganized) was presented in the center of the screen on a gray background on each trial. Half of the trials contained images of typical bodies while the other half displayed images of reorganized bodies. Infants in the current experiment observed an attention-getter consisting of alternating colorful shapes before each trial. This was meant to direct the infant’s focus to the center of the screen. Once the infant looked toward the attention-getter (as judged by the experimenter), the test stimulus appeared in the center of the screen.

Results and Discussion

The results were analyzed in the same manner as in Experiment 1. An outlier analysis (Tukey, 1977) for the dependent variable of interest (percentage scores) was run. A boxplot analysis in SPSS revealed that two 3.5-month-old infants in the current condition had scores greater than 1.5 times the interquartile range above the 75th quartile. Thus, these scores were not included in the following analysis. This is consistent with previous literature (Damm et al., 2019; Doyle et al., 2021; Saint et al., 2017; White et al., 2019). There were no outliers in the 5-month-old age group.

An ANOVA with joint AOIs (typical and reorganized) as within-subjects factors and Age (3.5-, 5-month-olds, and adults) as between-subjects factors revealed a significant main effect of joint AOIs whereby participants fixated longer on the reorganized versus typical stimuli, F(1,85) = 8.393, p = .005, ηp2 = .090 as well as a significant main effect of age whereby participants fixated longer on the areas of reorganization dependent upon their age F(2,85) = 8.511, p < .001, ηp2 = .167, however, these effects were qualified by a significant joint AOI X Age interaction, F(2, 85) = 11.834, p < .001, ηp2 = .218. This interaction indicates that the distribution of attention to the joint areas for typical versus reorganized bodies differs systematically by age. To follow up the significant joint AOI x Age interaction, we compared each combination of ages individually.

When following up on the joint AOI x Age interaction by comparing two age groups at a time, there was a significant joint AOI x Age interaction in all comparisons (3.5- and 5-month-olds F(1,56) = 7.073, p = .010, ηp2 = .112; 3.5-month-olds and adults F(1, 56) = 21.879, p < .001, ηp2 = .281; and 5-month-olds and adults F(1, 58) = 5.135, p = .027, ηp2 = .081). These interactions indicate that the distribution of attention to the joint areas for typical versus reorganized bodies differs systematically with age. A paired samples t-test revealed no difference in looking to the joint AOIs on the typical body for the 3.5-month-olds (M = 12.54%, SD = 7.25) versus the reorganized body (M = 10.15%, SD = 8.56), t(27) = 1.52, p = .140, d = .29 (Figure 2). Thus, infants at 3.5 months of age failed to exhibit differential scanning to the reorganized locations of body images. However, like adults in Experiment 1, 5-month-old infants looked proportionally less at the joint AOIs on the typical body (M = 4.74%, SD = 3.76) versus on the reorganized body (M = 7.37%, SD = 5.80); t(29) = −2.43, p = .021, d = .54 (Figure 2).

Even though 5-month-olds and adults differ in the magnitude of effect, they show the same pattern of heightened attention to areas of reorganization. Specifically, the results indicate that 5-month-olds fixate longer on the joint areas of a reorganized body than on the typical body, suggesting that they recognize that the reorganized body part is no longer in its canonical location. Thus, unlike 3.5-month-olds in this experiment, 5-month-olds exhibited sensitivity to the specific location of body parts in human images just as adults did in Experiment 1. This suggests the development of a more detailed, adult-like approach to seeking information from human bodies as evidenced by their scanning patterns between 3.5 and 5 months of age. Furthermore, this evidence of differential scanning within the first half year of life supports the proposal by Bhatt et al. (2016) and Meltzoff and colleagues (Marshall & Meltzoff, 2015; Meltzoff, 2011; Meltzoff & Moore, 1997) that body knowledge develops quite early in life.

Combined with the results of the previous study by Zieber and colleagues (2015), these results suggest that although 3.5-month-old infants discriminate between typical and reorganized bodies, they do not seem to be sensitive to the specific locations of change, at least as reflected by less organized scanning patterns. This finding suggests that 3.5-month-olds’ representation of human bodies may be more responsive to changes in overall gestalt patterns than to locations of specific body parts such as arms and legs.

Experiment 3

Experiment 3 tested infants on headless bodies which served as a control condition in relation to Experiment 2 because the reorganizations were the same as on the whole body (headed) stimuli used in that experiment. This allowed us to examine whether performance in Experiment 2 was due to low-level featural differences (such as top-half/bottom-half balance) between typical and reorganized body images or some combination of low-level features, not readily noticeable by adults but perhaps noticeable by infants (i.e., stimulus complexity or region of interest contrast which would be retained in the headless stimuli). If infants’ performance is affected by the absence of the head, then it would indicate that infants’ performance in Experiment 2 was not due to low-level featural differences between typical and reorganized body images. If, however, performance is not affected by the absence of the head, then it is not possible to rule out the possibility that infants in Experiment 2 were responding on the basis of low-level features.

Method

Participants

Thirty 5-month-old infants (mean age = 150 days, SD = 5.14; 17 female) participated in the study. Data from additional infants were excluded for looking at the stimuli for less than 20% of the duration of the study (n = 6) and not looking to all of the areas of interest (n = 1). As in Experiment 2, a sensitivity analysis indicated that the exclusion of data from these infants did not affect the results.2 Infants were recruited in the same manner as in Experiment 2 and a majority of the parents reported their infants’ race as White (80%). The remainder reported their infants’ race as African American (3%), Asian (3%) and Mixed Race (13%), which was representative of the surrounding area.

Stimuli

The stimuli used were the same as those used in Experiments 1 and 2, except that the head portion of the body images was removed (Figure 3). This allowed for the same low-level features that were present in the first two experiments to also be present here, thereby serving as a control condition.

Figure 3.

Figure 3.

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Examples of the headless typical (A) and headless reorganized (B) stimuli used in Experiment 3. Each infant saw a headless typical image four times and a headless reorganized image four times for a total of eight 12s test trials. Infants viewed one of the possible six headless typical-reorganized body pairs. The AOIs were identical to those pictured in Figure 1.

Apparatus and Procedure

The study utilized the same apparatus and procedure used in Experiment 2.

Results and Discussion

The results were analyzed the same way as in Experiment 2. An outlier analysis (Tukey, 1977; using SPSS version 29.0) revealed that two infants in the headless condition had scores that were outliers. Their scores were greater than 1.5 times the interquartile range above the 75th quartile. Thus, these scores were not included in the following analysis.

When comparing these results to those of the 5-month-olds in Experiment 2, an ANOVA with joint AOIs (typical and reorganized) as within-subjects factors and Condition (with head and headless) as a between-subjects factor was conducted. There was a main effect of Condition such that infants fixated longer on the headless stimuli than on the whole body stimuli F(1,56) = 7.068, p = .010, ηp2 = .112, but this effect was qualified by a significant AOI X Condition interaction, F(1,56) = 4.818, p = .032, ηp2 = .079. This interaction indicates that the distribution of attention to the joint areas for typical versus reorganized bodies differs systematically by the presence versus the absence of the head. The main effect of joint AOIs was not significant. A paired samples t-test failed to reveal a significant difference in looking to the joint AOIs on the typical body (M = 10.70%, SD = 8.75) versus the reorganized body (M = 8.87%, SD = 7.20); t(27) = 1.04, p = .306, d = .23 (Figure 2). Thus, the 5-month-olds in the current experiment did not exhibit differential scanning of reorganized locations of the headless body images.

The results from the current study suggest that the findings from Experiment 2 were not due to low-level features drawing the infants’ attention to the joint regions. If infants were just responding to some low-level features such as top-half/bottom-half balance, then they should have responded in a similar manner in Experiment 3 as in Experiment 2 because all of the differences between the typical and reorganized body images were maintained in the current experiment. However, the fact that infants failed to exhibit differential scanning patterns to the joint regions on the typical versus reorganized images in the headless condition suggests that infants in Experiment 2 were not relying on such low-level features; rather, they were likely responding on the basis of their knowledge of the configuration of the human body.

It is also possible that the lack of an effect in the current study is due to the novel nature of the images. For instance, infants may no longer process the image as a body if there is no head present. Future research should examine the role of the head in infants’ processing of body configurations, especially given that adults’ ability to process body information is impacted when the head is removed (Yovel et al., 2010).

General Discussion

The current study documented the way in which adults and infants attend to specific regions of body reorganizations. Findings from Experiments 2 and 3 allowed us to assess the nature and timing of body knowledge development in infancy by capturing the way in which infants allocate their attention to typical versus reorganized body images. Specifically, it was found that adults and 5-month-olds, but not 3.5-month-olds, attend to specific regions of body images that have been reorganized versus ones that are typical. This difference in scanning patterns demonstrates that by 5 months of age, infants are sensitive to the specific locations of body parts (such as arms and legs). This sensitivity indicates adult-like response patterns that are consistent with early expertise in body processing. However, the results also indicated that 3.5-month-olds display less organized scanning patterns, although previous research (Zieber et al., 2015) suggests that 3.5-month-olds discriminate between typical and reorganized body images. This pattern of findings suggests that 3.5-month-olds may be more responsive to changes in the overall gestalt of body images than to the locations of specific body parts.

Additionally, the use of headless images in Experiment 3 served as a control condition to examine whether the difference in scanning patterns found in Experiment 2, in which infants were tested with whole bodies, were simply due to low-level differences between typical versus reorganized body images (e.g., top-half/bottom-half balance) drawing attention to specific areas, rather than due to infants’ knowledge of the structure of bodies. Because the stimuli remained identical in Experiments 2 and 3 except for the presence/absence of the head, if infants were responding to low-level featural differences between typical and reorganized body images, then the same pattern of results would have been expected in Experiment 3 as in Experiment 2. However, infants failed to exhibit differential scanning patterns in Experiment 3 when the heads were removed. This finding indicates that performance in Experiment 2 was likely due to infants’ sensitivity to the structure of the human body, rather than a response to some low-level featural differences between typical and reorganized body images.

The finding that infants display adult-like response patterns by 5 months of age is consistent with the growing body of work indicating that body representation develops quite early in life. Bhatt et al. (2016) posit that knowledge of bodies develops through a general social cognition system that gives infants the ability to process critical social information from a variety of sources, like faces and bodies. They also suggested an alternative possibility, namely that, rather than a fully integrated social cognition system, early acquisition of body knowledge could emerge through a body-specific knowledge system that benefits from relevant information from the rapidly developing face-processing system. That is, infants’ knowledge of faces could in turn facilitate their knowledge of bodies because of the close association between faces and bodies. Bhatt et al. (2016) suggest that, whether or not a general social cognition system or separate face and body processing systems are prevalent during early development, face and body knowledge development follow similar trajectories. The current findings are consistent with this theory because they indicate that infants are sensitive to the structure of bodies and the locations of specific body parts by 5 months of age. However, the proposals put forth by Bhatt et al. (2016) are not detailed enough to explain why 3.5-month-olds fail to exhibit sensitivity to locations of specific body parts while 5-month-olds do.

The results of the current study are also in agreement with the “like-me” theory (Marshall & Meltzoff, 2015; Meltzoff, 2011) which assumes that body knowledge could be innate or develop early in life due to observation and imitation. According to this theory, 5-month-olds’ sensitivity to detailed body structure information in the current study could be explained by the assumption that, by this age, observation and imitation enables infants’ knowledge about the specific location of certain body parts. However, the fact 3.5-month-olds failed to exhibit sensitivity to specific locations of body parts indicates the necessity for a more detailed and comprehensive theory of when and how knowledge of specific aspects of bodies develops as the pattern of results in this study does not fit within existing theories.

Regardless of why 3.5-month-olds failed, the fact that 5-month-old infants exhibited differential scanning patterns to typical versus reorganized bodies indicates an adult-like approach to seeking information about the human body that aligns with the notion that there is a general social cognition system that could benefit from a system of viewing others as being “like-me” (Bhatt et al., 2016; Marshall & Meltzoff, 2015; Meltzoff, 2011). This is a more parsimonious understanding of body knowledge development rather than the idea of there being a separate body processing system (Slaughter & Heron, 2004; Slaughter, et al., 2012). The latter approach is exemplified by the claim by Slaughter and colleagues (2012) that accurate detection of human bodies gradually occurs over the first 18 months of life and that body detection in static, two-dimensional images in seen only by15–18 months of age. However, findings from the current study suggest that infants’ sensitivity to body configuration is available at least by 5 months, so it is unlikely that body knowledge is purely experience based and develops later in life.

It is important to note that, although Experiment 2 failed to find evidence of 3.5-month-olds sensitivity to specific locations of body parts, it is possible that other dependent measures, such as duration of the longest look, might indicate sensitivity even at this age. For instance, infants could be aware of the exact location of body parts by 3.5 months of age but lack the motivation to exhibit such knowledge as a difference in “spontaneous” scanning patterns. Also, when infants this age exhibited overall preferences between typical and reorganized body images in Zieber et al. (2015), they were tested with the two types of bodies presented side-by-side. In contrast, infants in the current experiments saw only one type of image (typical or reorganized) at a time on the screen. It is possible that young infants need to be able to compare these two types of images side-by-side in order to exhibit sensitivity to the specific differences between them3. Future studies could address this issue by simultaneously presenting 3.5-month-old infants with both a reorganized and a typical body configuration to see if the viewing patterns differ when they can directly compare the two image types. If the results were to show that infants at 3.5 months of age now exhibit differential scanning patterns to the joint regions of the two image types, then it would provide evidence that knowledge about the precise location of body parts emerges as early as 3.5 months.

Taken together, the results from Zieber et al. (2015) and the 3.5-month-olds in the current study shed light on the type of processing necessary to show a spontaneous preference for a stimulus as a whole (global processing of overall gestalt) versus heightened attention to discrete regions within a stimulus (local processing of individual features). Several studies have documented a preference for global information in young infants (e.g., Frick, Colombo, & Allen, 2000; Ghim & Eimas, 1988; but see Westerman & Mareschal, 2004; Younger & Cohen, 1986). Thus, it is possible that without a typical body to serve as a reference, infants’ sensitivity to body configuration is not robust enough to isolate and attend to specific areas of reorganization until 5 months of age.

It is also possible that the use of static images in the current study made it more difficult for infants at 3.5 months of age to identify differences in the two images which resulted in a lack of looking to the joint regions on the reorganized images. It would be beneficial for future studies to include the use of dynamic stimuli where the joint regions are in motion to highlight the reorganization. Such studies would document the way in which movement impacts younger infants’ knowledge of body structure.

Recall that infants in the current experiments were tested only on female stimuli. Future research should examine whether similar results would be obtained if they were tested on male stimuli. Research indicates that infants perform better on female faces than on male faces in a variety of tasks if they have a primary female caregiver (Quinn, et al., 2002; Ramsey et al., 2005; Ramsey-Rennels & Langlois, 2006). These findings demonstrate the role of experience on the development of facial knowledge. If infants’ primary caregivers are female, and prior experience with a particular gender impacts their knowledge of the structure of a human body, then it would be expected that infants would no longer exhibit differential scanning patterns when presented with male stimuli. Such an outcome would suggest that experience plays a role in the development of knowledge about bodies in infancy. However, previous studies have also demonstrated that infants show specialized scanning patterns to both male and female bodies (White et al., 2018; White et al., 2019). Therefore, exposure to males may not be as crucial when it comes to body structure knowledge early in life due to the fact that the global body structure remains the same for males and females. Future research should examine this question to determine the role that experience plays in infants’ body structure knowledge.

Overall, the findings from the current study add to the existing literature on infant cognition and body knowledge development. By 5 months of age, infants’ knowledge of bodies includes knowledge about the specific location of the parts that make up the body. In this respect, 5-month-olds’ body representation resembled that of adults in Experiment 1. It is possible that infants younger than 5 months are also sensitive to the precise locations of body parts, but that was not evident in the current study. It could be the case that infants’ sensitivity to structural information arises from their increasing knowledge about their own bodies (de Klerk et al., 2021). This is a possibility that should be examined by future work.

The developmental change documented in the current research is akin to other instances of developmental change in cognition (e.g., Bhatt et al., 2005) within the first year of life. Bhatt et al. (2005) documented a developmental change in face processing abilities in which 5-month-olds, but not 3-month-olds, were sensitive to subtle spatial information (like the space between the eyes) in faces, thus suggesting the later development of at least one face processing mechanism. Such developmental changes indicate that social cognition develops between 3.5 and 5 months of age and the developmental change documented in the current study in which 5-month-olds, but not 3.5-month-olds, exhibited sensitivity to specific locations of body parts is another manifestation of such a change.

In conclusion, there were multiple findings of interest in the current study. First, adults’ attention to areas of reorganization were documented in order to better understand their scanning patterns to bodies that were typical versus reorganized. Second, it was found that 5-month-olds, but not 3.5-month-olds, exhibit adult-like differential scanning patterns to the specific areas of manipulation on images of reorganized versus typically configured bodies. This finding suggests that infants by 5 months of age are able to discern when body parts are not in their canonical locations and attend specifically to locations of reorganization, indicating a fairly sophisticated representation of body structure and part locations.

Acknowledgments

The authors declare no conflicts of interest with regard to the funding source for this study. The data that support the findings of this study are available from the corresponding author upon reasonable request. This research was supported by a grant from the National Institute of Child Health and Human Development (HD075829). The authors would like to thank the infants and parents who participated in this study.

Footnotes

1

An outlier analysis (Tukey, 1977; using SPSS version 29.0) with the data of all infants with >10% looking included revealed that three of the infants had scores that were greater than 1.5 times the interquartile range above the 75th quartile. Thus, these scores were not included in the analysis. A paired samples t-test revealed that the 5-month-olds looked proportionally less at the joint AOIs on the typical body (M = 4.9%, SD = 3.63) than on the reorganized body (M = 7.2%, SD = 5.60); t(32) = −2.30, p = .028.

2

An outlier analysis (Tukey, 1977; using SPSS version 29.0) of data from all infants with >10% looking revealed that two of the infants had scores that were greater than 1.5 times the interquartile range above the 75th quartile. Thus, these scores were not included in the following analysis. A paired samples t-test failed to reveal a significant difference in percent looking to the joint AOIs on the typical body (M = 10.54%, SD = 8.64) versus on the reorganized body (M = 9.25%, SD = 7.37); t(29) = 0.724, p = .475.

3

In an effort to compare our data to that of Zieber and colleagues (2015), a paired-samples t-test revealed that the 3.5-month-olds exhibited no difference in percent total fixation duration to the overall stimulus AOI of the typical body (M = 25.54%, SD = 23.13) versus the reorganized body (M = 24.65%, SD = 19.90), t(29) = .661, p = .514, d = .12. This is unsurprising given that the images in the current study were presented sequentially rather than side by side.

References

  1. Atkinson J, Hood B, Wattam-Bell J, & Braddick O (1992). Changes in infants’ ability to switch visual attention in the first three months of life. Perception, 21(5), 643–653. [DOI] [PubMed] [Google Scholar]
  2. Aviezer H, Trope Y, & Todorov A (2012). Body cues, not facial expressions, discriminate between intense positive and negative emotions. Science, 338(6111), 1225–1229. [DOI] [PubMed] [Google Scholar]
  3. Bhatt RS, Bertin E, Hayden A, & Reed A (2005). Face processing in infancy: Developmental changes in the use of different kinds of relational information. Child Development, 76(1), 169–181. [DOI] [PubMed] [Google Scholar]
  4. Bhatt RS, Hock A, White H, Jubran R, & Galati A (2016). The development of body structure knowledge in infancy. Child Development Perspectives, 10, 45–52. [DOI] [PMC free article] [PubMed] [Google Scholar]
  5. Bronson GW (1994). Infants’ transitions toward adult-like scanning. Child Development, 65(5), 1243–1261. [DOI] [PubMed] [Google Scholar]
  6. Carey S (1992). Becoming a face expert. Philosophical Transactions of the Royal Society of London, Series B: Biological Sciences, 335, 95–102. [DOI] [PubMed] [Google Scholar]
  7. Damm SA, Sis JL, Kulkarni AM, & Chatterjee M (2019). How vocal emotions produced by children with cochlear implants are perceived by their hearing peers. Journal of Speech, Language, and Hearing Research, 62(10), 3728–3740. [DOI] [PMC free article] [PubMed] [Google Scholar]
  8. DeGutis J, Cohan S, & Nakayama K (2014). Holistic face training enhances face processing in developmental prosopagnosia. Brain, 137(6), 1781–1798. [DOI] [PMC free article] [PubMed] [Google Scholar]
  9. de Klerk CC, Filippetti ML, & Rigato S (2021). The development of body representations: An associative learning account. Proceedings of the Royal Society B, 288(1949), 1–10. [DOI] [PMC free article] [PubMed] [Google Scholar]
  10. Diamond R, & Carey S (1986). Why faces are and are not special: An effect of expertise. Journal of Experimental Psychology: General, 115(2), 107–117. [DOI] [PubMed] [Google Scholar]
  11. Doyle FL, Klein L, Kemp LJ, Moul C, Richmond JL, Eapen V, Frick PJ, Kimonis ER, Hawes DJ, Le Pelley ME, Mehta D, & Dadds MR (2022). Learning to like triangles: A longitudinal investigation of evaluative conditioning in infancy. Developmental Psychobiology, 64(3), e22244. [DOI] [PubMed] [Google Scholar]
  12. Fast J (1988). Body language. New York, NY: Simon and Schuster. [Google Scholar]
  13. Frick JE, Colombo J, & Allen JR (2000). Temporal sequence of global-local processing in 3-month-old infants. Infancy, 1(3), 375–386. [DOI] [PubMed] [Google Scholar]
  14. Ghim HR, & Eimas PD (1988). Global and local processing by 3-and 4-month-old infants. Perception & Psychophysics, 43(2), 165–171. [DOI] [PubMed] [Google Scholar]
  15. Gliga T, & Dehaene-Lambertz G (2005). Structural encoding of body and face in human infants and adults. Journal of Cognitive Neuroscience, 17(8), 1328–1340. [DOI] [PubMed] [Google Scholar]
  16. Gupta N, White H, Trott S, & Spiegel JH (2022). Observer gaze patterns of patient photographs before and after facial feminization. Aesthetic Surgery Journal, 42(7), 725–732. [DOI] [PubMed] [Google Scholar]
  17. Heck A, Chroust A, White H, Jubran R, & Bhatt RS (2018). Development of body emotion perception in infancy: From discrimination to recognition. Infant Behavior and Development, 50, 42–51. [DOI] [PMC free article] [PubMed] [Google Scholar]
  18. Hewig J, Trippe RH, Hecht H, Straube T, & Miltner WH (2008). Gender differences for specific body regions when looking at men and women. Journal of Nonverbal Behavior, 32(2), 67–78. [Google Scholar]
  19. Hock A, Kangas A, Zieber N, & Bhatt RS (2015). The development of sex category representation in infancy: Matching of faces and bodies. Developmental Psychology, 51(3), 346–352. [DOI] [PMC free article] [PubMed] [Google Scholar]
  20. Hock A, White H, Jubran R, & Bhatt RS (2016). The whole picture: Holistic body posture recognition in infancy. Psychonomic Bulletin & Review, 23(2), 426–431. [DOI] [PMC free article] [PubMed] [Google Scholar]
  21. Hunnius S, de Wit TC, Vrins S, & von Hofsten C (2011). Facing threat: Infants’ and adults’ visual scanning of faces with neutral, happy, sad, angry, and fearful emotional expressions. Cognition & Emotion, 25, 193–205. [DOI] [PubMed] [Google Scholar]
  22. Kanwisher N, McDermott J, & Chun MM (1997). The fusiform face area: A module in human extrastriate cortex specialized for face perception. Journal of Neuroscience, 17(11), 4302–4311. [DOI] [PMC free article] [PubMed] [Google Scholar]
  23. Kirkham NZ, Slemmer JA, & Johnson SP (2002). Visual statistical learning in infancy: Evidence for a domain general learning mechanism. Cognition, 83(2), B35–B42. [DOI] [PubMed] [Google Scholar]
  24. Kovack-Lesh KA, McMurray B, & Oakes LM (2014). Four-month-old infants’ visual investigation of cats and dogs: Relations with pet experience and attentional strategy. Developmental Psychology, 50(2), 402. [DOI] [PubMed] [Google Scholar]
  25. Kret ME, Stekelenburg JJ, Roelofs K, & de Gelder B (2013). Perception of face and body expressions using electromyography, pupillometry and gaze measures. Frontiers in Psychology, 4, 177–188. [DOI] [PMC free article] [PubMed] [Google Scholar]
  26. Marshall PJ, & Meltzoff AN (2015). Body maps in the infant brain. Trends in Cognitive Sciences, 19(9), 499–505. [DOI] [PMC free article] [PubMed] [Google Scholar]
  27. Maurer D, Le Grand RL, & Mondloch CJ (2002). The many faces of configural processing. Trends in Cognitive Sciences, 6(6), 255–260. [DOI] [PubMed] [Google Scholar]
  28. Meltzoff AN (2011). Social cognition and the origins of imitation, empathy, and theory of mind. The Wiley-Blackwell Handbook of Childhood Cognitive Development, 1, 49–75. [Google Scholar]
  29. Meltzoff AN, & Moore MK (1997). Explaining facial imitation: A theoretical model. Early Development & Parenting, 6(3–4), 179. [DOI] [PMC free article] [PubMed] [Google Scholar]
  30. Meltzoff AN, Murray L, Simpson E, Heimann M, Nagy E, Nadel J, Pedersen EJ, Brooks R, Messinger DS, De Pascalis L, Subiaul F, Paukner A, & Ferrari PF (2018a). Eliciting imitation in early infancy. Developmental Science, 22(2), 1–3. [DOI] [PMC free article] [PubMed] [Google Scholar]
  31. Meltzoff AN, Ramírez RR, Saby JN, Larson E, Taulu S, & Marshall PJ (2018b). Infant brain responses to felt and observed touch of hands and feet: An MEG study. Developmental Science 21(5). 1–13. 10.1111/desc.12651 [DOI] [PMC free article] [PubMed] [Google Scholar]
  32. Morita T, Slaughter V, Katayama N, Kitazaki M, Kakigi R, & Itakura S (2012). Infant and adult perceptions of possible and impossible body movements: An eye-tracking study. Journal of Experimental Child Psychology, 113(3), 401–414. [DOI] [PubMed] [Google Scholar]
  33. Morton J, & Johnson MH (1991). CONSPEC and CONLERN: A two-process theory of infant face recognition. Psychological Review, 98(2), 164–181. [DOI] [PubMed] [Google Scholar]
  34. Nummenmaa L, Hietanen JK, Santtila P, & Hyönä J (2012). Gender and visibility of sexual cues influence eye movements while viewing faces and bodies. Archives of Sexual Behavior, 41(6), 1439–1451. [DOI] [PubMed] [Google Scholar]
  35. Olsen A (2012). The Tobii I-VT fixation filter. Tobii Technology, 21, 4–19. [Google Scholar]
  36. Papageorgiou KA, Smith TJ, Wu R, Johnson MH, Kirkham NZ, & Ronald A (2014). Individual differences in infant fixation duration relate to attention and behavioral control in childhood. Psychological Science, 25, 1371–1379. [DOI] [PubMed] [Google Scholar]
  37. Quinn PC, Lee K, & Pascalis O (2019). Face processing in infancy and beyond: The case of social categories. Annual Review of Psychology, 70, 165–189. [DOI] [PubMed] [Google Scholar]
  38. Quinn PC, Yahr J, Kuhn A, Slater AM, & Pascalis O (2002). Representation of the gender of human faces by infants: A preference for female. Perception, 31(9), 1109–1121. [DOI] [PubMed] [Google Scholar]
  39. Ramsey JL, Langlois JH, & Marti NC (2005). Infant categorization of faces: Ladies first. Developmental Review, 25(2), 212–246. [Google Scholar]
  40. Ramsey-Rennels JL, & Langlois JH (2006). Infants’ differential processing of female and male faces. Current Directions in Psychological Science, 15(2), 59–62. [Google Scholar]
  41. Reed CL, Stone VE, Bozova S, & Tanaka J (2003). The body inversion effect. Psychological Science, 14, 302–308. [DOI] [PubMed] [Google Scholar]
  42. Reed CL, Stone VE, Grubb JD, & McGoldrick JE (2006). Turning configural processing upside down: Part and whole body postures. Journal of Experimental Psychology-Human Perception and Performance, 32(1), 73–86. [DOI] [PubMed] [Google Scholar]
  43. Rice LM, Wall CA, Fogel A, & Shic F (2015). Computer-assisted face processing instruction improves emotion recognition, mentalizing, and social skills in students with ASD. Journal of Autism and Developmental Disorders, 45, 2176–2186. [DOI] [PubMed] [Google Scholar]
  44. Saffran JR, Aslin RN, & Newport EL (1996). Statistical learning by 8-month-old infants. Science, 274(5294), 1926–1928. [DOI] [PubMed] [Google Scholar]
  45. Saint SE, Hammond BR Jr, O’Brien KJ, & Frick JE (2017). Developmental trends in infant temporal processing speed. Vision Research, 138, 71–77. [DOI] [PubMed] [Google Scholar]
  46. Slaughter V, & Heron M (2004). Origins and early development of human body knowledge. Monographs of the Society for Research in Child Development, 69, 1–102. [DOI] [PubMed] [Google Scholar]
  47. Slaughter V, Heron-Delaney M, & Christie T (2012). Developing expertise in human body perception. In Slaughter V & Brownell C (Eds.), Early development of body representations (pp. 81–100). Cambridge: Cambridge University Press. [Google Scholar]
  48. Tukey JW (1977). Exploratory data analysis. Reading, MA: Addison-Wesley. [Google Scholar]
  49. Westermann G, & Mareschal D (2004). From parts to wholes: Mechanisms of development in infant visual object processing. Infancy, 5(2), 131–151. [DOI] [PubMed] [Google Scholar]
  50. White H, Hock A, Jubran R, Heck A, & Bhatt RS (2018). Visual scanning of male and female bodies in infancy. Journal of Experimental Child Psychology, 166, 79–95. [DOI] [PMC free article] [PubMed] [Google Scholar]
  51. White H, Jubran R, Heck A, Chroust A, & Bhatt RS (2019). Sex-specific scanning in infancy: Developmental changes in the use of face/head and body information. Journal of Experimental Child Psychology, 182, 126–143. [DOI] [PMC free article] [PubMed] [Google Scholar]
  52. White H, Heck A, Jubran R, Chroust A, & Bhatt RS (2022). Average fixation duration in infancy: Stability and predictive utility. Infancy, 27(5), 866–886. [DOI] [PubMed] [Google Scholar]
  53. Xiao WS, Quinn PC, Pascalis O, & Lee K (2014). Own- and other-race face scanning in infants: Implications for perceptual narrowing. Developmental Psychobiology, 56, 262–273. [DOI] [PubMed] [Google Scholar]
  54. Younger BA, & Cohen LB (1986). Developmental change in infants’ perception of correlations among attributes. Child Development, 803–815. [PubMed] [Google Scholar]
  55. Yovel G, Pelc T, & Lubetzky I (2010). It’s all in your head: Why is the body inversion effect abolished for headless bodies? Journal of Experimental Psychology: Human Perception and Performance, 36(3), 759. [DOI] [PubMed] [Google Scholar]
  56. Zieber N, Kangas A, Hock A, & Bhatt RS (2014). Infants’ perception of emotion from body movements. Child Development, 85(2), 675–684. [DOI] [PubMed] [Google Scholar]
  57. Zieber N, Kangas A, Hock A, & Bhatt RS (2015). Body structure perception in infancy. Infancy, 20(1), 1–17. [Google Scholar]

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