Validation of an open source, remote web-based eye-tracking method (WebGazer) for research in early childhood.

Measuring eye movements remotely via the participant's webcam promises to be an attractive methodological addition to in-person eye-tracking in the lab. However, there is a lack of systematic research comparing remote web-based eye-tracking with in-lab eye-tracking in young children. We report a multi-lab study that compared these two measures in an anticipatory looking task with toddlers using WebGazer.js and jsPsych. Results of our remotely tested sample of 18-27-month-old toddlers (N = 125) revealed that web-based eye-tracking successfully captured goal-based action predictions, although the proportion of the goal-directed anticipatory looking was lower compared to the in-lab sample (N = 70). As expected, attrition rate was substantially higher in the web-based (42%) than the in-lab sample (10%). Excluding trials based on visual inspection of the match of time-locked gaze coordinates and the participant's webcam video overlayed on the stimuli was an important preprocessing step to reduce noise in the data. We discuss the use of this remote web-based method in comparison with other current methodological innovations. Our study demonstrates that remote web-based eye-tracking can be a useful tool for testing toddlers, facilitating recruitment of larger and more diverse samples; a caveat to consider is the larger drop-out rate.

Infants' Preference for Social Interactions Increases from 7 to 13 Months of Age.

This study examined 7-to-13.5-month-old middle-class Western infants' visual orienting to third-party interactions in parallel with their social attention behavior during own social interactions (Leipzig, Germany). In Experiment 1, 9.5- to-11-month-olds (n = 20) looked longer than 7- to-8.5-month-olds (n = 20) at videos showing two adults interacting with one another when simultaneously presented with a scene showing two adults acting individually. Moreover, older infants showed higher social engagement (including joint attention) during parent-infant free play. Experiment 2 replicated this age-related increase in both measures and showed that it follows continuous trajectories from 7 to 13.5 months (n = 50). This suggests that infants' attentional orienting to others' interactions coincides with parallel developments in their social attention behavior during own social interactions.

Social interaction targets enhance 13-month-old infants' associative learning.

Infants are attentive to third-party interactions, but the underlying mechanisms of this preference remain understudied. This study examined whether 13-month-old infants (N = 32) selectively learn cue-target associations guiding them to videos depicting a social interaction scene. In a visual learning task, two geometrical shapes were repeatedly paired with two kinds of target videos: two adults interacting with one another (social interaction) or the same adults acting individually (non-interactive control). Infants performed faster saccadic latencies and more predictive gaze shifts toward the cued target region during social interaction trials. These findings suggest that social interaction targets can serve as primary reinforcers in an associative learning task, supporting the view that infants find it intrinsically valuable to observe others' interactions.

Direct and Observed Joint Attention Modulate 9-Month-Old Infants' Object Encoding.

Sharing joint visual attention to an object with another person biases infants to encode qualitatively different object properties compared to a parallel attention situation lacking interpersonal sharedness. This study investigated whether merely observing joint attention amongst others shows the same effect. In Experiment 1 (first-party replication experiment), N = 36 9-month-old German infants were presented with a violation-of-expectation task during which they saw an adult looking either in the direction of the infant (eye contact) or to the side (no eye contact) before and after looking at an object. Following an occlusion phase, infants saw one of three different outcomes: the same object reappeared at the same screen position (no change), the same object reappeared at a novel position (location change), or a novel object appeared at the same position (identity change). We found that infants looked longer at identity change outcomes (vs. no changes) in the "eye contact" condition compared to the "no eye contact" condition. In contrast, infants' response to location changes was not influenced by the presence of eye contact. In Experiment 2, we found the same result pattern in a matched third-party design, in which another sample of N = 36 9-month-old German infants saw two adults establishing eye contact (or no eye contact) before alternating their gaze between an object and their partner without ever looking at the infant. These findings indicate that infants learn similarly from interacting with others and observing others interact, suggesting that infant cultural learning extends beyond infant-directed interactions.

Processing third-party social interactions in the human infant brain.

The understanding of developing social brain functions during infancy relies on research that has focused on studying how infants engage in first-person social interactions or view individual agents and their actions. Behavioral research suggests that observing and learning from third-party social interactions plays a foundational role in early social and moral development. However, the brain systems involved in observing third-party social interactions during infancy are unknown. The current study tested the hypothesis that brain systems in prefrontal and temporal cortex, previously identified in adults and children, begin to specialize in third-party social interaction processing during infancy. Infants (N = 62), ranging from 6 to 13 months in age, had their brain responses measured using functional near-infrared spectroscopy (fNIRS) while viewing third-party social interactions and two control conditions, infants viewing two individual actions and infants viewing inverted social interactions. The results show that infants preferentially engage brain regions localized within the dorsomedial prefrontal cortex when viewing third-party social interactions. These findings suggest that brain systems processing third-party social interaction begin to develop early in human ontogeny and may thus play a foundational role in supporting the interpretation of and learning from social interactions.

Observing others' joint attention increases 9-month-old infants' object encoding.

In direct interactions with others, 9-month-old infants' learning about objects is facilitated when the interaction partner addresses the infant through eye contact before looking toward an object. In this study we investigated whether similar factors promote infants' observational learning from third-party interactions. In Experiment 1, 9-month-old typically developing infants from mixed socioeconomic backgrounds from urban Germany (N = 32, 13 female) were presented with four types of videos showing one object and two adults. The scenarios varied systematically regarding the eye contact between the adults (eye contact or no eye contact), and the adults' object-directed gaze (looking toward or away from the object). To assess infants' encoding performance we measured their looking times when seeing the familiarized object subsequently next to a novel object, interpreting an enhanced novelty preference as reversely indicating greater encoding of the familiarized object. Infants showed an increased novelty preference, but only after observing a joint attentional setting during which two adults attended to the familiarized object together (following eye contact). In Experiment 2, we found an identical pattern of results in a matched first-party design in which 9-month-old infants (N = 32, 16 female) were directly addressed by one single adult on screen. Infants' encoding was only enhanced when the adult made eye contact with the infant before looking at an object. Together, this suggests that the capacity to learn through observing others' interactions emerges already in the first postnatal year, and that it may depend on similar factors as infants' learning through direct social engagement. (PsycInfo Database Record (c) 2021 APA, all rights reserved).