Pupillometry reveals communication‐induced object expectations in 12‐ but not 8‐month‐old infants

Out of sight, not out of mind: New pupillometric evidence on object permanence in a sample of 10- and 12-month-old German infants

Findings on the emergence and interpretation of early object representation in the first year of life diverge widely between designs that employ looking times versus action-based measures. As a promising new approach, pupillometry has produced evidence for object permanence at 18 months of age, but not younger as of yet. In the current study, we (re)investigated object permanence following occlusion events in a pupillometric violation-of-expectation paradigm optimized for younger infants. During each trial, infants observed a toy object's occlusion and prompt reveal in the expected condition or its absence in the unexpected condition. Across two experiments, we show that 10- and 12-month-old infants' (total N = 82) pupils dilate in response to unexpected object disappearances relative to expected appearances. Control analyses revealed no differences between the scenes before the experimental manipulation, excluding perceptual interpretations. We further report an age-dependent effect of condition on pupil responses, with unexpected outcomes triggering greater pupil dilation in the older group. These results provide positive pupillometric evidence in support of object permanence in the context of a violation-of-expectation paradigm at 10 and 12 months of age.

14-month-old infants detect a semantic mismatch when occluded objects are mislabeled

When infants start mastering their first language, they may start to notice when words are used incorrectly. Around 14-months of age, infants detect incorrect labeling when they are presented with an object which is labeled while still visible. However, things that are referred to are often out of sight when we communicate about them. The present study examined infants' detection of semantic mismatch when the object was occluded at the time of labeling. Specifically, we investigated whether mislabeling that referred to an occluded object could elicit a semantic mismatch. We showed 14-month-old Danish-speaking infants events where an onscreen agent showed an object and then hid it in a box. This was followed by another agent's hand pointing at the box, and a concurrent auditory category label played, which either matched or did not match the hidden object. Our results indicate that there is an effect of semantic mismatch with a larger negativity in incongruent trials. Thus, infants detected a mismatch, as indicated by a larger n400, when occluded objects were mislabeled. This finding suggests that infants can sustain an object representation in memory and compare it to a semantic representation of an auditory category label.

Applicability and usefulness of pupillometry in the study of lexical access. A scoping review of primary research

Pupil dilation has been associated with the effort required to perform various cognitive tasks. At the lexical level, some studies suggest that this neurophysiological measure would provide objective, real-time information during word processing and lexical access. However, due to the scarcity and incipient advancement of this line of research, its applicability, use, and sensitivity are not entirely clear. This scoping review aims to determine the applicability and usefulness of pupillometry in the study of lexical access by providing an up-to-date overview of research in this area. Following the PRISMA protocol, 16 articles were included in this review. The results show that pupillometry is a highly applicable, useful, and sensitive method for assessing lexical skills of word recognition, word retrieval, and semantic activation. Moreover, it easily fits into traditional research paradigms and methods in the field. Because it is a non-invasive, objective, and automated procedure, it can be applied to any population or age group. However, the emerging development of this specific area of research and the methodological diversity observed in the included studies do not yet allow for definitive conclusions in this area, which in turn does not allow for meta-analyses or fully conclusive statements about what the pupil response actually reflects when processing words. Standardized pupillary recording and analysis methods need to be defined to generate more accurate, replicable research designs with more reliable results to strengthen this line of research.

Preverbal infants' understanding of social norms

Social norms are foundational to human cooperation and co-existence in social groups. A crucial marker of social norms is that a behavior is not only shared, but that the conformity to the behavior of others is a basis for social evaluation (i.e., reinforcement and sanctioning), taking the is, how individuals usually behave, to an ought, how individuals should behave to be socially approved by others. In this preregistered study, we show that 11-month-old infants grasp this fundamental aspect about social norms already in their first year. They showed a pupillary surprise response for unexpected social responses, namely the disapproval and exclusion of an individual who showed the same behavior like others or the approval and inclusion of an individual who behaved differently. That preverbal infants link the conformity with others' behavior to social evaluations, before they respond to norm violations themselves, indicates that the foundations of social norm understanding lie in early infancy.

Correlates of infant pointing frequency in the first year

This study examines the emergence of concurrent correlates of infant pointing frequency with the aim of contributing to its ontogenetic theories. We measured monthly from 8 to 12 months infants' (N = 56) index-finger pointing frequency along with several candidate correlates: (1) family socioeconomic status (SES), (2) mothers' pointing production, and (3) infants' point following to targets in front of and behind them. Results revealed that (1) infants increased their pointing frequency across age, but high-SES infants had a steeper increase, and a higher pointing frequency than low-SES infants from 10 months onward, (2) maternal pointing frequency was not associated with infant pointing frequency at any age, (3) infants' point following abilities to targets behind their visual fields was positively associated with their pointing frequency at 12 months, after pointing had already emerged around 10 months. Findings suggest that family SES impacts infants' pointing development more generally, not just through maternal pointing. The association between pointing and following points to targets behind, but not in front, suggests that a higher level of referential understanding emerges after, and perhaps through the production of pointing.

Emerging Self-Representation Presents a Challenge When Perspectives Conflict

The capacity to take another's perspective appears to be present from early in life, with young infants ostensibly able to predict others' behaviour even when the self and other perspective are at odds. Yet, infants' abilities are difficult to reconcile with the well-known problems that older children have with ignoring their own perspective. Here we show that it is the development of the self-perspective, at around 18 months, that creates a perspective conflict between self and other during a non-verbal perspective-tracking scenario. Using mirror self-recognition as a measure of self-awareness and pupil dilation to index conflict processing, our results show that mirror recognisers perceive greater conflict during action anticipation, specifically in a high inhibitory demand condition, in which conflict between self and other should be particularly salient.

Nonverbal Action Interpretation Guides Novel Word Disambiguation in 12-Month-Olds

Whether young infants can exploit sociopragmatic information to interpret new words is a matter of debate. Based on findings and theories from the action interpretation literature, we hypothesized that 12-month-olds should distinguish communicative object-directed actions expressing reference from instrumental object-directed actions indicative of one's goals, and selectively use the former to identify referents of novel linguistic expressions. This hypothesis was tested across four eye-tracking experiments. Infants watched pairs of unfamiliar objects, one of which was first targeted by either a communicative action (e.g., pointing) or an instrumental action (e.g., grasping) and then labeled with a novel word. As predicted, infants fast-mapped the novel words onto the targeted objects after pointing (Experiments 1 and 4) but not after grasping (Experiment 2) unless the grasping action was preceded by an ostensive signal (Experiment 3). Moreover, whenever infants mapped a novel word onto the object indicated by a communicative action, they tended to map a different novel word onto the distractor object, displaying a mutual exclusivity effect. This reliance on nonverbal action interpretation in the disambiguation of novel words indicates that sociopragmatic inferences about reference likely supplement associative and statistical learning mechanisms from the outset of word learning.

Inferring hidden objects from still and communicative onlookers at 8, 14, and 36 months of age

The current study investigated across five eye-tracking experiments children's developing skill of adopting others' referential perspective (Level 1 perspective taking) and to what extent it involves automatic processes or requires ostensive communicative cues. Three age groups (8-, 14-, and 36-month-olds) were tested on their expectation of an object appearing behind one of two peripheral occluders. A centrally presented person in profile either provided an ostensive communicative pointing cue or sat still, oriented to one of the two occluders. The 14-month-olds anticipated the hidden object when the onlooker had communicatively pointed to the location, as revealed by faster target detection in congruent trials (latency effect) and longer dwell times to the empty side in incongruent trials (violation-of-expectation effect). This was not the case when a still person was only oriented to one side. Adding emotional expressions to the still person (Experiment 2) did not help to produce the effects. However, at 36 months of age (Experiment 3), children showed both effects for the still person. The 8-month-olds did not show the violation-of-expectation effect for communicative pointing (Experiment 4) or for a matched abbreviated reach (Experiment 5b), showing it only for a complete reach behind the occluder (Experiment 5a), although they were faster to detect the congruent object in Experiment 4 and 5a. Findings reveal that automatic perspective taking develops after communicative perspective taking and that communicative perspective taking is a developmental outcome of the first year of life. The developmental pattern suggests a continuous social construction process of perspective-taking skills.

Does surprise enhance infant memory? Assessing the impact of the encoding context on subsequent object recognition

A discrepancy between what was predicted and what is observed has been linked to increased looking times, changes in brain electrical activity, and increased pupil dilation in infants. These processes associated with heightened attention and readiness to learn might enhance the encoding and memory consolidation of the surprising object, as suggested by both the infant and the adult literature. We therefore investigated whether the presence of surprise during the encoding context enhances subsequent encoding and recognition memory processes for the items that violated infants' expectations. Seventeen-month-olds viewed 20 familiar objects, half of which were labeled correctly, while the other half were mislabeled. Subsequently, infants were presented with a silent recognition memory test where the previously labeled objects appeared along with new images. Pupil dilation was measured, with more dilated pupils indicating (1) surprise during those labeling events where the item was mislabeled and (2) successful retrieval processes during the memory test. Infants responded with more pupil dilation to mislabeling compared to correct labeling. Importantly, despite the presence of a surprise response during mislabeling, infants only differentiated between the previously seen and unseen items at the memory test, offering no evidence that surprise had facilitated the encoding of the mislabeled items.

Pupillometric VoE paradigm reveals that 18- but not 10-month-olds spontaneously represent occluded objects (but not empty sets)

Object permanence has been investigated with a variety of paradigms and measures, yielding heterogeneous findings. The current study employed a novel Violation-of-Expectation paradigm measuring pupil dilation as indicator of cognitive effort and surprise. Across repeated trials, infants watched videos of animated toys either stopping in an open door frame or moving across the open door frame off screen. The door then closed and opened up again to reveal either the toy, or an empty space. In Experiment 1, 18-month-olds's pupils dilated in response to the unexpected empty outcome more than to the expected empty outcome, establishing the paradigm as a suitable measure of violation of object expectation. Using the same paradigm, Experiment 2 revealed an absence of this object expectation effect for 10-month-olds. Results are discussed with regard to paradigmatic aspects and developmental differences. It is suggested that young infants do not automatically represent occluded objects upon perceiving occlusion events, and that occlusion events may initially require relevance in terms of individual activity or social interaction.