Empty Looks or Paying Attention? Exploring Infants' Visual Behavior during Encoding of an Elicited Imitation Task

Recently, there has been an increased interest in the relationship between looking time during encoding and subsequent memory performance in imitation tasks. Hitherto, the results have been inconclusive: one line of research supporting the link between looking time and performance and another line finding no relation. The existing studies may, however, have been restricted by using small samples, limited looking time measures, and short retention intervals. We here examined the relationship between the encoding process by means of looking time as well as pupil dilation (by means of eye‐tracking technology) in sixty‐eight 20‐month‐old infants participating in an elicited imitation task and their subsequent memory performance (at an encoding test and at a 2‐week delayed recall test). Additional twenty‐two infants provided baseline measures. Simple looking time (assessed as fixation duration) did not correlate consistently with subsequent memory measures. In some cases, however, looking time correlated negatively with imitation scores. In contrast, positive correlations were found between pupil dilation and some of the memory measures, suggesting that pupil dilation may be a more sensitive tool compared to looking time measures.     

Maternal Into‐The‐Face Behavior,Shared Attention,and Infant Distress During Face‐to‐Face Play at 12 Months: Bi‐directional Contingencies

We describe a new maternal intrusion behavior, moving a toy or hand “into‐the‐face” of the infant, and we investigate its bi‐directional associations with infant‐initiated shared attention, infant distress, and infant gaze, during mother–infant face‐to‐face play at 12 months. The play was videotaped split‐screen, with infants seated in a high chair. Videotapes were coded on a 1‐sec time base for mother and infant gaze (at partner, toy, both, or gaze away); infant distress; and maternal intrusion behavior, “into‐the‐face.” We defined “infant‐initiated shared attention” as mother and infant looking in the same second at a toy that the infant‐initiated interest in. We documented that maternal into‐the‐face behavior decreased the likelihood of infant‐initiated shared attention, increased the likelihood of infant distress, and decreased the likelihood of infant gazing away. Reciprocally, infant distress and gazing away increased the likelihood of mother into‐the‐face. In moments when the dyad was engaged in infant‐initiated shared attention, mother into‐the‐face was less likely. This work documents bi‐directional contingencies in the regulation of maternal intrusion and infant behavior during face‐to‐face play at 12 months. We suggest that mother into‐the‐face behavior disturbs an aspect of the infant's experience of recognition.     

Preference for Dynamic Human Images and Gaze‐Following Abilities in Preterm Infants at 6 and 12 Months of Age: An Eye‐Tracking Study

Preterm children are reported to be at higher risk of social communication problems such as autism spectrum disorder compared with full‐term infants. Although previous studies have suggested that preference for social stimuli in infancy is a possible indicator of later social communication development, little is known about this relation in preterm infants. We examined the gaze behavior of low‐risk preterm and full‐term infants at 6 and 12 months' corrected ages using two types of eye‐tracking tasks, which measured 1) preference for social stimuli by biological motion and human geometric preference and 2) ability to follow another's gaze direction. We found that preterm (compared with full‐term) infants at both 6 and 12 months of age spent less time looking toward dynamic human images, followed another's gaze less frequently, and looked for a shorter time at an object cued by another. Moreover, we found a positive correlation between looking time toward dynamic human images and frequency of gaze following at 12 months of age in full‐term, but not preterm, infants. We discuss the relation between the atypical patterns of gaze behavior in preterm infants and their higher risk of later social communication problems.     

Consequences of Eye Color,Positioning, and Head Movement for Eye‐Tracking Data Quality in Infant Research

Eye tracking has become a valuable tool for investigating infant looking behavior over the last decades. However, where eye‐tracking methodology and achieving high data quality have received a much attention for adult participants, it is unclear how these results generalize to infant research. This is particularly important as infants behave different from adults in front of the eye tracker. In this study, we investigated whether eye physiology, positioning, and infant behavior affect measures of eye‐tracking data quality: accuracy, precision, and data loss. We report that accuracy and precision are lower, and more data loss occurs for infants with bluish eye color compared to infants with brownish eye color. Moreover, accuracy was lower for infants positioned in a high chair or in the parents' lap compared to infants positioned in a baby seat. Finally, precision decreased and data loss increased as a function of time. We highlight the importance of data quality when comparing multiple groups, as differences in data quality can affect eye‐tracking measures. In addition, we investigate how two different measures to quantify infant movement influence eye‐tracker data quality. These findings might help researchers with data collection and help manufacturers develop better eye‐tracking systems for infants.     

Early Understanding of Subject and Object Wh‐Questions

In this study, we used the splitscreen preferential looking paradigm to test 13‐, 15‐, and 20‐month‐olds' developing understanding of simple matrix what‐questions of the forms “What hit the X?” (subject‐question) and “What did the X hit?” (object‐question). Infants responded appropriately to subject‐questions by 15 months of age, and to both subject‐ and object‐questions by 20 months. At no age did infants look longer toward the object overtly mentioned in the question, as might be expected based on a surface account of early language acquisition. This suggests that infants may have some understanding of these complex structures long before they are produced.     

Do Infants Recognize Engagement in Social Interactions? The Case of Face‐to‐Face Conversation

This study explores 12‐month‐olds' understanding of face‐to‐face conversation, a key contextual structure associated with engagement in a social interaction. Using a violation‐of‐expectations paradigm, we habituated infants to a “face‐to‐face” conversation, and in a test phase compared their looking times between “back‐to‐back” (conceptually novel) and “face‐to‐face” (conceptually familiar) conversations, while simultaneously manipulating perceptual familiarity in a 2 × 2 factorial design. We also analyzed dynamic changes in pupil dilation, which are considered a reliable measure of cognitive load that may index processing of social interactions. Infants looked relatively longer at perceptual changes (new speaker positions) but not at conceptual change (back‐to‐back conversation), suggesting that face‐to‐face conversation may not elicit particular expectations, and so may not carry any particular conceptual significance. Moreover, on the first test trial, larger pupil dilation was observed for familiar conditions, suggesting that familiarity with perceptual features could enhance processing of conversations. Thus, this study undermines assertions regarding infants' conceptual understanding of the social signals underlying engagement. Infants may rather recognize such signals through their perceptual familiarity and associated positive feelings. This may then increase their engagement when observing and participating in others' collaborative activities, in turn allowing for the development of knowledge regarding others' intentions.     

Infants’ response to a mobile phone modified still‐face paradigm: Links to maternal behaviors and beliefs regarding technoference

Interruptions to parent–child interactions due to technology, or “technoference,” have been correlated with a host of negative child developmental outcomes. Yet, the influence of technoference on parent–infant interactions and infant behaviors has received less attention and more experimental work is warranted. For this study, parent–infant dyads (n = 227) completed a modified still‐face paradigm (SFP) using a mobile phone during the still‐face phase. Infant responses were coded for positive and negative affect, object and parent orientation, self‐comforting, and escape behaviors during the task. Results showed a robust still‐face effect, with infants displaying increased negative affect, decreased positive affect, increased self‐comforting, object orientation, and escape behaviors during the “still‐face” or phone distracted phase of the paradigm and frequently failing to return to baseline during the reunion phase. Older infants (older than 9 months) likewise demonstrated higher levels of negative affect across all three phases of the paradigm relative to younger infants (less than 9 months). Parent reports of technoference behavior were related to increased object orientation for younger infants. Parental technoference behaviors were also linked to more escape behaviors for younger infants and decreased object orientation in older infants during the still‐face portion of the SFP. Higher levels of technoference also appear to attenuate the negative emotional response of infants during still face. Results are discussed in relation to infants’ increasing exposure to digital technology in the context of early relationships.     

Learning Words Over Time: The Role of Stimulus Repetition in Mutual Exclusivity

During the second year of life, infants develop a preference to attach novel labels to novel objects. This behavior is commonly known as “mutual exclusivity” (Markman, 1989). In an intermodal preferential looking experiment with 19.5‐ and 22.5‐month‐olds, stimulus repetition was critical for observing mutual exclusivity. On the first occasion that a novel label was presented with 1 familiar object and 1 novel object, looking behavior was unsystematic. However, on reexposure to the same stimuli, 22.5‐month‐olds looked preferentially at the novel object prior to the re‐presentation of the novel label. These findings suggest a powerful memory mechanism for novel labels and objects, enabling mutual exclusivity to emerge across repeated exposures to potential referents.     

Eighteen‐Month‐Old Infants Correct Non‐Conforming Actions by Others

At around their third birthday, children begin to enforce social norms on others impersonally, often using generic normative language, but little is known about the developmental building blocks of this abstract norm understanding. Here, we investigate whether even toddlers show signs of enforcing on others interpersonally how “we” do things. In an initial dyad, 18‐month‐old infants learnt a simple game‐like action from an adult. In two experiments, the adult either engaged infants in a normative interactive activity (stressing that this is the way “we” do it) or, as a non‐normative control, marked the same action as idiosyncratic, based on individual preference. In a test dyad, infants had the opportunity to spontaneously intervene when a puppet partner performed an alternative action. Infants intervened, corrected, and directed the puppet more in the normative than in the non‐normative conditions. These findings suggest that, during the second year of life, infants develop second‐personal normative expectations about their partner's behavior (“You should do X!”) in social interactions, thus making an important step toward understanding the normative structure of human cultural activities. These simple normative expectations will later be scaled up to group‐minded and abstract social norms.     

Beneficial effects of the mother's voice on infants’ novel word learning

The maternal voice appears to have a special role in infants’ language processing. The current eye‐tracking study investigated whether 24‐month‐olds (n = 149) learn novel words easier while listening to their mother's voice compared to hearing unfamiliar speakers. Our results show that maternal speech facilitates the formation of new word–object mappings across two different learning settings: a live setting in which infants are taught by their own mother or the experimenter, and a prerecorded setting in which infants hear the voice of either their own or another mother through loudspeakers. Furthermore, this study explored whether infants’ pointing gestures and novel word productions over the course of the word learning task serve as meaningful indexes of word learning behavior. Infants who repeated more target words also showed a larger learning effect in their looking behavior. Thus, maternal speech and infants’ willingness to repeat novel words are positively linked with novel word learning.     

Learned Labels Shape Pre‐speech Infants’ Object Representations

Infants rapidly learn both linguistic and nonlinguistic representations of their environment and begin to link these from around 6 months. While there is an increasing body of evidence for the effect of labels heard in‐task on infants’ online processing, whether infants’ learned linguistic representations shape learned nonlinguistic representations is unclear. In this study 10‐month‐old infants were trained over the course of a week with two 3D objects, one labeled, and one unlabeled. Infants then took part in a looking time task in which 2D images of the objects were presented individually in a silent familiarization phase, followed by a preferential looking trial. During the critical familiarization phase, infants looked for longer at the previously labeled stimulus than the unlabeled stimulus, suggesting that learning a label for an object had shaped infants’ representations as indexed by looking times. We interpret these results in terms of label activation and novelty response accounts and discuss implications for our understanding of early representational development.     

The impact of face masks on infants' learning of faces: An eye tracking study

This preregistered study examined how face masks influenced face memory in a North American sample of 6- to 9-month-old infants (N = 58) born during the COVID-19 pandemic. Infants' memory was tested using a standard visual paired comparison (VPC) task. We crossed whether or not the faces were masked during familiarization and test, yielding four trial types (masked-familiarization/masked-test, unmasked-familiarization/masked-test, masked-familiarization/unmasked-test, and unmasked-familiarization/unmasked-test). Infants showed memory for the faces if the faces were unmasked at test, regardless of whether or not the face was masked during familiarization. However, infants did not show robust evidence of memory when test faces were masked, regardless of the familiarization condition. In addition, infants' bias for looking at the upper (eye) region was greater for masked than unmasked faces, although this difference was unrelated to memory performance. In summary, although the presence of face masks does appear to influence infants' processing of and memory for faces, they can form memories of masked faces and recognize those familiar faces even when unmasked.     

Visual short‐term memory for overtly attended objects during infancy

We investigated limitations in young infants’ visual short‐term memory (VSTM). We used a one‐shot change detection task to ask whether 4‐ and 8.5‐month‐old infants (N = 59) automatically encode fixated items in VSTM. Our task included trials that consisted of the following sequence: first a brief (500 ms) presentation with a sample array of two items, next a brief (300 ms) delay period with a blank screen, and finally a test array (2,000 ms) identical to the sample array except that the color of one of the two items is changed. In Experiment 1, we induced infants to fixate one item by rotating it during the sample (the other item remained stationary). In Experiment 2, none of the items rotated. In both experiments, 4‐month‐old infants looked equally at the fixated item when it did and did not change color, providing no evidence that they encoded in VSTM the fixated item. In contrast, 8.5‐month‐old infants in Experiment 1 preferred the fixated item when it changed color from sample to test. Thus, 4‐month‐old infants do not appear to automatically encode fixated items in VSTM.     

The Other‐Race Effect in a Longitudinal Sample of 3‐, 6‐ and 9‐Month‐Old Infants: Evidence of a Training Effect

We investigated the development of the other‐race effect “ORE” in a longitudinal sample of 3‐, 6‐, and 9‐month‐old Caucasian infants. Previous research using cross‐sectional samples has shown an unstable ORE at 3 months, an increase at 6 months and full development at 9 months. In Experiment 1, we tested whether 9‐month‐olds showed the ORE with Caucasian and African faces. As expected, the 9‐month‐olds discriminated faces within their own ethnicity (Caucasian) but not within the unfamiliar ethnicity (African). In months. In Experiment 2, we longitudinally tested infants at 3, 6, and 9 months by presenting either the Caucasian or the African faces used in Experiment 1. In contrast to previous cross‐sectional studies and Experiment 1, we found that infants discriminated between all stimuli. Hence, we did not find the ORE in this longitudinal study even at 9 months. We assume that the infants in our longitudinal study showed no ORE because of previous repetitive exposure to African faces at 3 and 6 months. We argue that only a few presentations of faces from other ethnic categories sufficiently slow the development of the ORE.     

14‐Month‐olds anticipate others’ actions based on their belief about an object's identity

Past research has accumulated evidence regarding infants’ false‐belief understanding, measuring their gaze patterns or active helping behaviors. However, the underlying mechanisms are still debated, specifically, whether young infants can compute that others represent the world under a certain aspect. Such performance requires holding in mind two representations about the same object simultaneously and attributing only one to another person. While 14‐month‐olds can encode an object under different aspects when forming first‐person representations, it is unclear whether infants at this very age could also predict others’ behavior based on their beliefs about an object's identity. Here, we investigate this question in a novel eye‐tracking‐based unexpected‐identity task. We measured 14‐month‐olds’ anticipatory looks combined with their looking time, using a violation‐of‐expectation paradigm. Results show that 14‐month‐olds look longer to an actor's reach that is incongruent with her false belief about the identity of an object compared to a congruent reach. Furthermore, infants correctly anticipated the actor's reach based on her false belief. Thus, as soon as infants represent dual identities they can integrate them in belief attributions and use them for consequent behavioral predictions. Such data provide evidence for the flexibility of false‐belief attributions and support proposals arguing for infants’ rich theory‐of‐mind abilities.     

Infant Preference for Natural Texture Statistics is Modulated by Contrast Polarity

Adult observers are sensitive to statistical regularities present in natural images. Developmentally, research has shown that children do not show sensitivity to these natural regularities until approximately 8–10 years of age. This finding is surprising given that even infants gradually encode a range of high‐level statistical regularities of their visual environment in the first year of life, We suggest that infants may in fact exhibit sensitivity to natural image statistics under circumstances where images of complex, natural textures, such as a photograph of rocks, are used as experimental stimuli and natural appearance is substantially manipulated. We tested this hypothesis by examining how infants' visual preference for real versus computer‐generated synthetic textures was modulated by contrast negation, which produces an image similar to a photographic negative. We observed that older infants' (9‐months of age) preferential looking behavior in this task was affected by contrast polarity, suggesting that the infant visual system is sensitive to deviations from natural texture appearance, including (1) discrepancies in appearance that differentiate natural and synthetic textures from one another and (2) the disruption of contrast polarity following negation. We discuss our results in the context of adult texture processing and the “perceptual narrowing” of visual recognition during the first year of life.     

The Effects of Calibration Target,Screen Location,and Movement Type on Infant Eye‐Tracking Data Quality

During infant eye‐tracking, fussiness caused by the repetition of calibration stimuli and body movements during testing are frequent constraints on measurement quality. Here, we systematically investigated these constraints with infants and adults using EyeLink 1000 Plus. We compared looking time and dispersion of gaze points elicited by stimuli resembling commonly used calibration animations. The adult group additionally performed body movements during gaze recording that were equivalent to movements infants spontaneously produce during testing. In our results, infants’ preference for a particular calibration target did not predict data quality elicited by that stimulus, but targets exhibiting the strongest contrasts in their center or targets with globally distributed complexity resulted in the highest accuracy. Our gaze measures from the adult movement tasks were differentially affected by the type of movement as well as the location where the target appeared on the screen. These heterogeneous effects of movement on measures should be taken into account when planning infant eye‐tracking experiments. Additionally, to improve data quality, infants’ tolerance for repeated calibrations can be facilitated by alternating between precise calibration targets.     

Mothers' Verbal and Nonverbal Strategies in Relation to Infants' Object‐Directed Actions in Real Time and Across the First Three Years in Ethnically Diverse Families

We examined maternal behavioral strategies in relation to infants' object‐directed actions in real time and over developmental time in 206 mother–infant dyads from African American, Dominican immigrant, and Mexican immigrant backgrounds. Mothers were asked to share a set of beads and strings with their infants when children were 14, 24, and 36 months. We coded three types of maternal strategies—eliciting attention, instructive assistance, and encouragement—which could be expressed verbally (e.g., “look”, “turn it”, “good job!”) or physically (i.e., through gestures, hands‐on guidance, or transfer of objects). We also coded infants' unassisted bead‐stringing. Across ethnic groups and ages, mothers' hands‐on guidance and object transfer increased the likelihood that infants would follow with unassisted bead‐stringing during real‐time interaction. Over developmental time, mothers modified their strategies: They displayed fewer attention‐getting strategies and more encouragement across infant ages, and peaked in their provision of instructive assistance when infants were 24 months. Additionally, Mexican mothers displayed more nonverbal strategies (e.g., gestures, hands‐on guidance) than did African American and/or Dominican mothers, who displayed more verbal strategies (e.g., attention‐getting and encouraging language). Developmental and real‐time patterns in mother–infant object‐related interactions generalize across ethnicities, although mothers' emphases on specific strategies are culture specific.     

Neural Correlates of Encoding Predict Infants’ Memory in the Paired‐Comparison Procedure

The present study used event‐related potentials (ERPs) to monitor infant brain activity during the initial encoding of a previously novel visual stimulus, and examined whether ERP measures of encoding predicted infants’ subsequent performance on a visual memory task (i.e., the paired‐comparison task). A late slow wave component of the ERP measured at encoding predicted infants’ immediate performance in the paired‐comparison task: amplitude of the late slow wave at right‐central and temporal leads decreased with stimulus repetition, and greater decreases at right‐anterior‐temporal leads during encoding were associated with better memory performance at test. By contrast, neither the amplitude nor latency of the negative central (Nc) component predicted infants’ subsequent performance in the paired‐comparison task. These findings are discussed with respect to a biased competition model of visual attention and memory.     

Just Before I Recognize Myself: The Role of Featural and Multisensory Cues Leading up to Explicit Mirror Self‐Recognition

Leading up to explicit mirror self‐recognition, infants rely on two crucial sources of information: the continuous integration of sensorimotor and multisensory signals, as when seeing one's movements reflected in the mirror, and the unique facial features associated with the self. While visual appearance and multisensory contingent cues may be two likely candidates of the processes that enable self‐recognition, their respective contribution remains poorly understood. In this study, 18‐month‐old infants saw side‐by‐side pictures of themselves and a peer, which were systematically and simultaneously touched on the face with a hand. While watching the stimuli, the infant's own face was touched either in synchrony or out of synchrony and their preferential looking behavior was measured. Subsequently, the infants underwent the mirror‐test task. We demonstrated that infants who were coded as nonrecognizers at the mirror test spent significantly more time looking at the picture of their own face compared to the other‐face, irrespective of whether the multisensory input was synchronous or asynchronous. Our results suggest that right before the onset of mirror self‐recognition, featural information about the self might be more relevant in the process of recognizing one's face, compared to multisensory cues.