Cross‐Task Stability in Infant Attention: New Perspectives Using the Still‐Face Procedure

Infant visual attention has been studied extensively within cognitive paradigms using measures such as look duration and reaction time, but less work has examined how infant attention operates in social contexts. In addition, little is known about the stability of individual differences in attention across cognitive and social contexts. In this study, a cross‐sectional sample of 50 infants (4 and 6 months of age) were first tested in a look duration and reaction time task with static visual stimuli. Next, their mothers participated with the infants in the still‐face procedure, a mildly distressing social interaction paradigm that involves violation of expectancy. Individual differences in looking and emotion were stable across the phases of the still‐face task. Further, individual differences in looking measures from the visual attention task were related to the pattern of looking shown across the phases of the still‐face procedure. Results indicate that individual differences in attentional measures show moderate stability within cognitive and social contexts, and that the ability of infants to shift and disengage looks may affect their ability to regulate interaction in social contexts.     

Real‐world scene perception in infants: What factors guide attention allocation?

The foci of visual attention were modeled as a function of perceptual salience, adult fixation locations, and attentional control mechanisms (measured in separate tasks) in infants (N = 45, 3‐ to 15‐month‐olds) as they viewed static real‐world scenes. After controlling for the center bias, the results showed that low‐level perceptual salience predicts where infants look. In addition, high‐level factors also played a role: Infants fixated parts of the scenes frequently fixated by adults and this effect was stronger for older than younger infants. In line with this finding, infant fixation durations were longer on regions more frequently fixated by adults, implying longer time taken to process the available information. Fixation durations decreased with age, and this decline interacted with orienting skills such that fixation durations decreased faster with age for infants with high orienting skills, relative to infants with low orienting skills. There was a further interaction between fixation durations and selective attention abilities: Infants with low selective attention skills showed a decrease in fixation durations with age, whereas infants with higher selective attention skills showed a slight increase in fixation durations with age. These findings imply that infants' visual processing of static real‐world stimuli develops in accord with attentional control.     

Developmental Changes in Infant Attention to Dynamic and Static Stimuli

This study examined 4‐ and 6‐month‐olds' responses to static or dynamic stimuli using behavioral and heart‐rate‐defmed measures of attention. Infants looked longest to dynamic stimuli with an audio track and least to a static stimulus that was mute. Overall, look duration declined with age to the different stimuli. The amount of time spent in sustained attention at 4 months, but not at 6 months, was related to stimulus discrimination. These results indicate that the decline in look duration typically observed during the middle of the 1st year for static stimuli does generalize to dynamic stimuli. The results further suggest that the amount of time spent in sustained attention during habituation may be an important indicator of processing in younger infants.     

Differences in Visual Attention Patterns to Sexually Mature and Immature Stimuli Between Heterosexual Sexual Offenders,Nonsexual Offenders,and Nonoffending Men

Men, whether gynephilic or androphilic, show both early and late attention toward adults and not toward children. We examined early and late visual attention to sexually mature versus immature stimuli in four groups of heterosexual men: sexual offenders against children (SOAC = 18), sexual offenders against adults (SOAA = 16), nonsexual offenders (NSO = 18), and nonoffending men (NOM = 19). We simultaneously presented adult and child stimuli and measured time to first fixation, number of first fixations, total duration of fixation, and fixation count to four areas of interest: entire body, then face, chest, and pelvis. We found a significant interaction where only SOAC tended to fixate more first times to child than to adult stimuli. Conversely, we found longer total duration of fixations for the bodies of adults compared to the bodies of children in all groups; however, in both the total duration of fixations and the fixation count for the whole body, but especially in the chest, SOAC tended to fixate longer and more often on child stimuli than the other two groups of offenders, but not longer or more often than NOM. This study adds to the limited research using eye-tracking techniques in samples of SOAC.     

The Role of Dyadic Coordination in Organizing Visual Attention in 5‐Month‐Old Infants

In human infants, the ability to share attention with others is facilitated by increases in attentional selectivity and focus. Differences in early attention have been associated with socio‐cognitive outcomes including language, yet the social mechanisms of attention organization in early infancy have only recently been considered. Here, we examined how social coordination between 5‐month‐old infants and caregivers relate to differences in infant attention, including looking preferences, span, and reactivity to caregivers’ social cues. Using a naturalistic play paradigm, we found that 5‐month‐olds who received a high ratio of sensitive (jointly focused) contingent responses showed strong preferences for objects with which their caregivers were manually engaged. In contrast, infants whose caregivers exhibited high ratios of redirection (attempts to shift focus) showed no preferences for caregivers’ held objects. Such differences have implications for recent models of cognitive development, which rely on early looking preferences for adults’ manually engaged objects as a pathway toward joint attention and word learning. Further, sensitivity and redirectiveness predicted infant attention even in reaction to caregiver responses that were non‐referential (neither sensitive nor redirective). In response to non‐referentials, infants of highly sensitive caregivers oriented less frequently than infants of highly redirective caregivers, who showed increased distractibility. Our results suggest that specific dyadic exchanges predict infant attention differences toward broader social cues, which may have consequences for social‐cognitive outcomes.     

Neural Correlates of Individual Differences in Infant Visual Attention and Recognition Memory

Past studies have identified individual differences in infant visual attention based upon peak look duration during initial exposure to a stimulus. Colombo and colleagues found that infants that demonstrate brief visual fixations (i.e., short lookers) during familiarization are more likely to demonstrate evidence of recognition memory during subsequent stimulus exposure than infants that demonstrate long visual fixations (i.e., long lookers). This study utilized event‐related potentials (ERPs) to examine possible neural mechanisms associated with individual differences in visual attention and recognition memory for 6‐ and 7.5‐month‐old infants. Short‐ and long‐looking infants viewed images of familiar and novel objects during ERP testing. There was a stimulus type by looker type interaction at temporal and frontal electrodes on the late slow wave (LSW). Short lookers demonstrated an LSW that was significantly greater in amplitude in response to novel stimulus presentations. No significant differences in LSW amplitude were found based on stimulus type for long lookers. These results indicate deeper processing and recognition memory of the familiar stimulus for short lookers.     

Developmental Differences in Infants' Attention to Social and Nonsocial Threats

Research has demonstrated that humans detect threatening stimuli more rapidly than nonthreatening stimuli. Although the literature presumes that biases for threat should be normative, present early in development, evident across multiple forms of threat, and stable across individuals, developmental work in this area is limited. Here, we examine the developmental differences in infants' (4‐ to 24‐month‐olds) attention to social (angry faces) and nonsocial (snakes) threats using a new age‐appropriate dot‐probe task. In Experiment 1, infants' first fixations were more often to snakes than to frogs, and they were faster to fixate probes that appeared in place of snakes vs. frogs. There were no significant age differences, suggesting that a perceptual bias for snakes is present early in life and stable across infancy. In Experiment 2, infants fixated probes more quickly after viewing any trials that contained an angry face compared to trials that contained a happy face. Further, there were age‐related changes in infants' responses to face stimuli, with a general increase in looking time to faces before the probe and an increase in latency to fixate the probe after seeing angry faces. Together, this work suggests that different developmental mechanisms may be responsible for attentional biases for social vs. nonsocial threats.     

Early Word Segmentation in Naturalistic Environments: Limited Effects of Speech Register

We examined 7.5‐month‐old infants' ability to segment words from infant‐ and adult‐directed speech (IDS and ADS). In particular, we extended the standard design of most segmentation studies by including a phase where infants were repeatedly exposed to target word recordings at their own home (extended exposure) in addition to a laboratory‐based familiarization. This enabled us to examine infants' segmentation of words from speech input in their naturalistic environment, extending current findings to learning outside the laboratory. Results of a modified preferential‐listening task show that infants listened longer to isolated tokens of familiarized words from home relative to novel control words regardless of register. However, infants showed no recognition of words exposed to during purely laboratory‐based familiarization. This indicates that infants succeed in retaining words in long‐term memory following extended exposure and recognizing them later on with considerable flexibility. In addition, infants segmented words from both IDS and ADS, suggesting limited effects of speech register on learning from extended exposure in naturalistic environments. Moreover, there was a significant correlation between segmentation success and infants' attention to ADS, but not to IDS, during the extended exposure phase. This finding speaks to current language acquisition models assuming that infants' individual attention to language stimuli drives successful learning.     

Infants scan static and dynamic facial expressions differently

Despite being inherently dynamic phenomena, much of our understanding of how infants attend and scan facial expressions is based on static face stimuli. Here we investigate how six-, nine-, and twelve-month infants allocate their visual attention toward dynamic-interactive videos of the six basic emotional expressions, and compare their responses with static images of the same stimuli. We find infants show clear differences in how they attend and scan dynamic and static expressions, looking longer toward the dynamic-face and lower-face regions. Infants across all age groups show differential interest in expressions, and show precise scanning of regions “diagnostic” for emotion recognition. These data also indicate that infants' attention toward dynamic expressions develops over the first year of life, including relative increases in interest and scanning precision toward some negative facial expressions (e.g., anger, fear, and disgust).     

Seven-months-old infants show increased arousal to static emotion body expressions: Evidence from pupil dilation

Human body postures provide perceptual cues that can be used to discriminate and recognize emotions. It was previously found that 7-months-olds’ fixation patterns discriminated fear from other emotion body expressions but it is not clear whether they also process the emotional content of those expressions. The emotional content of visual stimuli can increase arousal level resulting in pupil dilations. To provide evidence that infants also process the emotional content of expressions, we analyzed variations in pupil in response to emotion stimuli. Forty-eight 7-months-old infants viewed adult body postures expressing anger, fear, happiness and neutral expressions, while their pupil size was measured. There was a significant emotion effect between 1040 and 1640 ms after image onset, when fear elicited larger pupil dilations than neutral expressions. A similar trend was found for anger expressions. Our results suggest that infants have increased arousal to negative-valence body expressions. Thus, in combination with previous fixation results, the pupil data show that infants as young as 7-months can perceptually discriminate static body expressions and process the emotional content of those expressions. The results extend information about infant processing of emotion expressions conveyed through other means (e.g., faces).     

Infant Attention to Dynamic Audiovisual Stimuli: Look Duration From 3 to 9 Months of Age

The goal of this study was to examine developmental change in visual attention to dynamic visual and audiovisual stimuli in 3‐, 6‐, and 9‐month‐old infants. Infant look duration was measured during exposure to dynamic geometric patterns and Sesame Street video clips under three different stimulus modality conditions: unimodal visual, synchronous audiovisual, and asynchronous audiovisual. Infants looked longer toward Sesame Street stimuli than geometric patterns, and infants also looked longer during multimodal audiovisual (synchronous and asynchronous) presentations than during unimodal visual presentations. There was a three‐way interaction of age, stimulus type, and stimulus modality. Significant differences were found within and between age groups related to stimulus modality (visual or audiovisual) while viewing Sesame Street clips. No significant interaction was found between age and stimulus type while infants viewed dynamic geometric patterns. These findings indicate that patterns of developmental change in infant attention vary based on stimulus complexity and modality of presentation.     

Speech Perception by 6‐to 8‐Month‐Olds in the Presence of Distracting Sounds

The role of selective attention in infant phonetic perception was examined using a distraction masker paradigm. We compared perception of /bu/ versus /gu/ in 6‐ to 8‐month‐olds using a visual fixation procedure. Infants were habituated to multiple natural productions of 1 syllable type and then presented 4 test trials (old‐new‐old‐new). Perception of the new syllable (indexed as novelty preference) was compared across 3 groups: habituated and tested on syllables in quiet (Group 1), habituated and tested on syllables mixed with a nonspeech signal (Group 2), and habituated with syllables mixed with a non‐speech signal and tested on syllables in quiet (Group 3). In Groups 2 and 3, each syllable was mixed with a segment spliced from a recording of bird and cricket songs. This nonspeech signal has no overlapping frequencies with the syllable; it is not expected to alter the sensory structure or perceptual coherence of the syllable. Perception was negatively affected by the presence of the auditory distracter during habituation; individual performance levels also varied more in these groups. The findings show that perceiving speech in the presence of irrelevant sounds poses a cognitive challenge for young infants. We conclude that selective attention is an important skill that supports speech perception in infants; the significance of this skill for language learning during infancy deserves investigation.     

The Trajectory of Concurrent Motor and Vocal Behaviors Over the Transition to Crawling in Infancy

To document the trajectory of motor and vocal behaviors in real and developmental time, we observed infants at each of four biweekly naturalistic play sessions over the transition to crawling. An exhaustive and mutually exclusive coding scheme documented all vocalizations and postures. Odds ratios of the likelihood of a given posture‐vocalization dyad revealed that vocalization and crawling were significantly unlikely to co‐occur at the session marking the onset of crawling. We speculate that infants’ allocation of attention over the transition to crawling prompted behavioral trade‐offs. During mastery of a novel skill, infants may have had difficulty allocating attention to multiple tasks, but with experience, a decrease in attentional load for the new skill allowed performance of simultaneous behaviors in other domains to occur.     

Individual Differences in Infants' Recognition of Briefly Presented Visual Stimuli

Infants' recognition memory has been shown to be related to individual differences in look duration and level of heart period variability. This study examined the effect of individual differences in these 2 measures on infants' recognition of briefly presented visual stimuli using a paired‐comparison recognition‐memory paradigm. A sample of 35 full‐term infants was studied longitudinally at 14, 20, and 26 weeks of age. Recognition memory for briefly presented stimuli was tested in 6 experimental conditions, with delays corresponding to different heart‐rate‐defined phases of attention. The 20‐and 26‐week‐old infants, and infants with high levels of heart period variability, generally showed more evidence of recognition memory for briefly presented visual stimuli. Greater evidence of recognition memory was observed when stimuli were presented during sustained attention. Infants with more mature baseline physiological responses show greater evidence of recognition memory, and stimulus and procedural factors may be more important for the study of individual differences in infant visual attention than has previously been suggested.     

Infants' Preferences for Familiarity and Novelty During the Course of Visual Processing

At 4 1/2 months, infants were shown a series of brief choice trials between a stimulus that always remained the same and another that was different on every trial. The point when a consistent preference for the novel stimulus commenced was identified for each infant, and their preferences for the familiar and novel stimuli in trials preceding that point were examined. Infants who saw objects or faces as stimuli both exhibited selective attention to the familiar stimulus prior to preferring novel stimuli, although infants shown kaleidoscope patterns did not. These results document a preference for familiarity early in processing with a procedure that is not subject to ambiguities due to individual differences in processing speed or to collapsing data across infants. The results support a nonlinear model for memory formation during infancy and underscore recently voiced concerns that in research on cognitive development, infants' attention to perceptual familiarity‐novelty must be carefully disentangled from conceptual knowledge.     

Contributions of Look Duration and Gaze Shift Patterns to Infants’ Novelty Preferences

Data from 72 infants, tested using a serial paired‐comparison paradigm, were analyzed to better understand infant novelty preferences. Infants between the ages of 15 and 26 weeks were tested in three studies with familiar stimuli displayed adjacent to novel stimuli on each trial. Differences in look duration, look number, and gaze shifts directed at novel versus familiar stimuli were assessed to measure their contributions to group and individual novelty preferences. Infants produced longer looks for novel stimuli in all three studies, and stimulus differences in look duration accounted for more than 50% of the variability in individual novelty preferences. Infants that produced more looks to novel rather than familiar stimuli did not produce overall novelty preferences unless they also looked longer at novel stimuli. Gaze shift patterns did not predict individual novelty preferences, and novel stimuli did not determine where infants looked. The infants’ visual exploration was constrained by memories for the direction of the previous look as well as by the attention‐holding features of novel stimuli.     

Faces Attract Infants' Attention in Complex Displays

Infant's face preferences have previously been assessed in displays containing 1 or 2 faces. Here we present 6‐month‐old infants with a complex visual array containing faces among multiple visual objects. Despite the competing objects, infants direct their first saccade toward faces more frequently than expected by chance (Experiment 1). The attention‐grabbing effect of faces is not selective to upright faces (Experiment 2) but does require the presence of internal facial elements, as faces whose interior has been phase‐scrambled did not attract infants' attention (Experiment 3). On the contrary, when the number of fixations is considered, upright faces are scanned more extensively than both inverted and phase‐scrambled faces. The difference in selectivity between the first look measure and the fixation count measure is discussed in light of a distinction between attention‐grabbing and attention‐holding mechanisms.     

Bimodal Dynamics of Faces and Voices Influence Older Infants' Perception of Emotion

Given the importance of infants' perception of bimodal speech for emerging language and emotion development, this study used eye‐tracking technology to examine infants' attention to face+voice displays differing by emotion (fear, sad, happy) and visual stimulus (dynamic versus static). Peripheral distracters were presented to measure attention disengagement. It was predicted that infants would look longer at and disengage more slowly from dynamic bimodal emotion displays, especially when viewing dynamic fear. However, the results from twenty‐two 10‐month‐olds found significantly greater attention on dynamic versus static trials, independent of emotion. Interestingly, infants looked equally to mouth and eye regions of speakers' faces except when viewing/hearing dynamic fear; in this case, they fixated more on the speakers' mouth region. Average latencies to distracters were longer on dynamic compared to static bimodal stimuli, but not differentiated by emotion. Thus, infants' attention was enhanced (in terms of both elicitation and maintenance) by dynamic, bimodal emotion displays. Results are compared to conflicting findings using static emotion displays, with suggestions for future research using more ecologically relevant dynamic, multimodal displays to gain a richer understanding of infants' processing of emotion.     

Rules Infants Look By: Testing the Assumption of Transitivity in Visual Salience

What drives infants’ attention in complex visual scenes? Early models of infant attention suggested that the degree to which different visual features were detectable determines their attentional priority. Here, we tested this by asking whether two targets—defined by different features, but each equally salient when evaluated independently—would drive attention equally when pitted head‐to‐head. In Experiment 1, we presented 6‐month‐old infants with an array of Gabor patches in which a target region varied either in color or spatial frequency from the background. Using a forced‐choice preferential‐looking method, we measured how readily infants fixated the target as its featural difference from the background was parametrically increased. Then, in Experiment 2, we used these psychometric preference functions to choose values for color and spatial frequency targets that were equally salient (preferred), and pitted them against each other within the same display. We reasoned that if salience is transitive, then the stimuli should be iso‐salient and infants should therefore show no systematic preference for either stimulus. On the contrary, we found that infants consistently preferred the color‐defined stimulus. This suggests that computing visual salience in more complex scenes needs to include factors above and beyond local salience values.     

Evaluation of the Psychometric Properties of the Gap‐Overlap Task in 10‐Month‐Old Infants

Understanding the development of attention is key to understanding cognitive maturation. The gap‐overlap task can be administered at all ages and is widely used to study the development of overt visual attention. However, studies using the gap‐overlap task report different measures and little is known about the tasks’ psychometric properties, especially in infants. We tested the 1‐week test–retest reliability of two frequently used gap‐overlap measures of attentional disengagement in 10‐month‐old infants; the gap effect as measured by the difference between the gap and overlap condition and the gap effect as measured by the difference between the gap and baseline condition. Sixty‐seven infants performed the gap‐overlap task twice, of which 45 infants had sufficient data quality for further analyses. Test–retest reliability of the overlap‐gap gap effect was higher (r = .50) than the baseline‐gap gap effect (r = .29). Moreover, the shared variance between overlap and baseline saccadic reaction times was moderate to high across sessions. In light of these results and the methodological challenges and limitations of infant research, we consider the overlap‐gap gap effect to be a good measure to study the development of attentional disengagement in infants and suggest the exclusion of the baseline condition in future studies.