Individual Differences in Infant Visual Attention: Are Short Lookers Faster Processors or Feature Processors?

Individual differences in the duration of infants' visual fixations are reliable and stable and have been linked to differential cognitive performance; short-looking infants typically perform better than long-looking infants. 4 experiments tested the possibility of whether short lookers' superiority on perceptual-cognitive tasks is attributable to attention to the featural details of visual stimuli, or simply to differences in the speed or efficiency of visual processing. To do this, the performance of long- and short-looking 4-month-olds was examined on separate discrimination tasks that could be solved only by processing either featural or global information. The global task was easier than the featural task, but as the amount of time allotted for infants to solve either type of task was decreased, short lookers' performance was superior to that of long lookers. These results thus lend support to a speed or efficiency of stimulus processing interpretation of infant fixation duration.     

Modifying the distribution of attention in infants

In three experiments, the distribution and malleability of infant visual attention were studied in 5-month-olds (N = 72) while they inspected large geometric designs. In Experiment 1, we established that infants maintained their distribution of attention from a pretest to a familiarization phase. We also replicated and extended our previous findings that infants who examined targets with briefer, more numerous looks and shifts-short lookers-had novelty scores above chance, whereas long lookers demonstrated chance responding. In Experiment 2, different portions of the display were successively illuminated with red light. This manipulation induced long lookers to scan like short lookers during familiarization; they then showed novelty scores well above chance. A third experiment ruled out the simple presence of a red light as the source of this effect. In sum, then, these results suggest that the distribution of attention is malleable, and that a broader distribution of attention, as reflected in briefer and more numerous looks and shifts, can improve processing.     

Differential rates of visual information processing in full-term and preterm infants

This study investigated the effect of increasing familiarization time on the visual recognition memory of 6- and 12-month-old full-term and preterm infants. Infants were given trials in which they viewed a shape for either 10-, 15-, 20-, or 30-sec familiarization and were then tested for visual recognition memory using the paired comparison technique. While the older infants showed evidence of recognition memory after less familiarization time than the younger ones, at both ages preterms required considerably longer familiarization than full-terms. The pattern of performance replicates our earlier finding of developmental lags in the visual information processing of 6-month-old preterms and extends these findings to 12-month-olds. These results suggest that there are persistent differences between preterm and full-term infants throughout at least the first year of life in this very fundamental aspect of cognition.     

Noncontingent stimulation, stimulus familiarization, and subsequent learning in young infants

2 experiments assessed the effects of prior noncontingent or familiarization experience on subsequent operant conditioning (kick-produced mobile movement) in young infants. In Experiment 1, infants received either long- or short-term noncontingent exposure to their own rotating mobile or simply viewed this mobile for several days while it remained motionless. In Experiment 2, long-term exposure was provided by the same novel mobile used for subsequent training. In both experiments, prior noncontingent experience did not interfere with subsequent conditioning. In Experiment 2, however, simple long-term familiarization with the training mobile precluded "evidence" of learning. The results indicated that infants develop expectancies regarding how stimuli occurring in particular contexts should behave based on their prior experiences with these stimuli.     

Individual Differences in Infant Visual Attention: Recognition of Degraded Visual Forms by Four-Month-Olds

In 5 experiments, 4-month-old infants were tested for their ability to recognize degraded visual targets as a function of individual differences in fixation duration. Targets were degraded by removing 10% of the total contour either from vertices (vertex-absent) or from midsegments (vertex-present). Both qualitative and quantitative differences were found in long and short lookers' ability to recognize the degraded forms. Short-looking infants were able to recognize degraded forms in both vertex-absent and vertex-present conditions, but the vertex-absent discrimination was more difficult. Long-looking infants required longer familiarization times before showing evidence of recognition in the vertex-present condition, and were unable to recognize targets in which contour was removed at vertices. The findings are discussed within the framework of the persistence of early visual processing strategies, and reliance of long-looking infants on particular local elements in visual analysis.     

Understanding Category Members as "the Same Sort of Thing": Explicit Categorization in Ten-Month Infants

Although it is often acknowledged that classification exists in the first year of life, it has been suggested that infants are capable only of implicit categorization, recognizing that something is or is not familiar. In contrast, older children are thought to compare the stimuli or objects they categorize and to explicitly equate different category members. 2 habituation experiments were conducted in an attempt to determine whether 10-month-old infants are capable of explicit categorization. The approach taken was to insert nonmembers into the familiarization sequence in a categorization task. The nonmembers were designed so as to have a predictable effect on infants' performance whether or not these stimuli were included as infants processed the categorical information. The results suggest that infants do explicitly equate category members. Infants appeared to disregard the nonmembers in the familiarization sequence, basing their categorization response instead on the set of instances that were "the same sort of thing."     

Infant visual attention in the paired-comparison paradigm: test-retest and attention-performance relations

The visual behavior of infants in the paired-comparison paradigm was assessed with multiple discrimination tasks week-to-week at 4 and 7 months and longitudinally from 4 to 7 months. Results indicated that although task-to-task reliability was extremely variable and typically low, most measures of infants' attention averaged across multiple tasks were reliable from 1 week to the next as well as relatively stable over the longer longitudinal period. Across all groups, infants who had shorter fixations (i.e., more fixations per fixed-exposure period) during the familiarization phase showed higher novelty preferences. While infants' shift rate during test phases was a reliable individual characteristic at 7 months, it was not at 4 months; rather, data suggested that the difficulty of the stimulus discrimination may be related to young infants' shift rate.     

What does it look like and what can it do? Category structure influences how infants categorize

Despite a large body of research demonstrating the kinds of categories to which infants respond, few studies have directly assessed how infants' categorization unfolds over time. Four experiments used a visual familiarization task to evaluate 10-month-old infants' (N = 98) learning of exemplars characterized by commonalities in appearance or function. When learning exemplars with a common function, infants initially responded to the common feature, apparently forming a category, and only learned the individual features with more extensive familiarization. When learning exemplars with a common appearance, infants initially learned the individual features and apparently only formed a category with more extensive familiarization. The results are discussed in terms of models of category learning.     

Local Redundancy Governs Infants' Spontaneous Orienting to Visual‐Temporal Sequences

Two experiments demonstrate that 5‐month‐olds are sensitive to local redundancy in visual‐temporal sequences. In Experiment 1, 20 infants saw 2 separate sequences of looming colored shapes that possessed the same elements but contrasting transitional probabilities. One sequence was random whereas the other was based on bigrams. Without any prior exposure, infants looked longer at the random sequence. In Experiment 2, 17 infants looked equally long at bigram‐ and trigram‐based sequences. However, an analysis of local redundancy revealed that in both experiments disengagement from the sequences was governed by local repetitions rather than by global sequence statistics. This finding suggests that a spontaneous sensitivity to stimulus complexity helps orient infants to sequences they can learn from.     

Deficits in visual recognition in low birth weight infant pigtailed monkeys (Macaca nemestrina)

15 low birth weight and 15 normal birth weight pigtailed monkey infants were administered an adaptation of a standardized test of visual recognition memory, originally developed for human infants. Animals were given a series of problems in which 2 identical black-and-white patterns were presented for a familiarization period. The previously exposed pattern was then paired with a novel one, and looking time to each pattern was recorded. The normal birth weight animals directed a significant amount of their visual attention to the novel stimuli, thus demonstrating recognition abilities. As a group, the performance of the low birth weight infants remained at chance. These findings have important implications for an animal model to examine factors contributing to poor cognitive outcome in low birth weight human infants.     

Physiological self-regulation and information processing in infancy: cardiac vagal tone and habituation

This study investigates the role of physiological self-regulation (cardiac vagal tone) in information processing (habituation) in 81 infants. Nucleus ambiguus vagal tone (Vna, a measure of respiratory sinus arrhythmia) was used to index cardiac vagal tone. Physiological self-regulation was operationalized as the change in Vna from a baseline period of measurement to habituation. Decreases in Vna consistently related to habituation efficiency, operationalized as accumulated looking time (ALT), in all infants twice at 2 months and twice at 5 months; however, this relation was accounted for by infants who met an habituation criterion on each task. Among habituators, shorter lookers also had greater Vna suppression during habituation. Within-age and between-age suppression of vagal tone predicted ALT, but ALT did not predict suppression of vagal tone. Physiological self-regulation provided by the vagal system appears to play a role in information processing in infancy as indexed by habituation.     

Holistic face processing in newborns, 3-month-old infants, and adults: evidence from the composite face effect

Holistic face processing was investigated in newborns, 3-month-old infants, and adults through a modified version of the composite face paradigm and the recording of eye movements. After familiarization to the top portion of a face, participants (N = 70) were shown 2 aligned or misaligned faces, 1 of which comprised the familiar top part. In the aligned condition, no visual preference was found at any group age. In the misaligned condition, 3-month-olds preferred the face stimulus with the familiar top part, adults preferred the face stimulus with the novel one, and newborns did not manifest any visual preference. Results revealed that both infants' and adults' eye movements may be affected by holistic face information and demonstrated holistic face processing in 3-month-olds.     

Perceiving "outside the box" occurs early in development: evidence for boundary extension in three- to seven-month-old infants

This investigation examined whether infants display boundary extension-a tendency to remember more of a visual scene than was presented. Three- to 7-month-olds were familiarized with a photograph of a visual scene, and tested with wide-angle versus close-up views of the scene. Infants preferred the close-up, indicating that they perceived the wide angle (the one consistent with boundary extension) as more familiar. Converging experiments showed that: (a) infants did not spontaneously prefer the close-up, (b) adults did not judge the wide angle to be more similar to the familiarization stimulus, and (c) infants spontaneously preferred the close-up when the photographs depicted outline objects without backgrounds. The findings suggest that infants anticipate information that lies beyond the borders of a scene view.     

Recognition of Moving and Static Faces by Young Infants

This study compared 3- to 4-month-olds' recognition of previously unfamiliar faces learned in a moving or a static condition. Infants in the moving condition showed successful recognition with only 30 s familiarization, even when different images of a face were used in the familiarization and test phase (Experiment 1). In contrast, infants in the static condition showed successful recognition only when the familiarization duration was lengthened to 90 s and when the same image was used between the familiarization and test phase (Experiments 2 and 3). Furthermore, presentation of multiple static images of a face did not yield the same level of performance as the moving condition (Experiment 4). These results suggest that facial motion promotes young infants' recognition of unfamiliar faces.     

Heart Rate-Defined Phases of Attention, Look Duration, and Infant Performance in the Paired-Comparison Paradigm

Four-month-old infants (N = 68) were tested in a paired-comparison familiarization-novelty recognition task in which the length of choice trials was systematically manipulated. Peak look duration during pretest and familiarization periods significantly predicted a dichotomous measure of recognition performance, but recognition was unaffected by choice-trial length. Heart rate (HR) was simultaneously assessed during the task, and the amount of time infants spent in various HR-defined phases of attention was assessed. Longer durations of looking during pretest and familiarization were significantly associated with more time spent in both sustained attention (SA) and attention termination (AT). Of these two variables, only individual differences in AT accounted for significant variance in recognition memory performance. A final analysis addressed the possibility that individual differences in AT mediated the relation between look duration and recognition performance. These findings provide support for the hypothesis that individual differences in the disengagement of attention underlie the relation between look duration and cognitive performance in early to midinfancy.     

Infants' cross-modal transfer from solid objects to their graphic representations

12-month-old infants were familiarized either tactually or visually with objects and then tested for visual recognition memory using either (1) the familiar and a novel object, (2) colored pictures of the objects, or (3) outline drawings of them. In Study 1, infants showed recognition memory on all 3 visual intramodal problems but showed cross-modal transfer only when objects were used as test stimuli. With increased familiarization times in Study 2, transfer from tactually presented samples to both pictorial displays was achieved, indicating that after feeling an object the infants were able to recognize it visually solely on the basis of its contour. With reduced familiarization times in Study 3, there was no evidence for transfer from visually presented samples to the 2 pictorial displays, replicating the pattern of results observed cross-modally in Study 1 and suggesting that, at least in certain respects, cross-modal and intramodal perception follow similar principles.     

Local and Global Processing in Blind and Sighted Children in a Naming and Drawing Task

This study investigated the spatial analysis of tactile hierarchical patterns in 110 early‐blind children aged 6–8 to 16–18 years, as compared to 90 blindfolded sighted children, in a naming and haptic drawing task. The results revealed that regardless of visual status, young children predominantly produced local responses in both tasks, whereas the production of integrated responses emerged later. Development of local and global processing seems to proceed similarly in the two populations, but local processing continued to occur at high levels over a larger age range in the blind. The possibility of visual mediation is pointed out, as totally blind children tended to process information locally more often than blind children with minimal light perception.     

Visual Attention to Global and Local Stimulus Properties in 6‐Month‐Old Infants: Individual Differences and Event‐Related Potentials

Event‐related potentials (ERPs) were utilized in an investigation of 21 six‐month‐olds’ attention to and processing of global and local properties of hierarchical patterns. Overall, infants demonstrated an advantage for processing the overall configuration (i.e., global properties) of local features of hierarchical patterns; however, processing advantages were found to vary based on individual differences in look duration. Short‐looking infants showed differences in the negative central ERP component and the late slow wave (LSW) indicating greater attention to and discrimination of changes in global properties. Analysis of the LSW revealed that long‐looking infants discriminated changes in local features, but did not discriminate changes in global properties of visual stimuli. These findings indicate that short‐ and long‐looking infants utilize different approaches when processing hierarchical patterns.     

Infants' use of synchronized visual information to separate streams of speech

In 4 studies, 7.5-month-olds used synchronized visual-auditory correlations to separate a target speech stream when a distractor passage was presented at equal loudness. Infants succeeded in a segmentation task (using the head-turn preference procedure with video familiarization) when a video of the talker's face was synchronized with the target passage (Experiment 1, N = 30). Infants did not succeed in this task when an unsynchronized (Experiment 2, N = 30) or static (Experiment 3, N = 30) face was presented during familiarization. Infants also succeeded when viewing a synchronized oscilloscope pattern (Experiment 4, N = 26), suggesting that their ability to use visual information is related to domain-general sensitivities to any synchronized auditory-visual correspondence.     

Development of knowledge of visual-tactual affordances of substance

Infants of 12 months were familiarized in the dark with an object of either a hard or an elastic (spongy) substance. Following 60 sec of manipulation, a visual preference test was given with simultaneous presentation of 2 films of identical objects, 1 moving in a pattern characteristic of a rigid object and 1 moving in a pattern characteristic of an elastic object. Infants handled the 2 substances differently in an appropriate manner and looked preferentially with more and longer first looks to the type of substance familiarized. A replication of this experiment with familiarization in the light yielded comparable results. A third experiment with 1-month-old infants allowed them to mouth objects of either a hard or a soft substance for haptic familiarization and then tested looking preferences with real objects moving rigidly or deforming. These infants looked longer at the object moving in a manner characteristic of the novel substance. The results, together, suggest that quite young infants detect intermodal invariants specifying some substances and perceive the affordance of the substance.