Infants’ shifts of gaze from a central to a peripheral stimulus: a longitudinal study of development between 6 and 26 weeks

Gaze behavior in infancy associates with developmental outcome at the age of two years in early-onset epilepsies

PURPOSE

The neurodevelopmental outcome of infants with early-onset epilepsies varies widely, ranging from typical development to global developmental delay. Visual skills, which emerge during infancy, are crucial for the development of cognitive functions. The aim of this observational cohort study was to explore gaze behavior in infants with early-onset epilepsy and evaluate if eye tracking could support prognostication of their neurodevelopment.

METHODS

Fifty-one infants (22 females, mean seizure onset-age 5, SD ± 2, months) from a prospective epilepsy cohort underwent repeated eye tracking and Hammersmith Infantile/Neonatal Neurological examination (HINE/HNNE). Neurodevelopment at age two was categorized as typical development (mean Bayley [BSID-III] cognitive and language or Griffiths [GMDS-III] scales score ≥ 85) and developmental delay. At initial (age 3-10 months) and 12-month visit, we compared reliability of fixation, probability of gaze shifts and saccadic reaction times (SRTs) in a non-competitive SRT-task between developmental groups. Gaze behavior was also compared across etiologies, syndrome groups and between those with optimal versus suboptimal first HINE/HNNE.

RESULTS

Infants with typical developmental outcome (n = 23) had higher reliability of fixation (p = 0.007) and higher probability of gaze shifts (p = 0.012) at initial eye tracking than those with delay (n = 28). SRTs became faster during the follow-up but did not differ significantly between the developmental groups. Gaze behavior associated with epilepsy syndrome, etiology, and initial HINE/HNNE result.

CONCLUSIONS

Ability to fixate reliably and shift gaze soon after the epilepsy diagnosis is associated with developmental outcome in infants with early-onset epilepsy, suggesting that eye tracking could be useful as an additional prognostic tool.

The impact of rhythm on visual attention disengagement in newborns and 2-month-old infants

Rhythm entrains attention in both human and non-human animals. Here, the ontogenetic origins of this effect were investigated in newborns (Experiment 1; N = 30, 16 females) and 2-month-old infants (Experiment 2; N = 30, 17 females). Visuospatial attentional disengagement was tested in an overlap task where a static peripheral stimulus (S2) appeared while a central rhythmic, non-rhythmic or static stimulus (S1) remained visible on the screen. Results indicated a developmental pattern, with 2-month-olds, but not newborns, showing equally faster disengagement of fixation when S1 was static or rhythmic compared to non-rhythmic. Infants' preferential looking behaviour indicate that this difference in saccadic latencies was not due to stimulus salience (Experiment 3; N = 30, 18 females). Results point to the importance of the temporal structure of dynamic stimuli as a specific feature that modulates attentional disengagement at 2 months of age.

Genetic and environmental contributions to individual differences in visual attention and oculomotor control in early infancy

Infants differ in their level of eye movement control, which at the extreme could be linked to autism. We assessed eye movements in 450 twins (225 pairs, 57% monozygotic, 46% female, aged 5-6 months) using the gap-overlap eye-tracking task. Shorter latency in the gap condition was associated with having more parent-rated autistic traits at 2 years. Latency across the task's three conditions was primarily explained by one highly heritable latent factor likely representing individual differences in basic oculomotor efficiency and/or in visual information processing. Additionally, disengagement of attention was linked to unique genetic factors, suggesting that genetic factors involved in visual attention are different from those involved in basic visual information processing and oculomotor efficiency.

Coregistration of EEG and eye-tracking in infants and developing populations

Infants cannot be instructed where to look; therefore, infant researchers rely on observation of their participant's gaze to make inferences about their cognitive processes. They therefore started studying infant attention in the real world from early on. Developmental researchers were early adopters of methods combining observations of gaze and behaviour with electroencephalography (EEG) to study attention and other cognitive functions. However, the direct combination of eye-tracking methods and EEG to test infants is still rare, as it includes specific challenges. The current article reviews the development of co-registration research in infancy. It points out specific challenges of co-registration in infant research and suggests ways to overcome them. It ends with recommendations for implementing the co-registration of EEG and eye-tracking in infant research to maximise the benefits of the two measures and their combination and to orient on Open Science principles while doing so. In summary, this work shows that the co-registration of EEG and eye-tracking in infant research can be beneficial to studying natural and real-world behaviour despite its challenges.

Maximizing valid eye-tracking data in human and macaque infants by optimizing calibration and adjusting areas of interest

Remote eye tracking with automated corneal reflection provides insights into the emergence and development of cognitive, social, and emotional functions in human infants and non-human primates. However, because most eye-tracking systems were designed for use in human adults, the accuracy of eye-tracking data collected in other populations is unclear, as are potential approaches to minimize measurement error. For instance, data quality may differ across species or ages, which are necessary considerations for comparative and developmental studies. Here we examined how the calibration method and adjustments to areas of interest (AOIs) of the Tobii TX300 changed the mapping of fixations to AOIs in a cross-species longitudinal study. We tested humans (N = 119) at 2, 4, 6, 8, and 14 months of age and macaques (Macaca mulatta; N = 21) at 2 weeks, 3 weeks, and 6 months of age. In all groups, we found improvement in the proportion of AOI hits detected as the number of successful calibration points increased, suggesting calibration approaches with more points may be advantageous. Spatially enlarging and temporally prolonging AOIs increased the number of fixation-AOI mappings, suggesting improvements in capturing infants' gaze behaviors; however, these benefits varied across age groups and species, suggesting different parameters may be ideal, depending on the population studied. In sum, to maximize usable sessions and minimize measurement error, eye-tracking data collection and extraction approaches may need adjustments for the age groups and species studied. Doing so may make it easier to standardize and replicate eye-tracking research findings.

Visual competition attenuates emotion effects during overt attention shifts

Numerous different objects are simultaneously visible in a person's visual field, competing for attention. This competition has been shown to affect eye-movements and early neural responses toward stimuli, while the role of a stimulus' emotional meaning for mechanisms of overt attention shifts under competition is unclear. The current study combined EEG and eye-tracking to investigate effects of competition and emotional content on overt shifts of attention to human face stimuli. Competition prolonged the latency of the P1 component and of saccades, while faces showing emotional expressions elicited an early posterior negativity (EPN). Remarkably, the emotion-related modulation of the EPN was attenuated when two stimuli were competing for attention compared to non-competition. In contrast, no interaction effects of emotional expression and competition were observed on other event-related potentials. This finding indicates that competition can decelerate attention shifts in general and also diminish the emotion-driven attention capture, measured through the smaller effects of emotional expression on EPN amplitude. Reduction of the brain's responsiveness to emotional content in the presence of distractors contradicts models that postulate fully automatic processing of emotions.

The development of visual attention in early infancy: Insights from a free-viewing paradigm

Theories of visual attention suggest a cascading development of subfunctions such as alertness, spatial orientation, attention to object features, and endogenous control. Here, we aimed to track infants' visual developmental steps from a primarily exogenously to more endogenously controlled processing style during their first months of life. In this repeated measures study, 51 infants participated in seven fortnightly assessments at postterm ages of 4-16 weeks. Infants were presented with the same set of static and dynamic paired comparison stimuli in each assessment. Visual behavior was evaluated by a newly introduced scoring scheme. Our results confirmed the suggested visual developmental hierarchy and clearly demonstrated the suitability of our scoring scheme for documenting developmental changes in visual attention during early infancy. Besides the general ontogenetic course of development, we also discuss intra- and interindividual differences which may affect single assessments, and highlight the importance of repeated measurements for reliable evaluation of developmental changes.

Testing predictions of a neural process model of visual attention in infancy across competitive and non-competitive contexts

A key question in early development is how changes in neural systems give rise to changes in infants' behavior. We examine this question by testing predictions of a dynamic field (DF) model of infant spatial attention. We tested 5‐, 7‐, and 10‐month‐old infants in the Infant Orienting With Attention (IOWA) task containing the original non‐competitive cue conditions (when a central stimulus disappeared before a cue onset) and new competitive cue conditions (when a central stimulus remained visible throughout the trial). This allowed testing of five model predictions: (1) that orienting accuracy would be higher and (2) reaction times would be slower for all competitive conditions; (3) that all infants would be slower to orient in the competitive conditions, though (4) older infants would show the strongest competition costs; and (5) that reaction times would be particularly slow for un‐cued competitive conditions. Four of these five predictions were supported, and the remaining prediction was supported in part. We next examined fits of the model to the expanded task. New simulation results reveal close fits to the present findings after parameter modification. Critically, developmental parameters of the model were not altered, providing support for the DF model's account of neuro‐developmental change.

Quantification of gaze reaction time in infants with Pediatric Perimeter

Purpose

We quantified the eye/head (gaze) reaction time in infants to establish a normative database for the Pediatric Perimeter device. Additionally, we tested the hypothesis that gaze reaction time will reduce with age.

Methods

A cross-sectional study was conducted. Healthy infants between 3 to 10 months of age were recruited. Peripheral visual field stimuli (hemifield and quadrant stimuli) were presented in the Pediatric Perimeter device. Infant’s gaze to these stimuli was observed, documented in real time, and video recorded for offline analysis.

Results

A total of 121 infants were tested in three age group bins [3–5 months, n = 44; >5–7 months, n = 30 and >7–10 months, n = 47]. Overall, 3–5 months old had longer reaction time when compared to the older infants particularly for stimuli presented in the quadrants (Kruskal-Wallis, p<0.038). A significantly asymmetric difference (p = 0.025) in reaction time was observed between the upper (median = 820ms, IQR = 659-1093ms) and lower quadrants (median = 601ms, IQR = 540-1052ms) only for the 3–5 months old infants.

Conclusion

This study provides the normative gaze reaction time of healthy infants. With increase in age, there is reduction in reaction time and disappearance of reaction time asymmetry in quadrant stimuli. The longer reaction time for upward gaze could be due to delayed maturation of neural mechanisms and/or decreased visual attention.

Relation Between Event-Related Potential Latency and Saccade Latency in Overt Shifts of Attention

Controlled shifts of attention between competing stimuli are crucial for effective everyday visual behaviour. While these typically involve overt shifts of fixation, many past studies used covert attention shifts in which fixation is unchanged, meaning that some response components may result from the inhibition of eye movements. In this study, the neural events in the human brain when making overt shifts of attention are studied through the combination of event-related potential recording with simultaneous eye tracking. Fixation shifts under competition (central target remains visible when a peripheral target appears) were compared with noncompetition (central target disappears). A longer latency for competition compared with noncompetition, which is found in the saccadic response, is already present in the early occipital positivity when a single target is presented for the fixation shift. These results indicate that the requirement to disengage from a current target affects the time course of neural processing at an early level. However, the relation is more complex when the participant is required to choose which of two targets to fixate.

Fixations and Fixation Shifts in Own-Race and Other-Race Face Pairs at Three, Six and Nine Months

Caucasian infants were presented 15 pairs of Caucasian own-race faces and 15 pairs of African other-race faces. The infants were assessed longitudinally at ages three, six and nine months. Two measures were obtained from the infants' eye-movements: (1) the length of fixations on either stimulus of a pair presented for 5.5 s (fixation duration) and (2) the amount of fixation shifts between the two stimuli (shift frequency). The study analyzes the changes in both measures with age and across the within-race face pair presentations. Despite general age-related improvements reflected in shorter fixation durations and a higher shift frequency, the results reveal differences between African face pairs and Caucasian face pairs at six and nine months. During the first trials (spontaneous looking behavior) the infants shift more often between the Caucasian own-race faces than between the African other-race faces. The fixation durations, however, which are typically of focus in Visual Pair Preference Tasks, do not differ significantly between the face races. The results are interpreted in terms of processing differences for own-race faces and the emerging Other-Race-Effect by six months of age. Furthermore, the usability of fixation duration as the only measure in the pair comparison setting is discussed.

Top-down contextual knowledge guides visual attention in infancy

The visual context in which an object or face resides can provide useful top-down information for guiding attention orienting, object recognition, and visual search. Although infants have demonstrated sensitivity to covariation in spatial arrays, it is presently unclear whether they can use rapidly acquired contextual knowledge to guide attention during visual search. In this eye-tracking experiment, 6- and 10-month-old infants searched for a target face hidden among colorful distracter shapes. Targets appeared in Old or New visual contexts, depending on whether the visual search arrays (defined by the spatial configuration, shape and color of component items in the search display) were repeated or newly generated throughout the experiment. Targets in Old contexts appeared in the same location within the same configuration, such that context covaried with target location. Both 6- and 10-month-olds successfully distinguished between Old and New contexts, exhibiting faster search times, fewer looks at distracters, and more anticipation of targets when contexts repeated. This initial demonstration of contextual cueing effects in infants indicates that they can use top-down information to facilitate orienting during memory-guided visual search.

The Effect of Stimulus Size and Eccentricity on Attention Shift Latencies

The ability to shift attention between relevant stimuli is crucial in everyday life and allows us to focus on relevant events. It develops during early childhood and is often impaired in clinical populations, as can be investigated in the fixation shift paradigm and the gap-overlap paradigm. Different tests use stimuli of different sizes presented at different eccentricities, making it difficult to compare them. This study systematically investigates the effect of eccentricity and target size on refixation latencies towards target stimuli. Eccentricity and target size affected attention shift latencies with greatest latencies to big targets that were presented at a small eccentricity. Slowed responses to large parafoveal targets are in line with the idea that specific areas in the superior colliculus can lead to inhibition of eye movements. Findings suggest that the two different paradigms are generally comparable, as long as the target is scaled in proportion to the eccentricity.

Modeling Infant i's Look on Trial t: Race-Face Preference Depends on i's Looking Style

When employing between-infant designs young infants' looking style is related to their development: Short looking (SL) infants are cognitively accelerated over their long looking (LL) peers. In fact, looking style is a within-infant variable, and depends on infant i's look distribution over trials. For the paired array setting, a model is provided which specifies the probability, π_i ∈ [0, 1], that i is SL. The model is employed in a face preference study; 74 Caucasian infants were longitudinally assessed at 3, 6, and 9 months. Each i viewed same race (Caucasian) vs. other race (African) faces. Infants become SL with development, but there are huge individual differences in rate of change over age. Three month LL infants, π^i<1/2, preferred other race faces. SL infants, π^i>1/2, preferring same race faces at 3, and other race faces at 6 and 9 months. Looking style changes precede and may control changes in face preference. Ignoring looking style can be misleading: Without considering looking style, 3 month infants show no face preference.

Disentangling the mechanisms underlying infant fixation durations in scene perception: A computational account

The goal of this article is to investigate the unexplored mechanisms underlying the development of saccadic control in infancy by determining the generalizability and potential limitations of extending the CRISP theoretical framework and computational model of fixation durations (FDs) in adult scene-viewing to infants. The CRISP model was used to investigate the underlying mechanisms modulating FDs in 6-month-olds by applying the model to empirical eye-movement data gathered from groups of infants and adults during free-viewing of naturalistic and semi-naturalistic videos. Participants also performed a gap-overlap task to measure their disengagement abilities. Results confirmed the CRISP model's applicability to infant data. Specifically, model simulations support the view that infant saccade programming is completed in two stages: an initial labile stage, followed by a non-labile stage. Moreover, results from the empirical data and simulation studies highlighted the influence of the material viewed on the FD distributions in infants and adults, as well as the impact that the developmental state of the oculomotor system can have on saccade programming and execution at 6months. The present work suggests that infant FDs reflect on-line perceptual and cognitive activity in a similar way to adults, but that the individual developmental state of the oculomotor system affects this relationship at 6months. Furthermore, computational modeling filled the gaps of psychophysical studies and allowed the effects of these two factors on FDs to be simulated in infant data providing greater insights into the development of oculomotor and attentional control than can be gained from behavioral results alone.

Introduction of the Utrecht Tasks for Attention in Toddlers Using Eye Tracking (UTATE): A Pilot Study

Attention capacities underlie everyday functioning from an early age onwards. Little is known about attentional processes at toddler age. A feasible assessment of attention capacities at toddler age is needed to allow further study of attention development. In this study, a test battery is piloted that consists of four tasks which intend to measure the attention systems orienting, alerting, and executive attention: the Utrecht Tasks of Attention in Toddlers using Eye tracking [UTATE]. The UTATE assesses looking behavior that may reflect visual attention capacities, by using eye-tracking methods. This UTATE was studied in 16 Dutch 18-month-old toddlers. Results showed that the instrument is feasible and generates good quality data. A first indication of sufficient reliability was found for most of the variables. It is concluded that the UTATE can be used in further studies. Further evaluation of the reliability and validity of the instrument in larger samples is worthwhile.

Factor Structure of Attention Capacities Measured With Eye-Tracking Tasks in 18-Month-Old Toddlers

OBJECTIVE

Attention capacities are critical for adaptive functioning and development. Reliable assessment measures are needed for the study of attention capacities in early childhood. In the current study, we investigated the factor structure of the Utrecht Tasks of Attention in Toddlers Using Eye-tracking (UTATE) test battery that assesses attention capacities in 18-month-old toddlers with eye-tracking techniques.

METHOD

The factor structure of 13 measures of attention capacities, based on four eye-tracking tasks, was investigated in a sample of 95 healthy toddlers (18 months of age) using confirmatory factor analysis.

RESULTS

Results showed that a three-factor model best fitted the data. The latent constructs reflected an orienting, alerting, and executive attention system.

CONCLUSION

This study showed support for a three-factor model of attention capacities in 18-month-old toddlers. Further study is needed to investigate whether the model can also be used with children at risk of attention problems.

The attentive brain: insights from developmental cognitive neuroscience

Visual attention functions as a filter to select environmental information for learning and memory, making it the first step in the eventual cascade of thought and action systems. Here, we review studies of typical and atypical visual attention development and explain how they offer insights into the mechanisms of adult visual attention. We detail interactions between visual processing and visual attention, as well as the contribution of visual attention to memory. Finally, we discuss genetic mechanisms underlying attention disorders and how attention may be modified by training.

Face Orientation and Motion Differently Affect the Deployment of Visual Attention in Newborns and 4-Month-Old Infants

Orienting visual attention allows us to properly select relevant visual information from a noisy environment. Despite extensive investigation of the orienting of visual attention in infancy, it is unknown whether and how stimulus characteristics modulate the deployment of attention from birth to 4 months of age, a period in which the efficiency in orienting of attention improves dramatically. The aim of the present study was to compare 4-month-old infants' and newborns' ability to orient attention from central to peripheral stimuli that have the same or different attributes. In Experiment 1, all the stimuli were dynamic and the only attribute of the central and peripheral stimuli to be manipulated was face orientation. In Experiment 2, both face orientation and motion of the central and peripheral stimuli were contrasted. The number of valid trials and saccadic latency were measured at both ages. Our results demonstrated that the deployment of attention is mainly influenced by motion at birth, while it is also influenced by face orientation at 4-month of age. These findings provide insight into the development of the orienting visual attention in the first few months of life and suggest that maturation may be not the only factor that determines the developmental change in orienting visual attention from birth to 4 months.

Associations between developmental trajectories of movement variety and visual attention in fullterm and preterm infants during the first six months postterm

BACKGROUND

During early infancy major developmental changes, both in the variety of body movements and in visual attention, help the infant to explore its surroundings. Both behaviours depend on a gradual shift from subcortical to cortical functioning.

AIMS

First, to determine whether preterms reach mature levels of movement variety (the number of different movement patterns) and visual attention earlier than fullterms. Second, to determine whether individual developmental trajectories of movement variety and visual attention were associated. Finally, we compared the associations of developmental trajectories between fullterm and preterm infants.

STUDY DESIGN

In this longitudinal study, 20 fullterm and 9 low-risk preterm infants performed a visual disengagement task every four weeks from six weeks until six months postterm. For each infant we drew up developmental trajectories for movement variety, and for frequencies and latencies of looks. We analyzed the developmental trajectories by means of general linear model (GLM) repeated measures and Monte Carlo analyses.

RESULTS

In comparison to fullterms, preterm infants showed a similar increase in movement variety over time (F(4,108)=0.27; partial eta(2)=0.01; P=.90). Visual attention reached mature levels four weeks earlier than movement variety. This effect was stronger in fullterm infants. Neither in fullterm nor in preterm infants did we find an association between the developmental trajectories of movement variety and visual attention. P values ranged from .37 to .99.

CONCLUSIONS

During the first 6 months postterm, movement variety and visual attention developed independently. Temporarily, preterm exposure to the extrauterine environment led to shorter latencies of looks but it did not affect developmental trajectories of frequencies of looks and movement variety.

Early visual attention in preterm and fullterm infants in relation to cognitive and motor outcomes at school age: an exploratory study

OBJECTIVE

Preterm infants are exposed to the visual environment earlier than fullterm infants, but whether early exposure affects later development is unclear. Our aim was to investigate whether the development of visual disengagement capacity during the first 6 months postterm was associated with cognitive and motor outcomes at school age, and whether associations differed between fullterms and low-risk preterms.

METHOD

Seventeen fullterms and ten low-risk preterms were tested in a gaze shifting task every 4 weeks until 6 months postterm. The longitudinal data were converted into single continuous variables by fitting the data with an S-shaped curve (frequencies of looks) or an inverse model (latencies of looks). Neuropsychological test results at school age were converted into composite z scores. We then performed linear regression analyses for each functional domain at school age with the variables measuring infant visual attention as separate predictors and adjusting for maternal level of education and group (fullterms versus preterms). We included an interaction term, visual attention*group, to determine whether predictive relations differed between fullterms and preterms.

RESULTS

A slower development of disengagement predicted poorer performance on attention, motor skills, and handwriting, irrespective of fullterm or preterm birth. Predictive relationships differed marginally between fullterms and preterms for inhibitory attentional control (P = 0.054) and comprehensive reading (P = 0.064).

CONCLUSION

This exploratory study yielded no indications of a clear advantage or disadvantage of the extra visual exposure in healthy preterm infants. We tentatively conclude that additional visual exposure does not interfere with the ongoing development of neuronal networks during this vulnerable period of brain development.

Peripheral Stimulus Localization by Infants of Moving Stimuli on Complex Backgrounds

This study examined the effect of attention in young infants on the saccadic localization of dynamic peripheral stimuli presented on complex and interesting backgrounds. Infants at 14, 20, and 26 weeks of age were presented with scenes from a Sesame Street movie until fixation on a moving character occurred and then presented with a second segment in the scene in which the character movement occurred in a new location. Localization of the moving character in the new location was faster when the infant was engaged in attention than when inattentive, for scenes in which the character moved from one location to another, or scenes in which the character stopped moving and characters in new locations began moving. However, localization of the character was slower during attention when the first character disappeared and a different character appeared in a new location. We also found a decrease in the linear component of the main sequence in the saccade characteristics over the three testing ages, and attention affected the main sequence for infants at the two oldest ages. These results partially replicate prior findings showing that attention to a focal stimulus affects localization of peripheral stimuli, but suggest that the nature of the stimuli being localized modifies the role of attention in affecting eye movements to peripheral stimuli.

Reaching experience increases face preference in 3-month-old infants

The developing infant learns about the physical and the social world by engaging with objects and with people. In the study reported here, we investigated the relationship between infants' interactions with the physical and the social world. Three-month-old infants were trained for 2 weeks and experienced either actively manipulating objects themselves or passively having objects touched to their hands. Following active or passive experiences, spontaneous orienting towards faces and objects was compared between the trained groups and untrained 3- and 5-month-olds. It is known that the onset of reaching behavior increases infants' interest in objects. However, we report that active, self-produced reaching experiences also increase infants' spontaneous orienting towards faces, while passive experiences do not affect orienting behavior. Regression analyses provide evidence for a link between manual engagement and the development of orienting towards faces. Implications of orienting towards faces for the development of triadic interactions, joint attention, and social cognition in general are discussed.

Quantitative aspects of the early motor repertoire in preterm infants: do they predict minor neurological dysfunction at school age?

BACKGROUND

Qualitative aspects of the motor repertoire, at 11-16 weeks post-term are predictive for minor neurological dysfunction (MND) at 7 to 11 years of age. Predictive value of quantitative aspects is unknown so far.

AIM

To investigate whether quantitative aspects of the motor repertoire between 6 and 24 weeks post-term also have predictive value for neurological outcome at 7 to 11 years of age.

STUDY DESIGN

Prospective cohort study.

SUBJECTS

Preterm infants from whom several quantitative aspects of the motor repertoire were assessed between 6 and 24 weeks post-term.

OUTCOME MEASURES

Neurological outcome at 7-11 years of age was assessed according to Touwens' neurological examination. Children were classified as neurologically normal, or as having complex MND or cerebral palsy (CP).

RESULTS

Eighty-two children were included. At 7 to 11 years of age 15 children (18%) had developed CP, 49 (60%) were neurologically normal, and 18 (22%) had MND. Multiple logistic regression analysis showed that, when the qualitative aspects of the motor repertoire known to predict neurological outcome were taken into account, only the asymmetric tonic neck (ATN) posture provided additional predictive value. In case of normal fidgety movements (FMs) accompanied by an abnormal concurrent motor repertoire, the presence of an obligatory ATN increased the risk for developing complex MND to 75%; absence of an obligatory ATN reduced the risk to 15% (p<0.05).

CONCLUSIONS

Quantitative aspects of the motor repertoire at 11-16 weeks post-term, in particular the presence of an obligatory ATN posture, contribute to the prediction of neurological outcome at 7 to 11 years of age.

Development of infants' attention to faces during the first year

In simple tests of preference, infants as young as newborns prefer faces and face-like stimuli over distractors. Little is known, however, about the development of attention to faces in complex scenes. We recorded eye-movements of 3-, 6-, and 9-month-old infants and adults during free-viewing of clips from A Charlie Brown Christmas (an animated film). The tendency to look at faces increased with age. Using novel computational tools, we found that 3-month-olds were less consistent (across individuals) in where they looked than were older infants. Moreover, younger infants' fixations were best predicted by low-level image salience, rather than the locations of faces. Between 3 and 9 months of age, infants gradually focused their attention on faces. We discuss several possible interpretations of this shift in terms of social development, cross-modal integration, and attentional/executive control.

Effects of preterm experience on the developing visual system: a longitudinal study of shifts of attention and gaze in early infancy

Several studies on visual development support the notion that healthy, low-risk preterm infants benefit from their early exposure to the visual world. It has been suggested, however, that mainly early developing sensory and motor processes are enhanced as a result of visual experience and early exercise, whereas later maturing processes might not. This study investigates whether preterm infants' visual and attentional development is accelerated as a consequence of their early visual experience and whether early and later maturing processes are affected differently. Preterm and full-term infants' performance on a gaze and attention shifting task was examined during the first six months of life. Until about 16 weeks post- term, preterm infants were faster in disengaging and shifting their attention and gaze from a stimulus in their central visual field to the periphery, whereas no difference was found for simple gaze shifts without disengagement. This finding is in contrast to earlier accounts that only early developing mechanisms might be advanced as a result of additional visual experience, whereas later developing cortical processes might depend mainly on preprogrammed maturation processes. However, it is consistent with a number of findings on visual, motor, and speech development, which have indicated accelerated cortical functioning in healthy preterm infants before.

The early development of visual attention and its implications for social and cognitive development

Looking behavior plays a crucial role in the daily life of an infant and forms the basis for cognitive and social development. The infant's visual attentional systems undergo rapid development during the first few months of life. During the last decennia, the study of visual attentional development in infants has received increasing interest. Several reliable measures to investigate the early development of attentional processes have been developed, and currently a number of new methods are giving fresh impetus to the field. Research on overt and covert as well as exogenously and endogenously controlled attention shifts is presented. The development of gaze shifts to peripheral targets, covert attention, and visual scanning behavior is treated. Whereas most attentional mechanisms in very young infants are thought to be mediated mainly by subcortical structures, cortical mechanisms become increasingly more functional throughout the first months. Different accounts of the neurophysiological underpinnings of attentional processes and their developmental changes are discussed. Finally, a number of studies investigating the implications of attentional development for early cognitive and social development are presented.

Gaze following: why (not) learn it?

We propose a computational model of the emergence of gaze following skills in infant-caregiver interactions. The model is based on the idea that infants learn that monitoring their caregiver's direction of gaze allows them to predict the locations of interesting objects or events in their environment (Moore & Corkum, 1994). Elaborating on this theory, we demonstrate that a specific Basic Set of structures and mechanisms is sufficient for gaze following to emerge. This Basic Set includes the infant's perceptual skills and preferences, habituation and reward-driven learning, and a structured social environment featuring a caregiver who tends to look at things the infant will find interesting. We review evidence that all elements of the Basic Set are established well before the relevant gaze following skills emerge. We evaluate the model in a series of simulations and show that it can account for typical development. We also demonstrate that plausible alterations of model parameters, motivated by findings on two different developmental disorders - autism and Williams syndrome - produce delays or deficits in the emergence of gaze following. The model makes a number of testable predictions. In addition, it opens a new perspective for theorizing about cross-species differences in gaze following.

Associations between the developmental trajectories of visual scanning and disengagement of attention in infants

The relation between the developmental trajectories of visual scanning and disengagement of attention and gaze were examined throughout early infancy. A sample of 10 infants carried out a scanning and a disengagement task with the same visual stimuli six times between 6 and 26 weeks of age. Frequency and latency measures were analyzed using multivariate multilevel models and Monte Carlo analyses. The results suggest that the ability to scan a face or an abstract stimulus evolves slightly earlier than the ability to shift gaze to a newly appeared target in the periphery. This is consistent with the account that the parvocellular stream becomes functional slightly before the magnocellular stream. The study revealed no indications of a positive association between the development of scanning and disengagement on the level of the individual infant. Scanning and disengagement change scores contrasted more with one another than could be expected on the basis of chance. This implies that the magnocellular and the parvocellular stream develop rather independently up to the age of 26 weeks.

Infants' emerging ability to represent occluded object motion

The emerging ability to represent an oscillating moving object over occlusions was studied in 7-21-week-old infants. The object moved at 0.25 Hz and was either occluded at the center of the trajectory (for 0.3 s) or at one turning point (for 0.7 s). Each trial lasted for 20 s. Both eye and head movements were measured. By using two kinds of motion, sinusoidal (varying velocity) and triangular (constant velocity), infants' ability to take velocity change into account when predicting the reappearance of the moving object was tested. Over the age period studied, performance at the central occluder progressed from almost total ignorance of what happened to consistent predictive behavior. From around 12 weeks of age, infants began to form representations of the moving object that persisted over temporary occlusions. At around 5 months of age these representations began to incorporate the dynamics of the represented motion. Strong learning effects were obtained over single trials, but there was no evidence of retention between trials. The individual differences were profound.

Natural imitation induced by joint attention in Japanese monkeys

To examine whether joint attention enables Japanese monkeys to imitate human actions, we presented an oral action and manual actions directed towards targets to three monkeys who had joint attention through communicative eye-gaze and pointing gestures and to one monkey who had incomplete joint attention and who had acquired imperative pointing but not the use of eye-gaze gestures. Two of the monkeys who were already capable of joint attention were also able to imitate naturally, while the monkey who did not previously show joint attention was not able to imitate until acquiring joint attention capacity. We suggest that joint attention induces natural imitation during interaction between different species--in this case, between monkeys and humans--while individuals not showing joint attention but only attention to a target or movement are only able to follow motion. The monkey may be endowed by nature with motion-following capacity. We speculate that motion-following capacity is developed and controlled through joint attention, and is connected with natural imitation.

Infant visual recognition memory: independent contributions of speed and attention

Relations between infant visual recognition memory and later cognition have fueled interest in identifying the underlying cognitive components of this important infant ability. The present large-scale study examined three promising factors in this regard--processing speed, short-term memory capacity, and attention. Two of these factors, attention and processing speed (but, surprisingly, not short-term memory capacity), were related to visual recognition memory: Infants who showed better attention (shorter looks and more shifts) and faster processing had better recognition memory. The contributions of attention and processing speed were independent of one another and were similar at all ages studied--5, 7, and 12 months. Taken together, attention and speed accounted for 6%-9% of the variance in visual recognition memory, leaving a considerable, but not unexpected, portion of the variance unexplained.

Peripheral Stimulus Localization by 5- to 14-Week-Old Infants During Phases of Attention

This study examined the effect of attention in young infants on the saccadic localization of peripheral stimuli. Infants ranging in age from 5 to 14 weeks were tested using a peripheral stimulus detection paradigm. The presence of a central fixation stimulus decreased detection probability, particularly if attention was engaged with the central stimulus. Peripheral stimulus localization usually was accomplished with a single eye movement. When localization was accomplished by multiple eye movements, corrective saccades occurred most frequently and fixed-amplitude hypometric saccades occurred less frequently. A decrease in the slope of the linear component of the main sequence was found from 5 to 11 weeks of age, and this decrease was independent of attention.

A longitudinal study of the development of shifts of gaze to a peripheral stimulus in preterm infants with transient periventricular echogenicity

Shifts of gaze to peripheral targets were studied longitudinally, between 6 and 26 weeks corrected age, in full-term and very preterm infants with transient periventricular echogenicity (PVE). Before 10 weeks, simple shifts of gaze were faster and more frequent in preterms with PVE<14 days than in full-terms, suggesting these preterms profited from additional early visual experience. After 16 weeks, there were subtle differences between full- and preterm infants in the development of shifts of gaze requiring disengagement. The differences suggest that, after disengagement had become established, its fine-tuning occurred more slowly in the preterms. Slower fine-tuning of disengagement was not associated with duration of PVE, since it was more marked in preterms with PVE<14 days than in preterms with PVE> or =14 days. The differences in performance between full- and preterm infants were small. However, even small differences may affect the efficiency of visually guided behaviors.