Infants' representations of three-dimensional occluded objects

Infants' ability to represent objects has received significant attention from the developmental research community. With the advent of eye-tracking technology, detailed analysis of infants' looking patterns during object occlusion have revealed much about the nature of infants' representations. The current study continues this research by analyzing infants' looking patterns in a novel manner and by comparing infants' looking at a simple display in which a single three-dimensional (3D) object moves along a continuous trajectory to a more complex display in which two 3D objects undergo trajectories that are interrupted behind an occluder. Six-month-old infants saw an occlusion sequence in which a ball moved along a linear path, disappeared behind a rectangular screen, and then a ball (ball-ball event) or a box (ball-box event) emerged at the other edge. An eye-tracking system recorded infants' eye-movements during the event sequence. Results from examination of infants' attention to the occluder indicate that during the occlusion interval infants looked longer to the side of the occluder behind which the moving occluded object was located, shifting gaze from one side of the occluder to the other as the object(s) moved behind the screen. Furthermore, when events included two objects, infants attended to the spatiotemporal coordinates of the objects longer than when a single object was involved. These results provide clear evidence that infants' visual tracking is different in response to a one-object display than to a two-object display. Furthermore, this finding suggests that infants may require more focused attention to the hidden position of objects in more complex multiple-object displays and provides additional evidence that infants represent the spatial location of moving occluded objects.     

Effects of gesture and target on 12- and 18-month-olds' joint visual attention to objects in front of or behind them

Factors affecting joint visual attention in 12- and 18-month-olds were investigated. In Experiment 1 infants responded to 1 of 3 parental gestures: looking, looking and pointing, or looking, pointing, and verbalizing. Target objects were either identical to or distinctive from distractor objects. Targets were in front of or behind the infant to test G. E. Butterworth's (1991b) hypothesis that 12-month-olds do not follow gaze to objects behind them. Pointing elicited more episodes of joint visual attention than looking alone. Distinctive targets elicited more episodes of joint visual attention than identical targets. Although infants most reliably followed gestures to targets in front of them, even 12-month-olds followed gestures to targets behind them. In Experiment 2 parents were rotated so that the magnitude of their head turns to fixate front and back targets was equivalent. Infants looked more at front than at back targets, but there was also an effect of magnitude of head turn. Infants' relative neglect of back targets is partly due to the "size" of adult's gesture.     

The effect of positive emotion on infants' gaze shift

Infants often voluntarily glance at their social partner during their toy play, disengaging their gaze from a toy and selecting a caregiver as their new looking target. This study posed two research questions: Do positive emotions disengage infants' gaze from their point of fixation, and do positive emotions facilitate the selection of the caregiver as their next looking target? The rate of gaze shifts was calculated for neutral and positive emotional states during their toy play. Across all ages, infants exhibited more disengagement from their point of fixation in the positive state than in the neutral one. However, 6- and 9-month-old infants revealed no difference in selecting a caregiver or a physical object as their next looking target in the positive state, but 12-month-olds increased gazing at caregivers in the positive state. These results were discussed with regard to the role of positive emotions on the development of infants' initiating joint attention.     

Some Beginnings of Word Comprehension in 6-Month-Olds

Previous studies of infants' comprehension of words estimated the onset of this ability at 9 months or later. However, these estimates were based on responses to names of relatively immobile, familiar objects. Comprehension of names referring to salient, animated figures (e.g., one's parents) may begin even earlier. In a test of this possibility, 6-month-olds were shown side-by-side videos of their parents while listening to the words "mommy" and "daddy." The infants looked significantly more at the video of the named parent. A second experiment revealed that infants do not associate these words with men and women in general. Infants shown videos of unfamiliar parents did not adjust their looking patterns in response to "mommy" and "daddy."     

The development of emotional face and eye gaze processing

Recent research has demonstrated that infants' attention towards novel objects is affected by an adult's emotional expression and eye gaze toward the object. The current event-related potential (ERP) study investigated how infants at 3, 6, and 9 months of age process fearful compared to neutral faces looking toward objects or averting gaze away from objects. Furthermore, we examined how the processing of novel objects is affected by gaze direction and emotional expression. We hypothesized that an adult's fearful expression should be particularly salient when it is directed toward a referent in the environment. Furthermore, responses to objects should be increased if the face previously expressed fear toward the object. Three-month-olds did not show differential neural responses to fearful vs. neutral faces regardless of gaze direction. Six-month-olds showed an enhanced negative central (Nc) component for fearful relative to neutral faces looking toward objects, but not when eye gaze was averted away from the objects. Furthermore, 6-month-olds showed an enhanced Nc for objects that had been gaze-cued by a fearful compared to a neutral face. Nine-month-olds showed an enhanced Nc for fearful relative to neutral faces in both eye gaze conditions and showed an enhanced Nc for objects that had been gaze-cued by a neutral face. The findings are discussed in the context of social cognitive and brain development.     

Nine-month-olds’ shared visual attention as a function of gesture and object location

Two factors hypothesized to affect shared visual attention in 9-month-olds were investigated in two experiments. In Experiment 1, we examined the effects of different attention-directing actions (looking, looking and pointing, and looking, pointing and verbalizing) on 9-month-olds’ engagement in shared visual attention. In Experiment 1 we also varied target object locations (i.e., in front, behind, or peripheral to the infant) to test whether 9-month-olds can follow an adult’s gesture past a nearby object to a more distal target. Infants followed more elaborate parental gestures to targets within their visual field. They also ignored nearby objects to follow adults’ attention to a peripheral target, but not to targets behind them. In Experiment 2, we rotated the parent 90° from the infant’s midline to equate the size of the parents’ head turns to targets within as well as outside the infants’ visual field. This manipulation significantly increased infants’ looking to target objects behind them, however, the frequency of such looks did not exceed chance. The results of these two experiments are consistent with perceptual and social experience accounts of shared visual attention.     

Reducing infant immunization distress through distraction.

Infant procedural distress is largely understudied, and there is a dearth of empirically supported interventions in the child health psychology literature. This study examined nurse-directed distraction for reducing infant immunization distress. Ninety infants and their parents were randomly assigned to a distraction condition (i.e., nurses used stimuli to divert infants' attention) or a typical care condition. Outcome measures were an observational scale, parent and nurse ratings, and infant heart rate. Results indicated that infants engaged in distraction and that distraction reduced their behavioral distress; however, ratings and heart rate were inconclusive. Analyses of procedural phases indicated that infants exhibited elevated distress immediately prior to and during an injection, but this distress was fleeting.     

婴儿共同注意能力的发展

本研究采用严格的实验室测验法,从年龄趋势、学习能力、性别差异三方面考察了8～11个月婴儿共同注意能力的发展。结果表明：1）婴儿的共同注意力在8～11个月间逐步提高,9个月左右出现显著的发展性变化,但1岁以前,该能力的发展水平都较低;2）就共同注意而言,婴儿具有从练习经验中学习的可能性,且学习能力存在年龄差异,8个月的婴儿基本不能从练习中受益,而8个月以上的其他三组婴儿在练习后共同注意水平都有不同程度的提高;3）总体而言,女婴共同注意能力的发展水平显著地高于男婴。     

Twelve-month-olds point to share attention and interest

Infants point for various motives. Classically, one such motive is declarative, to share attention and interest with adults to events. Recently, some researchers have questioned whether infants have this motivation. In the current study, an adult reacted to 12-month-olds' pointing in different ways, and infants' responses were observed. Results showed that when the adult shared attention and interest (i.e alternated gaze and emoted), infants pointed more frequently across trials and tended to prolong each point--presumably to prolong the satisfying interaction. However, when the adult emoted to the infant alone or looked only to the event, infants pointed less across trials and repeated points more within trials--presumably in an attempt to establish joint attention. Results suggest that 12-month-olds point declaratively and understand that others have psychological states that can be directed and shared.     

Head and eye movements affect object processing in 4‐month‐old infants more than an artificial orientation cue

This study investigates the effects of attention‐guiding stimuli on 4‐month‐old infants' object processing. In the human head condition, infants saw a person turning her head and eye gaze towards or away from objects. When presented with the objects again, infants showed increased attention in terms of longer looking time measured by eye tracking and an increased Nc amplitude measured by event‐related potentials (ERP) for the previously uncued objects versus the cued objects. This suggests that the uncued objects were previously processed less effectively and appeared more novel to the infants. In a second condition, a car instead of a human head turned towards or away from objects. Eye‐tracking results did not reveal any significant difference in infants' looking time. ERPs indicated only a marginally significant effect in late slow‐wave activity associated with memory encoding for the uncued objects. We conclude that human head orientation and gaze direction affect infants' object‐directed attention, whereas movement and orientation of a car have only limited influence on infants' object processing.     

Dynamic emotional messages differentially affect 6-month-old infants’ attention to eyes and gaze cues

Infants often experience interactions in which caregivers use dynamic messages to convey their affective and communicative intent. These dynamic emotional messages may shape the development of emotion discrimination skills and shared attention by influencing infants’ attention to internal facial features and their responses to eye gaze cues. However, past research examining infants’ responses to emotional faces has predominantly focused on classic, stereotyped expressions (e.g., happy, sad, angry) that may not reflect the variability that infants experience in their daily interactions. The present study therefore examined forty-two 6-month-old infants’ attention to eyes vs. mouth and gaze cueing responses across multiple dynamic emotional messages that are common to infant-directed interactions. Overall, infants looked more to the eyes during messages with negative affect, but this increased attention to the eyes during these message conditions did not directly facilitate gaze cueing. Infants instead showed reliable gaze cueing only after messages with positive and neutral affect. We additionally observed gender differences in infants’ attention to internal face features and subsequent gaze cueing responses. Female infants spent more time looking at the eyes during the dynamic emotional messages and showed increased initial orienting and longer looking to gaze-cued objects following positive messages, whereas male infants showed these gaze cueing effects following neutral messages. These results suggest that variability in caregivers' communication can shape infants’ attention to and processing of emotion and gaze information.     

Infant sustained attention but not joint attention to objects at 9 months predicts vocabulary at 12 and 15 months

Vocabulary differences early in development are highly predictive of later language learning as well as achievement in school. Early word learning emerges in the context of tightly coupled social interactions between the early learner and a mature partner. In the present study, we develop and apply a novel paradigm—dual head‐mounted eye tracking—to record momentary gaze data from both parents and infants during free‐flowing toy‐play contexts. With fine‐grained sequential patterns extracted from continuous gaze streams, we objectively measure both joint attention and sustained attention as parents and 9‐month‐old infants played with objects and as parents named objects during play. We show that both joint attention and infant sustained attention predicted vocabulary sizes at 12 and 15 months, but infant sustained attention in the context of joint attention, not joint attention itself, is the stronger unique predictor of later vocabulary size. Joint attention may predict word learning because joint attention supports infant attention to the named object.     

Action production influences 12-month-old infants' attention to others' actions

Recent work implicates a link between action control systems and action understanding. In this study, we investigated the role of the motor system in the development of visual anticipation of others' actions. Twelve-month-olds engaged in behavioral and observation tasks. Containment activity, infants' spontaneous engagement in producing containment actions; and gaze latency, how quickly they shifted gaze to the goal object of another's containment actions, were measured. Findings revealed a positive relationship: infants who received the behavior task first evidenced a strong correlation between their own actions and their subsequent gaze latency of another's actions. Learning over the course of trials was not evident. These findings demonstrate a direct influence of the motor system on online visual attention to others' actions early in development.     

Self-experience as a mechanism for learning about others: a training study in social cognition

Using a gaze-following task, the authors assessed whether self-experience with the view-obstructing properties of blindfolds influenced infants' understanding of this effect in others. In Experiment 1, 12-month-olds provided with blindfold self-experience behaved as though they understood that a person wearing a blindfold cannot see. When a blindfolded adult turned to face an object, these infants gaze followed significantly less than control infants who had either (a) seen and felt the blindfold but whose view had not been obstructed by it or (b) experienced a windowed blindfold through which they could see. In Experiment 2, 18-month-olds experienced either (a) a trick blindfold that looked opaque but could be seen through, (b) an opaque blindfold, or (c) baseline familiarization. Infants receiving trick-blindfold experience now followed a blindfolded adult's gaze significantly more than controls. The authors propose 3 mechanisms underlying infants' capacity to use self-experience as a framework for understanding the visual perception of others.     

Infants' tracking of objects and collections

Recent research suggests that infants' understanding of the physical world is more complex and adult-like than previously believed. One of the most impressive discoveries has been infants' ability to reason about medium-sized, material objects. They are able to individuate objects in a scene, and to enumerate and reason about them. This article reports a series of experiments investigating 8-month-old infants' ability to reason about collections of objects. Experiment 1 shows a sharp contrast between infants' understanding of single objects versus collections. While infants detected the discontinuous ('Magical') disappearance of a single object, they did not detect the Magical Disappearance of a non-cohesive pile of objects. Experiments 2-4 found that infants' difficulty remained even when the distinct identity of each object in the collection was emphasized, but could be overcome if infants (a) first saw the individual objects clearly separated from each other prior to their being placed together in a pile, or (b) had prior experience with the objects making up the collection. Our findings suggest that infants' expectations about object behavior are highly specific regarding the entities they are applied to. They do not automatically apply to any and all portions of matter within the visual field. Both the behavior of an entity, and infants' prior experience play roles in determining whether infants will treat that entity as an object.     

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.     

Gaze aversion during social interaction in preterm infants: a function of attention skills?

Preterm infants avert their gaze more often and for longer periods in early social interactions compared to full term infants. In previous studies this finding is interpreted as being a function of the higher degree of parental stimulation that is often found in parents of preterm children. The current study explores an additional hypothesis. Since the development of general visual attention abilities is found to be less optimal in preterm children, it is possible that less optimal maturation of attention abilities partially explains the elevated gaze aversion in a social context. Therefore, the current study investigated the association between gaze aversion in a social context and the ability to disengage and shift visual attention in a non-social context in 20 preterm and 42 full term infants aged 4 and 6 months. Results confirm that preterm infants are slower to shift their attention in a non-social context and that they avert their gaze more often in a social context compared to full term children. Furthermore, more frequent gaze aversion during social interaction at 6 months was related to longer disengagement and the shifting of attention at 4 and 6 months, but only within the preterm group. The results suggest that attention maturation is less optimal in preterm children; this can be observed in a non-social as well as a social context. Less attention maturation in preterm children can negatively influence the amount of time they can stay actively involved in social interaction.     

How infants relate looker and object: evidence for a perceptual learning account of gaze following in infancy

In two experiments, it was investigated how preverbal infants perceive the relationship between a person and an object she is looking at. More specifically, it was examined whether infants interpret an adult's object-directed gaze as a marker of an intention to act or whether they relate the person and the object via a mechanism of associative learning. Fourteen-month-old infants observed an adult gazing repeatedly at one of two objects. When the adult reached out to grasp this object in the test trials, infants showed no systematic visual anticipations to it (i.e. first visual anticipatory gaze shifts) but only displayed longer looking times for this object than for another before her hand reached the object. However, they showed visual anticipatory gaze shifts to the correct action target when only the grasping action was presented. The second experiment shows that infants also look longer at the object a person has been gazing at when the person is still present, but is not performing any action during the test trials. Looking preferences for the objects were reversed, however, when the person was absent during the test trials. This study provides evidence for the claim that infants around 1 year of age do not employ other people's object-directed gaze to anticipate future actions, but to establish person-object associations. The implications of this finding for theoretical conceptions of infants' social-cognitive development are discussed.     

Dynamic pointing triggers shifts of visual attention in young infants

Pointing, like eye gaze, is a deictic gesture that can be used to orient the attention of another person towards an object or an event. Previous research suggests that infants first begin to follow a pointing gesture between 10 and 13 months of age. We investigated whether sensitivity to pointing could be seen at younger ages employing a technique recently used to show early sensitivity to perceived eye gaze. Three experiments were conducted with 4.5- and 6.5-month-old infants. Our first goal was to examine whether these infants could show a systematic response to pointing by shifting their visual attention in the direction of a pointing gesture when we eliminated the difficulty of disengaging fixation from a pointing hand. The results from Experiments 1 and 2 suggest that a dynamic, but not a static, pointing gesture triggers shifts of visual attention in infants as young as 4.5 months of age. Our second goal was to clarify whether this response was based on sensitivity to the directional posture of the pointing hand, the motion of the pointing hand, or both. The results from Experiment 3 suggest that the direction of motion is necessary but not sufficient to orient infants' attention toward a distal target. Infants shifted their attention in the direction of the pointing finger, but only when the hand was moving in the same direction. These results suggest that infants are prepared to orient to the distal referent of a pointing gesture which likely contributes to their learning the communicative function of pointing.     

Infants' search for visible objects: implications for the interpretation of early search errors

This study examined the error patterns of 9-month-old infants searching for hidden objects and objects that were visible within a container. Although errors occurred in both conditions, there were important differences between them. When the object was hidden, infants showed significant perseveration in that they searched more often at the object's previous hiding place than at a control location. When the object was visible, however, they made fewer errors and the errors they did make were as likely to be to the control location as to the previous hiding place. These results suggest that infants' errors in searching for a visible object reflect lapses of attention rather than systematic misunderstandings of objects or space and so are not incompatible with an information-processing account of early search.