Object representation and predictive action in infancy

Previous research has shown that 6‐month‐old infants extrapolate object motion on linear paths when they act predictively on fully visible moving objects but not when they observe partly occluded moving objects. The present research probed whether differences in the tasks presented to infants or in the visibility of the objects account for these findings, by investigating infants’ predictive head tracking of a visible object that moves behind a small occluder. Six‐month‐old infants were presented with an object that moved repeatedly on linear or nonlinear paths, with an occluder covering the place where all the paths intersected. The first time infants viewed an object’s motion, their head movements did not anticipate either linear or nonlinear motion, but they quickly learned to anticipate linear motion on successive trials. Infants also learned to anticipate nonlinear motion, but this learning was slower and less consistent. Learning in all cases concerned the trajectory of the object, not the specific locations at which the object appeared. These findings suggest that infants form object representations that are weakly biased toward inertial motion and that are influenced by learning. The findings accord with the thesis that a single system of representation underlies both predictive action and perception of object motion, and that occlusion reduces the precision of object representations.     

Is the attentional blink effect located in short-term memory?

The attentional blink (AB) effect is characterized by a failure to detect a second target following the identification of a previous target in a RSVP stream. This effect has been attributed to capacity limitations at a central level of visual information processes. Postperceptual models suppose that the AB locus is located in short-term memory. To test this hypothesis, we investigated the influence of a short-term memory deficit on the AB effect in a patient with such a deficit. The three main results of this study are (1) the persistence of an AB effect, (2) a large number of T1 missed identifications and (3) a T2 detection deficit for a specific delay (367 ms). These results indicate that a short-term memory deficit disrupts the processing of each target (T1 and T2) but does not product an abolition of the AB effect.     

Structuring of Early Reaching Movements: A Longitudinal Study

Reaches, performed by 5 infants, recorded at 19 weeks of age and every third week thereafter until 31 weeks of age, were studied quantitatively. Earlier findings about action units were confirmed. At all ages studied, movements were structured into phases of acceleration and deceleration. Reaching trajectories were found to be relatively straight within these units and to change direction between them. It was also found that at all ages, there was generally one dominating transport unit in each reach. The structuring of reaching movements changed in four important ways during the period studied. First, the sequential structuring became more systematic with age, with the dominating transport unit beginning the movement. Second, the duration of the transport unit became longer and covered a larger proportion of the approach. Third, the number of action units decreased with age, approaching the two-phase structure of adult reaching. Finally, reaching trajectories became straighter with age.     

Development of social perception: a conversation study of 6-, 12- and 36-month-old children

A conversation is made up of visual and auditory signals in a complex flow of events. What is the relative importance of these components for young children's ability to maintain attention on a conversation? In the present set of experiments the visual and auditory signals were disentangled in four filmed events. The visual events were either accompanied by the speech sounds of the conversation or by matched motor sounds and the auditory events by either the natural visual turn taking of the conversation or a matched turn taking of toy trucks. A cornea-reflection technique was used to record the gaze-pattern of subjects while they were looking at the films. Three age groups of typically developing children were studied; 6-month-olds, 1-year-olds and 3-year-olds. The results show that the children are more attracted by the social component of the conversation independent of the kind of sound used. Older children find spoken language more interesting than motor sound. Children look longer at the speaking agent when humans maintain the conversation. The study revealed that children are more attracted to the mouth than to the eyes area. The ability to make more predictive gaze shifts develops gradually over age.     

Face scanning distinguishes social from communication impairments in autism

How closely related are the social and communicative impairments in Autism Spectrum Disorder (ASD)? Recent findings in typically developing children suggest that both types of impairment are highly heritable but have only moderate behavioural and genetic overlap. So far, their respective roles in social perception are poorly understood. Here we show that when looking at other people’s faces, children with ASD who are better at socio‐emotional behaviours than non‐verbal communication look more at the eyes, while those with the opposite profile look more at the mouth (Study 1). For the mouth area, a similar pattern was observed for inverted faces, suggesting that information from this area is perceived on a featural basis. In Study 2, we found that when shown a person performing manual actions, ‘eye‐lookers’ from Study 1 tended to look most at the face of the actor, while ‘mouth‐lookers’ from Study 1 tended to look at the action itself (hand/objects). This result was found in both ASD and typical development. In Study 3, the main finding in Study 1 was replicated in a new sample. Taken together, we interpret these results as supporting the view that the neural systems underlying socio‐emotional versus non‐verbal communication skills are separable, a finding that has important theoretical and clinical implications. The results also suggest that a similar differentiation of looking behaviour may operate in normal development.     

儿童精细动作能力的发展及与其学业成绩的关系

研究了不同精细动作能力的发展、之间的内在联系及其与儿童学业成绩的关系。被试为151名4－8岁儿童以及30名本科生。精细动作能力的测查包括线条填画任务、图形临摹任务以及筷子技能测验。结果发现：（1）不同精细动作能力的发展速度从高到低依次为线条填画能力、图形临摹能力和筷子使用技能;（2）筷子使用技能与线条填画、图形临摹能力都显著相关,线条填画能力和年龄对筷子使用技能具有显著预测作用;（3）不同学业成绩儿童在各类精细动作能力上都存在显著差异。本研究说明,较基本的精细动作能力是复杂工具性技能发展的基础,同时在小学低年级阶段,儿童的精细动作能力与其学习活动之间存在密切联系。     

Emotional reactivity and self-regulation in relation to personality disorders

Associations of both reactive and regulative temperamental features with personality disorders (PDs) are investigated in a sample of 162 normal controls and 89 psychiatric inpatients. Reactive and regulative temperamental features were assessed by means of the BIS/BAS Scales and the Attentional Control Scale. Dimensional PD scores were obtained by using the ADP-IV. All PDs were characterized by low levels of effortful control, cluster C PDs by high BIS and cluster B PDs by high BAS. For several PDs, BIS and effortful control interacted: BIS was only related to severe PD pathology if effortful control was low. Clinical implications of these findings are discussed.     

Spatial determinants of depth perception in two-dot motion patterns

The aim of the present study was to identify spatial properties of motion patterns yielding perceived depth. A model was proposed to describe the different motion patterns in terms of the common and the relative motions of the moving parts. Using motion patterns consisting of two dots moving in straight paths, it was found that there were three different types of relative motions yielding unambiguous percepts: (1) lack of relative motions was perceived as motion in a frontoparallel plane; (2) two-dimensional concurrent motions were perceived as translatory motion in depth; (3) nonconcurrent motions were perceived as rotation in depth. Only two-dimensional motion patterns yielded stable depth percepts. The utility of the proposed vector analysis was discussed, and further research suggested.     

Predictive reaching for moving objects by human infants

To what degree do infants use a predictive strategy when reaching for moving objects? This question was studied longitudinally in five infants from 18 to 36 weeks of age. The aiming of 356 reaches were analyzed by a technique that took into consideration the three-dimensional properties of the reaches. Each reach was divided into ballistic steps and the aiming of each step was calculated and compared with an optimal value. It was found that the infants studied had an ability to reach for fast moving objects in a predictive way. Further, the results show that the predictive ability is remarkably good in the lowest age groups which suggests that it is, at least partly, prewired. What develops seems mainly to be the mobility aspects of reaching which makes for more economical and flexible reaching. Older infants reach successfully for the fast moving object also with a nonpredictive chasing strategy.