Olga Kochukhova

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 childrens 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.

Extrapolation and direct matching mediate anticipation in infancy

Why are infants able to anticipate occlusion events and other peoples actions but not the movement of self-propelled objects? This study investigated infant and adult anticipatory gaze shifts during observation of self-propelled objects and human goal-directed actions. Six-month-old infants anticipated self-propelled balls but not human actions. This demonstrates that different processes mediate the ability to anticipate human actions (direct matching) versus self-propelled objects (extrapolation).

Integrated global motion influences smooth pursuit in infants

Smooth pursuit eye movements (SP) were studied in 5- and 9-month-old infants and adults in response to a rhombus oscillating horizontally behind three spatially separated vertical occluders. During motion, the rhombus vertices were never visible. Thus the perception of the global motion of the rhombus required integration of its moving visible segments. We tested whether infants were able to use such perceived global motion for SP in two different occluder conditions; one in which the occluder was clearly visible to the observer and one in which it was invisible. In adults, the presence of a visible occluder hiding the vertices of the rhombus strongly facilitates the perception of the global motion. It was found that adults and 9-month-olds performed significantly more horizontal SP in the presence of a visible occluder but not 5-month-olds. Furthermore, this tendency was strengthened over single trials, and this temporal pattern was very similar in all age groups. In the invisible occluder condition both adults and infants tracked the segments of the rhombus primarily with vertical SP. It was concluded that the ability to integrate moving object fragments into perceived global motion and use that to regulate SP develops into adult performance by 9 months of age.

Temperament differences between institution- and family-reared toddlers.

The goal of this study was to compare the temperamental properties (i.e. Surgency/extraversion, Negative affectivity, Effortful control) of institution-reared (IR) and family-reared (FR) toddlers, aged between 17 and 37 months, living in Simferopol, Crimea. The results demonstrated significantly lower Surgency and higher Negative affectivity scores in the institution-reared toddlers. At the same time, in IR children Surgency scores depended on childrens age, the older the children were, the higher scores they were assigned. No such relation was found for FR toddlers. Further, level of Negative affectivity in IR group depended significantly on amount of time that children spent at the institution; more time resulted in higher Negative affectivity scores. We could not find any differences between IR and FR children in Effortful control. The study results suggest different developmental patterns for Surgency and Negative affectivity in IR and FR children and are discussed in terms of potential impact it may have on further personality development.

Neurophysiological Analysis of Speech Perception in 2.5 to 3.5-Year-Old Orphans and Children Raised in a Family

In 2.5-3.5-year-old orphans (n = 41) and children raised in a family (n = 50), we examined specificities of speech perception-related changes in the spectral power density (SPD) of the EEG rhythms. Changes in the SPDs of the θ-, α-, β-, and γ-rhythms in 16 EEG leads where estimated at presentation of a meaningful speech fragment record (short poem) and of a reversed record of the same signal (direct and reversed speech, respectively). The Bayley Scales of Infant and Toddler Development III demonstrated the existence of noticeable delays in the development of speech in orphans. Comparison of background EEGs and EEGs in the course of listening for direct speech showed that the α-rhythm is desynchronized, while the θ-, β-, and, especially, γ-oscillations are synchronized upon perception of the above stimulus. In this case, children raised in a family demonstrated significant increases in the γ-rhythm SPD in 13 leads of both hemispheres; in orphans, this was observed only in 8 loci localized mostly in the left hemisphere. In children of both groups, listening for reversed speech induced mostly desynchronization of all EEG rhythms with the greatest drops in the γ SPD mostly in the frontal and left temporal leads. Comparison of SPDs of the EEG components (rhythms) at listening for direct and reversed speech demonstrated that powers of θ-, β-, and γ-oscillations increased at presentation of a direct (comprehended) speech in children of both groups. In children raised in families, greater SPDs of the γ-rhythm were observed in 13 leads (differences were most significant in the frontal parts of the left hemisphere). In institutionalized children, the number of leads with significant increments of the γ-rhythm power was significantly smaller (only 9). It is supposed that smaller increases in the SPD of of γ-range oscillations in orphans are related to deviations in the processing of a semantic component of speech perception. This can result from insufficient development of cerebral neuronal networks responsible for processing of verbal information.