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Biomedical subjects

S de Schonen

Publications and source records attributed to S de Schonen.

At least 19 recordsLinked to original sources
PubMed2000

When does inter-hemispheric integration of visual events emerge in infancy? A developmental study on 19- to 28-month-old infants.

Simultaneous attention in the two visual fields and interhemispheric integration of visual information was studied in 19-23 and 24-28-month-old infants. The stimuli were schematic faces within which the pair of eyes was made of either two identical (two circles or two triangles) or two different eyes (triangle-circle, circle-triangle). The faces were presented either in one visual hemifield, on the right or left side of a central fixation point (unilateral presentation), or across the two visual hemifields (bilateral presentation), with one eye of the stimulus on each side of the fixation point. The task was an operant conditioning task where the children had to decide whether the shapes of the two eyes were identical or not. The results show that even the younger subjects were able to perform the task when presented in the unilateral presentation condition, whereas only children aged 24 months and older could learn the task when presented in the bilateral condition. It is concluded that simultaneous attention to the two visual fields and inter-hemispheric co-ordination of visual information emerge very late in development at about the age of 24 months.

Age Factors↗
PubMed1999

Configural and local processing of faces in children with Williams syndrome.

Three experiments investigated face processing in children with Williams syndrome (WS). In Experiment 1, the ability to discriminate different aspects of faces was compared between WS subjects and a group of children individually matched for chronological age (CA-matches) and another group matched for mental age (MA-matches). In Experiments 2 and 3, the ability to process the local and configural aspects of geometrical patterns and faces was assessed within the same groups of subjects. The results indicated that the WSs' overall performance on face recognition was below that of the CA-matches, but similar to that of the MA-matches. This study revealed in addition that the CA- and MA-matches showed a bias toward a configural mode of face and geometrical shape processing, whereas children with WS did not show any bias. These findings suggest that face processing undergoes an abnormal developmental course in WS.

Adolescent↗
PubMed1998

Long-term recognition memory for faces assessed by visual paired comparison in 3- and 6-month-old infants.

It has been argued that operant conditioning is the only type of long-term memory present in infants prior to 6 months of age. In this study, memory for faces was investigated in 3- and 6-month-old infants with a visual paired-comparison task. In Experiment 1, infants were habituated to a face presented in different poses; recognition was assessed after a 2-min or a 24-hr retention interval. The 6-month-old infants and the male but not the female 3-month-old infants exhibited novelty preferences. A 2nd experiment showed that 3-month-old female infants were delayed relative to male infants in their face-processing ability rather than in their memory capacity. The results of Experiment 3 demonstrated in 3-month-olds an electrophysiological correlate of delayed recognition memory. These findings are discussed in the context of the neural systems thought to be involved in visual recognition memory (but not in procedural memory), namely the limbic system.

Child Development↗
PubMed1997

Simultaneous attention in the two visual hemifields and interhemispheric integration: a developmental study on 20- to 26-month-old infants.

Simultaneous attention in the two visual fields was studied in 20-, 24- and 26-month-old infants. The stimuli were pairs of simple geometrical elements. The two elements were presented simultaneously either to one visual hemifield (unilateral presentation), on the right or left side of a central fixation point, or across the two visual fields (bilateral presentation), with one component on each side of the fixation point. The task was an operant conditioning task with two conditions. In the Position condition, subjects had to decide whether the two components were horizontally aligned or not. In the Shape condition, they had to decide whether the shapes of the two components were identical or not. The results show that even the youngest group of subjects was able to reach the learning criterion in the unilateral presentation condition, whereas reaching the learning criterion in the bilateral condition becomes possible only at the age of about 24 months. No differences in the subjects' performances were found to exist between the Position and Shape conditions. It is concluded that simultaneous attention to the two visual fields and the production of a unified response emerge very late in development at about the age of 24 months.

Attention↗
PubMed1995

Postural effects of motion vision in young autistic children.

We present the first assessment of motion vision in childhood autism. Postural reactivity to visually perceived motion was measured in five autistic children and 12 normal controls of the same chronological age. Anteroposterior as well as total body sway occurring on a force platform in response to movements in the visual environment were compared. Autistic children were posturally more unstable than normal children and quite insensitive to visually perceived environmental motion. Some implications of this impairment for sensorimotor and social communication development in infantile autism are discussed.

Autistic Disorder↗
PubMed1994

Recognition memory in 3- to 4-day-old human neonates.

It has been recently established in both adult monkeys and humans that visual recognition memory, as assessed with a preferential visual fixation technique, depends on the integrity of the neural structures situated in the medial part of the temporal lobe. This kind of memory has been observed in infant monkeys not earlier than day 15. Using a familiarization technique we established that this recognition memory is present in human infants as early as postnatal day 3 when a 2-min retention interval is used. This visual recognition memory might be controlled by subcortical structures. The possibility that the medial temporal structure involved in adult visual memory is operating at birth cannot, however, be ruled out.

Cognition↗
PubMed1994

Face recognition in children with early right or left brain damage.

Development of face processing after unilateral brain lesions sustained before one year of age was assessed in children aged between seven and 10 years by various tasks involving face processing. Each child was paired with an age- and IQ-matched control. There were three unilateral right-hemisphere lesions and three unilateral left lesions. The results showed that some of the skills relative to face processing were preserved (or recovered?), whereas other skills were severely impaired; the pattern varied from one child to another. The existence of these dissociations shows that preservation of low-level visual processing together with exposure to the appropriate stimuli for several years is by no means sufficient for face processing skills to develop normally.

Brain Damage, Chronic↗
PubMed1991

Visual field asymmetries for pattern processing are present in infancy. A comment on T. Hatta's study on children's performances.

From a study on 4 to 6 year-old children, Hatta (Hatta, Neuropyschologia 28, 1053-1062, 1990) concludes that (a) a left visual-field advantage develops at age 4 to 5 years in visuo-spatial stimulus recognition, and (b) since both the right visual-field advantage for verbal and the left visual-field advantage for visuo-spatial material develop at the same age, there is no support for the claim that the left and right hemispheres develop differentially. We contest these conclusions on the basis of our own infant studies which have shown a right visual-field advantage in 4 to 9 month-old infants for individual face recognition and more recently, for some aspects of visual patterns.

Child, Preschool↗
PubMed1991

Hemispheric asymmetries in visual pattern processing in infancy.

A right hemisphere advantage was observed in a previous study of 4- to 9-month old infants presented with a face discrimination task (de Schonen & Mathivet, 1990). The present study was designed to investigate pattern processing by the two hemispheres and the interhemispheric communication of this processing. Infants aged 4 to 9 months were tested with divided visual field presentations in one or two discrimination tasks. Under both task conditions, the infants had to discriminate between two patterns in which only two local components differed. Under one condition the components of the patterns were arranged so as to produce a face-like pattern. Under the other condition the same components were arranged into arbitrary patterns that were not "good form" patterns. No performance asymmetry was observed with the arbitrary patterns; whereas, a right hemisphere (RH) disadvantage was observed with the face-like patterns compared with both the RH performances on the arbitary patterns and the left hemisphere (LH) performances on the face-like patterns. These results show that the RH advantage for individual face recognition is not due to a general immaturity or inability of the LH in pattern processing at this period of development, nor to a more specific inability in a local mode of pattern processing. On the other hand, the RH does not completely lack local processing capacity, but is at a disadvantage when this local mode of processing has to be used with face-like (or good form) patterns. The interhemispheric communication of visual discrimination learning was tested by measuring learning transfer between the visual fields. Contrary to de Schonen and Bry's study (1987) on faceness recognition, no data in favor of interhemispheric communication were recorded in the present study.

Attention↗
PubMed1990

Hemispheric asymmetry in a face discrimination task in infants.

A right-hemisphere advantage in a mother's face recognition task in infants aged between 4 and 10 months was found to exist by de Schonen, Gil de Diaz, and Mathivet. The present study was designed to test (a) whether the right-hemisphere advantage would still prevail if the task requirements were different from those in the previous study, and (b) whether any information was communicated from one hemisphere to the other. 18-42-week-old infants were presented with an operant conditioning situation where they had to discriminate between their mother's and a stranger's face within one visual hemifield. Transfer of learning from one visual hemifield to the other was also measured. The results confirm the existence of a right-hemisphere advantage in discriminating between face stimuli. This advantage was weaker in the female than in the male population. No hemispheric transfer of learning was observed to occur.

Arousal↗
PubMed1987

Interhemispheric communication of visual learning: a developmental study in 3-6-month old infants.

Infants aged 12-26 weeks (3-6 months) were presented with a visual category discrimination learning task (normal vs scrambled faces) in the right or left visual field. Once they had reached the learning criterion, they were tested for transfer to the untrained visual field in order to establish whether visual experience can be communicated to the opposite hemisphere. Transfer of learning was found to occur in infants aged 19-26 weeks but not in younger ones. Neural pathways possibly forming the channels for this communication are discussed.

Aging↗
PubMed1986

Self-recognition: a study of a population without mirrors.

The study of the influence of familiarity with mirrors on children's capacity to identify their reflected images permitted differentiation between two problems that confront the child in the mirror situation: (a) the identity of the image and (b) the capacity to relate mirror space to real space. Sixty children, 6 to 26 months old, without previous experience with mirrors, were observed systematically while discovering their mirror image and a reflected object. Their behavior was compared to a control group with habitual mirror familiarity. The results suggest that (a) self-recognition in the mirror is independent of the child's familiarity with reflecting surfaces and (b) the capacity to relate mirror to real space seems to be strongly influenced by previous experience with mirrors.

Affect↗
PubMed1978

Central and peripheral object distances as determinants of the effective visual field in early infancy.

While visually fixating on a central, coloured object, thirty-six infants aged between two and five months were presented with a peripheral target to the right or to the left of midline. Both objects were presented at two distances: either 30 or 90 cm from the infant. The extent of the effective visual field was measured by the presence and the latency of saccadic shifts of gaze from the fixation object toward the target object placed at varying degrees of eccentricity. The effective visual field expanded between two and four months. Near peripheral targets were detected at greater angles of eccentricity than those more distant, but this effect was modified both by age and by the distance of central fixation. For two- and three-month infants the effective visual field was most reduced when the central fixation object was placed at 30 cm and the target object at 90 cm. The ability to respond to peripheral objects more distant than the fixation object develops after three months.

Age Factors↗