||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.