SIMULTANEOUS ATTENTION IN THE 2 VISUAL HEMIFIELDS AND INTERHEMISPHERIC INTEGRATION - A DEVELOPMENTAL-STUDY ON 20-MONTH-OLD 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 geometric al elements. The two elements were presented simultaneously either to one Visual hemifield (unilateral presentation), on the right or left s ide of a central fixation point, or across the two visual fields (bila teral presentation), with one component on each side of the fixation p oint. The task was an operant conditioning task with two conditions. I n the Position condition, subjects had to decide whether the two compo nents were horizontally aligned or not. In the Shape condition, they h ad to decide whether the shapes of the two components were identical o r not. The results show that even the youngest group of subjects was a ble to reach the learning criterion in the unilateral presentation con dition, whereas reaching the learning criterion in the bilateral condi tion becomes possible only at the age of about 24 months. No differenc es in the subjects' performances were found to exist between the Posit ion and Shape conditions. It is concluded that simultaneous attention to the two visual fields and the production of a unified response emer ge very late in development at about the age of 24 months. (C) 1997 El sevier Science Ltd.