DISENGAGING VISUAL-ATTENTION IN THE INFANT AND ADULT

The latency to make an eye movement towards a phase-reversing peripheral target was measured in 1.5-, 3-, and 6-month-old infants and adults using four interleaved conditions. In the short-gap condition, the central fixating stimulus (schematic face) disappeared 240 ms prior to the onset of the peripheral target. In the long-gap condition, the interval between the offset of the central stimulus and the target was 720 ms. In the no-overlap condition, the appearance of the peripheral target coincided with the offset of the central stimulus, and in the overlap condition, the central stimulus remained present for 2,120 ms following the onset of the peripheral target. In general, latencies decreased with age, though there was very little difference between the 3- and 6-month-olds. Gap conditions produced the fastest saccadic latencies compared to the no-overlap and overlap conditions in all groups. In line with previous studies, the overlap condition produced the slowest responses, even for adults who had been instructed to make an eye movement as quickly as possible. However, a manual response measure in the adult group using the same paradigm did not produce longer latencies for the overlap condition, suggesting that the effect may be specific to mechanisms controlling saccades and not motor responses per se. The short latencies for gop conditions and the longer saccadic latencies in the overlap condition are taken as evidence to support a cortical disengagement hypothesis of orienting eye movements.