Temporal modulation enhances the efficiency of spatial offset discriminations by 6-month-olds

Fourteen- and 24-week-old infants were tested for sensitivity to small position differences under two conditions: (a) the Vernier stimulus was flashed on and off at 1.2 or 4.8 Hz (flash condition); and (b) the Vernier breaks were presented in apparent motion at 1.2 or 4.8 Hz (motion condition). The latter stimulus also contained local flicker cues. Each infant was tested at one temporal frequency with both stimuli. No benefit was shown by 14-week-olds at either temporal frequency from the additional motion and flicker cues. However, 24-week-olds required spatial offsets only one third as large in the motion condition as they required in the flash condition at 4.8 Hz. Ideal observer methodology was used to ensure that the spatial information for both of these discriminations was held strictly equivalent. Increasing sensitivity to flicker and/or motion or uncertainty reduction may underlie the enhancement in discrimination shown by 24-week-olds at 4.8 Hz.