Development of temporal contrast sensitivity in human infants.

The time course for the development of the temporal contrast sensitivity function in humans is uncertain. Some studies indicate that temporal contrast sensitivity is immature in infants. However, earlier work suggests that critical flicker fusion is adult-like by 2 months. We traced the development of temporal contrast sensitivity to uniform field flicker in 2-, 3- and 4-month-old infants using a modified preferential-looking technique that employed a rating scale. Two-month-old infants exhibited highest sensitivities at 1 and 2 Hz. Three- and 4-month infants exhibited peak sensitivity at 4 and 8 Hz, respectively. Overall temporal contrast sensitivity increased with age and the peak frequency shifted toward higher temporal frequencies. Using this paradigm, no infant subjects showed responses to 32 Hz, the highest temporal frequencies tested.