Behavioral and Cortical Measures of Infants' Visual Expectations

Abstract

AbstractFeatures of the habituation paradigm were combined with the visual expectation paradigm to examine behavioral and cortical indexes of infants' visual expectations. Eight 3‐month‐old infants watched an alternating picture sequence while their eye movements were videotaped and their cortical electrophysiological activity (event‐related potential [ERP]) was recorded. Two ERP epochs were examined: a 3,000‐msec stimulus‐locked epoch included 1,000 msec before stimulus onset through 1,000 msec after stimulus offset; and a 1,200‐msec response‐locked epoch included 700 msec before saccade onset through 500 msec after the saccade. All infants anticipated upcoming pictures, and eye movement latencies for pictures that were not anticipated were comparable to saccade latencies reported in other visual expectation studies of infants at this age. Three components were identified in the stimulus‐locked ERP waveform: a slowly developing negativity prior to picture onset, a postonset negative slow wave, and a late negative deflection that peaked about 750 msec after picture onset. All stimulus‐locked components were larger for familiar than for unfamiliar pictures; prestimulus negativity was also greater before anticipated pictures. The response‐locked waveform contained 2 prominent features: a slowly increasing negative shift (NS) that began about 500 msec before saccade onset and a positive presaccadic potential that occurred about 30 to 90 msec before the saccade. Response‐locked components were larger for anticipatory saccades at the frontal scalp site; for reactive saccades, response‐locked components were larger at the vertex. Results are informative about ERPs in infants, cortical control of eye movements, and the development of visual expectations.