RESPONSE MODALITY AFFECTS HUMAN INFANT DELAYED-RESPONSE PERFORMANCE

Delayed response performance was assessed in 120 7-, 9-, and 11-month- old infants with correct response defined as either retrieval of a hid den object or gaze toward the location where the object was hidden. Pe rformance improved with age, was above chance for each age group in ea ch condition, and was more often correct with the gaze response. When direction of gaze and reach differed, direction of gaze was more likel y to be correct. Infants in the reach condition were more likely to fa il to reverse a previously correct response (i.e., to make the A-not-B error). Perseverative responding occurred frequently and was more lik ely in the reach than the gaze condition. This effect emerged primaril y in the context of an incorrect response, which suggests modality-spe cific sensitivity to the effect of priming rather than reinforcement. Many infants showed strong side biases, and there was a tendency for m ore reaches to the left but gazes to the right. In a second experiment , 12 5-month-olds gazed toward the correct location more frequently th an would be expected by chance but failed to reverse a previously corr ect response more often than older infants. These findings indicate th at response modality has a significant effect on delayed-response perf ormance.