Measuring infant spatial working memory using a modified delayed-response procedure

Infant spatial working memory was assessed in 96 nine-month-old human infan ts using a modification of the delayed-response procedure. A person was the hidden stimulus, gaze was used as the response modality, the response cont ext was a naturalistic "peek-a-boo" game, and a salient cue (i.e. curtains opening to reveal two windows) was used to evoke responses. Infants respond ed on most trials and performed significantly above chance in delay conditi ons of 10 and 20 seconds. Reinforcement affected performance, but performan ce was above chance even in a 0% reinforcement condition. These procedural variations boost estimates of infant spatial working memory over previous e stimates and enhance the usefulness of the delayed-response procedure as a marker task for infant spatial working memory.