PERCEPTUAL CONSTRAINTS ON INFANT MEMORY RETRIEVAL

In three experiments with 78 3-month-olds, we asked what determines wh ether or not a stimulus will pop out and cue retrieval from long-term memory. All infants were trained with mobiles displaying either Qs (fe ature-present stimuli) or Os (feature-absent stimuli) and were tested 24 h later. When the diagonal line of the Q bisected its rim, feature- absent stimuli controlled retrieval in tests with homogeneous displays , and stimulus novelty controlled retrieval in tests with pop-out disp lays. A follow-up experiment revealed that the similarity between Q an d O determined whether or not Q popped out: When its tail projected ex ternally from the rim, Q popped out and cued retrieval, but O did not (search asymmetry). When its tail projected internally from the rim, h owever, 3-month-olds failed to discriminate Q from O (the externality effect). These data reveal that target-distracter similarity constrain s whether or not a feature-present stimulus will pop out and cue retri eval. (C) 1998 Academic Press.