Infants' delayed recognition memory and forgetting

Infants 21- to 25-weeks-old devoted more visual fixation to novel than to previously exposed stimuli on immediate and delayed tests of recognition. Abstract black and white patterns were recognized following a 48-hour delay and photos of faces after a 2-week delay. A decline in recognition over 3 hours for targets (face masks) most akin to objects (real faces) in S's environment led to studies of the effect on delayed recognition of exposure to stimuli similar to those to be retained. One-minute delayed recognition for face photos was disrupted by intervening exposure to intermediate similarity stimuli (rotated photos) but was unaffected by exposure to either high (upright photos) or low (rotated line drawings) similarity stimuli. Differentiation among intervening stimuli occurred only for the upright photos used as high-similarity intervening material. In addition, immediate exposure to rotated photos also prevented 3-hour-delayed recognition of upright photos but had no such effect when delayed for 3 hours. The present experiments confirm the existence of long-term recognition memory for pictorial stimuli in the early months of life and show that one source of forgetting is due to a diversion of the infant's attention to material bearing some perceptual similarity to the material to be retained. This diversion of attention must occur soon after immediate recognition testing to produce a reduction of recognition and such deleterious effects last for an appreciable period of time.