Does surprise enhance infant memory? Assessing the impact of the encoding context on subsequent object recognition

A discrepancy between what was predicted and what is observed has been linked to increased looking times, changes in brain electrical activity, and increased pupil dilation in infants. These processes associated with heightened attention and readiness to learn might enhance the encoding and memory consolidation of the surprising object, as suggested by both the infant and the adult literature. We therefore investigated whether the presence of surprise during the encoding context enhances subsequent encoding and recognition memory processes for the items that violated infants’ expectations. Seventeen-month-olds viewed 20 familiar objects, half of which were labelled correctly, while the other half were mislabelled. Subsequently, infants were presented with a silent recognition memory test where the previously labelled objects appeared along with new images. Pupil dilation was measured, with more dilated pupils indicating (1) surprise during those labelling events where the item was mislabelled and (2) successful retrieval processes during the memory test. Infants responded with more pupil dilation to mislabelling compared to correct labelling. Importantly, despite the presence of a surprise response during mislabelling, infants only differentiated between the previously seen and unseen items at the memory test, offering no evidence that surprise had facilitated the encoding of the mislabelled items.