The advantage of real objects over matched pictures in infants' processing of the familiar size of objects

We investigate when infants exhibit knowledge of the familiar size of well-known objects and whether this knowledge is affected by stimulus format, that is, whether the stimuli are presented as real objects or matched pictures. Infants (130 7- and 12-month-olds) saw everyday objects such as sippy cups and pacifiers in their familiar size and novel sizes (larger or smaller than the familiar size) placed pairwise within infants' reach. We used a preferential-looking paradigm to investigate whether infants are able to discriminate familiar from novel sizes. Although, infants of both age groups looked longer toward real objects that were smaller or larger than the familiar size, there were no looking preferences for the pictures. These results suggest that although 7- and 12-month-olds demonstrate familiar size knowledge for real objects, this understanding does not generalize to pictorial representations of those objects.