Object identity in preschoolers: constraints in avoiding misidentification.

This study investigated whether preschool children act on the understanding that identical-looking objects can no longer be re-identified once their positions change unnoticed, using an everyday task assessing the ability to avoid misidentification and comparing their performance with that of adults. Although children aged 4 to 7 years (N = 66) reliably and repeatedly identified which of five identical-looking nuggets was a Playmobil figure's "favorite", the majority (56 %) nevertheless failed to separate it when tidying up the five nuggets into two opaque bags. In contrast, all adults (N = 66) did so. The fact that the majority of children failed to separate the verbally marked nugget, despite knowing "which one it was", indicates that they struggle to anticipate that the identity of very similar objects can be maintained only as long as identity-relevant spatial information is available, pointing to a still-developing concept of object identity. Older preschoolers tended to be more successful in separating the figure's favorite nugget than younger ones, suggesting a developmental progression in how spatial identity criteria for objects are conceptualized. In a condition in which the figure's favorite nugget was perceptually distinct (different color), 64 % of another group of children (N = 66) packed it separately, even though this was not necessary, indicating that their behavior was strongly driven by perceptual salience. Taken together, these findings suggest that many preschool children still struggle to use spatial criteria of identity to guide their behavior, even in a context that minimizes memory, attentional, and linguistic demands.