Object individuation and event mapping: developmental changes in infants' use of featural information

The present research examined the development of 4.5- to 7.5-month-old infants’ ability to map different-features occlusion events using a simplified event-mapping task. In this task, infants saw a different-features (i.e. egg-column) event followed by a display containing either one object or two objects. Experiments 1 and 2 assessed infants’ ability to judge whether the eggcolumn event was consistent with a subsequent one-column display. Experiments 3 and 4 examined infants’ ability to judge whether the objects seen in the egg-column event and those seen in a subsequent display were consistent in their featural composition. At 7.5 and 5.5 months, but not at 4.5 months, the infants successfully mapped the egg-column event onto the onecolumn display. However, the 7.5- and 5.5-month-olds differed in whether they mapped the featural properties of those objects. Whereas the 7.5-month-olds responded as if they expected to see two specific objects, an egg and a column, in the final display the 5.5-month-olds responded as if they simply expected to see ‘two objects’. Additional results revealed, however, that when spatiotemporal information specified the presence of two objects, 5.5-month-olds succeeded at tagging the objects as being featurally distinct, although they still failed to attach more specific information about what those differences were. Reasons for why the younger infants had difficulty integrating featural information into their object representations were discussed.