Factors affecting infants’ manual search for occluded objects and the genesis of object permanence

Abstract

Two experiments systematically examined factors that influence infants' manual search for hidden objects (N = 96). Experiment 1 used a new procedure to assess infants' search for partially versus totally occluded objects. Results showed that 8.75-month-old infants solved partial occlusions by removing the occluder and uncovering the object, but these same infants failed to use this skill on total occlusions. Experiment 2 used sound-producing objects to provide a perceptual clue to the objects' hidden location. Sound clues significantly increased the success rate on total occlusions for 10-month-olds, but not for 8.75-month-olds. An identity development account is offered for why infants succeed on partial occlusions earlier than total occlusions and why sound helps only the older infants. We propose a mechanism for how infants use object identity as a basis for developing a notion of permanence. Implications are drawn for understanding the dissociation between lookingtime and search assessments of object permanence.

Understanding the effects of one's actions upon hidden objects and the development of search behaviour in 7‐month‐old infants

“…In assessing the success of such searching and means‐end retrieval actions, it has been noted that actions should only be considered to be successful if they could be judged to have been performed with the expectation that the action would result in being able to retrieve the toy (e.g. Willatts, ; Moore & Meltzoff, , ). We measured this expectation by considering the gaze direction of the infants as they revealed the toy (or rotated the turntable through 90 degrees for the turntable trials), and whether they then made a reach for it.…”

Sound effects: Multimodal input helps infants find displaced objects

“…Three hypotheses were tested. First, if sound enhances object processing (Moore & Meltzoff, ), the audible groups should outperform the silent groups at B. Second, if the absence of visual input enhances processing during the delay (Miller et al ., ), the dark groups should outperform the light groups.…”

“…When stationary objects are hidden by visible occluders (e.g., covers), infants fail to use sound to find them before 9 months (Bigelow, ). Eight‐month‐olds who saw either an audible or silent object hidden by occlusion retrieved neither object, whereas 10‐month‐olds retrieved silent objects reliably, and audible ones even more (Moore & Meltzoff, ). However, when objects are hidden by darkness, infants under 9 months do use sound (e.g., Clifton, Rochat, Litovsky, & Perris, ).…”

“…Alternatively, perhaps infants represent objects uniformly well from 5 to 12 months, and other immature processes explain uneven performance before 9 months. Insufficient memory might mean infants forget about the object, and sound might remind them of its existence (Moore & Meltzoff, ). Fragile attention might make infants more distractible in the light versus dark (Spelke & von Hofsten, ), making this reminder less effective in the light with occlusion than in darkness.…”

“…(Infants still err with visible objects (Harris, ), so even more salient perceptual input seems insufficient alone.) First, sound might reduce demands on memory for the object's location (Moore & Meltzoff, ). Second, it might focus infants’ attention on the object instead of irrelevant stimuli (e.g., Watanabe, Forssman, Green, Bohlin, & von Hofsten, ).…”