Developments in young infants' reasoning about occluded objects

Abstract

Eight experiments were conducted to examine 3- and 3.5-month-old infants' responses to occlusion events. The results revealed two developments, one in infants' knowledge of when objects should and should not be occluded and the other in infants' ability to posit additional objects to make sense of events that would otherwise violate their occlusion knowledge. The first development is that, beginning at about 3 months of age, infants expect an object to become temporarily visible when passing behind an occluder with an opening extending from its lower edge. The second development is that, beginning at about 3.5 months of age, infants generate a two-object explanation when shown a violation in which an object fails to become visible when passing behind an occluder with an opening in its lower edge. Unless given information contradicting such an explanation, infants infer that two identical objects are involved in the event, one traveling to the left and one to the right of the opening. These and related findings provide the basis for a model of young infants' responses to occlusion events; alternative models are also discussed.

Fig. 1

Schematic drawing of the habituation and test events in Aguiar and Baillargeon (1999).

Fig. 2

Schematic drawing of the habituation and test events in Aguiar and Baillargeon (1999) and in Experiment 1.

Fig. 3

Schematic drawing of the habituation and test events in Baillargeon and DeVos (1991).

Fig. 4

Mean looking times of the 3- and 3.5-month-olds in Experiments 1 and 1A at the low-and high-window test events.

Fig. 5

Difference in the mean looking times of the 3- and 3.5-month-olds in Experiments 1 and 1A at the low- and high-window test events. Each dot represents an individual infant.

Fig. 6

Schematic drawing of the habituation and test events in Experiment 2.

Fig. 7

Mean looking times of the 3.5-month-olds in Experiments 2, 3, and 4 at the low- and high-window test events.

Fig. 8

Difference in the mean looking times of the 3.5-month-olds in Experiments 2, 3, and 4 at the low- and high-window test events. Each dot represents an individual infant.

Fig. 9

Schematic drawing of the habituation and test events in Experiment 3.

Fig. 10

Schematic drawing of the habituation and test events in Experiment 4.

Fig. 11

Mean looking times of the 3.5-month-olds in Experiments 1, 1A, and 3 (no-preference condition) and in Experiments 2 and 4 (preference condition) in the first pair of test trials (top) and in their initial response during the first test trial (bottom).

Fig. 12

Schematic drawing of the habituation and test events in Experiment 5.

Fig. 13

Mean looking times of the 3-month-olds in Experiment 5 at the large high- and high-window test events. For comparison purposes, this figure also shows the mean looking times of the 3-month-olds in Experiment 1 at the low- and high-window test events.

Fig. 14

Difference in the mean looking times of the 3-month-olds in Experiment 5 at the large high- and high-window test events. Each dot represents an individual infant.

Fig. 15

Schematic drawing of the habituation and test events in Experiment 6.

Fig. 16

Mean looking times of the 3-month-olds in Experiments 6 and 7 at the low- and high-window test events.

Fig. 17

Difference in the mean looking times of the 3-month-olds in Experiments 6 and 7 at the low- and high-window test events. Each dot represents an individual infant.

Fig. 18

Number of infants in Experiments 1, 1A, 3, and 7 who preferred the low- or the high-window test event in each 10-day age span from 91 to 130 days.