Décalage in infants' knowledge about occlusion and containment events: converging evidence from action tasks

Abstract

In the present research, 6-month-old infants consistently searched for a tall toy behind a tall as opposed to a short occluder. However, when the same toy was hidden inside a tall or a short container, only older, 7.5-month-old infants searched for the tall toy inside the tall container. These and control results (1) confirm previous violation-of-expectation (VOE) findings of a décalage in infants' reasoning about height information in occlusion and containment events; (2) cast doubt on the suggestion that VOE tasks overestimate infants' cognitive abilities; and (3) support recent proposals that infants use their physical knowledge to guide their actions when task demands do not overwhelm their limited processing resources.

Fig. 1

Stimuli used in the present research. Top: The tall, stuffed, toy frog had a green and yellow body, black and white eyes, a pink and red mouth, and a black top hat. A stiff wire in the frog's back enabled it to remain upright when seated. In this position, the frog was 21 cm tall and 9 cm wide and its legs were 23.5 cm long and 5 cm wide (at their largest points). At the start of each trial, the frog was placed on a table 115.5 cm wide and 125.5 cm deep, centered against a screen 30 cm high and 58 cm wide; the table and screen were covered with blue contact paper. Bottom: The tall and short containers used in the containment condition were made of PVC pipe 10 cm in diameter and had bottoms made of cardboard; they were covered with textured white contact paper and their top rims were painted black. The tall container was 23 cm tall and its interior was painted red; the short container was 8.5 cm tall and its interior was painted blue. Frog legs identical to those of the tall frog protruded from two small holes at the bottom of each container; these legs were attached to frogs that were cut at the waist (and not visible to the infant). The containers rested on a platform 0.5 cm high, 60 cm wide, 24 cm deep, and covered with white marbled contact paper. The containers were placed 7.5 cm on either side of the platform's midline, centered front to back. The tall and short occluders used in the occlusion condition were identical to the front halves of the tall and short containers, and they were placed in the same positions on the platform. Frog legs protruded from around the bottom left and right edges of each occluder; the legs wrapped around the occluder and the feet stuck out in front, as with the containers.

Fig. 2

Top: Percentage of infants in each age group who reached for the tall container or occluder (or its frog legs) on at least three of the four trials. When infants touched the two containers or occluders in succession, only the one touched first was entered in the analyses; this occurred on 5% of the trials. When infants touched the two containers or occluders simultaneously on one trial, that trial was coded as incorrect; this occurred for 2/100 infants, one in the occlusion-control and one in the containment-control condition. Infants who touched the two containers or occluders simultaneously on two or more trials were eliminated and replaced (see Section 3.1.1). Bottom: Percentage of reaches to the tall container or occluder in each age group and condition.