Development of Visual Size Constancy During the 1st Year of Human Infancy

Visual size constancy for distances up to 70 cm was studied in three experiments with 4-, 6-, and 8-month-old infants and up to 200 cm with 6-month-old infants in a fourth. A habituation-test procedure was used throughout. At each age subjects were repeatedly shown a three-dimensional model of a human head until a criterion of habituation of looking was reached. Relative to the habituation condition, the standard test condition was either the same (control) or different in distance, size, or both size and distance. Appropriate comparisons between the recovery scores for the test conditions showed that at 6 and 8 months, size constancy occurred for the head model up to a distance of 70 cm. This was not so for 100 cm and 200 cm. At 4 months size constancy measured in the same way as for older subjects was not apparent in the range 30-60 cm, but there was a suggestion that it is present at this age among those infants with lower variance of responding.