Developments in infants' search for displaced objects.

In an exploratory study of infants' search for displaced objects, 13-month-olds and 21-month-olds were tested on three kinds of displacement problems--visible displacements, invisible displacements, and transpositions--as well as single-hiding problems. Two aspects of performance on the displacement problems were distinguished: (1) searching within the locations involved in the displacement rather than at a control location, and (2) selecting between the displacement locations. Both the younger and the older infants were able to select the correct location on visible displacement problems and to search within the displacement locations on invisible problems. Neither age group was able to solve the transposition problems, but the older infants did at least search within the relevant locations on those problems. Age differences appeared to be due primarily to improved skill at identifying relevant locations rather than to improvements in selecting among those locations. Other factors contributing to the age differences in performance were a decrease in response biases and an increase in skills for coping with multiple possibilities.