The visual-preference technique in infancy: effect of number of stimuli presented upon experimental outcome.

To examine the effects of the number of stimuli presented when the visual-preference technique is used to measure attention in infancy, 2- and 4-month-old infants were randomly assigned to 1 of 3 experimental conditions. In the first condition, infants were shown 3 different checkerboards using the single-stimulus visual-preference methodology; in the second condition, 4 checkerboards; and in the third condition, 5 checkerboards. Infants in both the 3- and 4-pattern conditions were able to order the patterns as predicted by scaling theory. However, there was a significant decrease in the number of infants in the 5-pattern condition who could do so. The results are discussed in terms of both their methodological and theoretical implications.