Number-based expectations and sequential enumeration by 5-month-old infants.

Two studies used the visual expectation paradigm to determine whether 5-month-old infants spontaneously use the number of pictures appearing in one location (left) to predict when a stimulus will appear in a second location ( right ). Infants' eye movements were recorded by using infrared corneal reflection photography while they viewed either a numerically predictable or a numerically unpredictable repeating sequence of pictures. Neither stimulus timing parameters nor stimulus identity predicted future stimulus location. Analyses of anticipatory saccades provided strong evidence that infants rapidly recognize and use the number of sequentially presented pictures ( 2 in Experiment 1, 3 in Experiment 2 ) to predict the location of the next picture in the sequence. Results are discussed in relation to process models ofcounting and subitizing and emphasize the need for these models to accommodate early sequential enumerative capacities.