Spontaneous alternation is a reduced tendency to return to the same location on successive trials. It is measured in rats in a T maze and is thought to depend on an intact hippocampus. In human infants, we measured alternation in the tendency to reach toward one of two identical toys placed in locations to the left and right of midline. Infants at 6 months returned to the same side as frequently as they alternated, but 18--month-old infants showed a significant alternation pattern. At 6 months, infants show inhibition of return, but do not show alternation in motor behavior; at 18 months, infants show both, but they are negatively related. These data suggest that preference for novelty may rest on different internal mechanisms even in quite similar tasks, and suggest that whereas inhibition of return is related to control by the posterior attention network, spontaneous alternation may be related to inhibitory control by the anterior attention network.

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