Infants' visual perception of number change was investigated in three studies. These studies focused on infants' perception of events in which the total number of objects in a small group was changed through addition of another object. Involving 60 infants 5 months of age, Study I attempted to determine whether subjects perceived the properties in…

Infants were tested at 5, 8, and 13 months of age for numerosity perception. Subjects observed displayed figures on a screen moving at constant speed with irregular trajectories and occasional occlusions. Results demonstrated that discrimination of units, and not of characteristic patterns, underlies numerosity perception. (BC)