Role of perceptual and conceptual similarity in category matching at age two years.

Perceptual and categorical similarity were varied independently in a concept-matching task administered to 26-month-old children (N = 25). 44 test sets were assembled. Each set included a 3-dimensional standard and an array of 4 pictures, one of which was a member of the same basic or superordinate category as the standard. On each trial, placing the standard on the matching picture resulted in activation of 1 of 12 mechanical displays. The test sets varied in the perceptual and categorical resemblance of the standard to the match and to the nonmatches, as determined by adults' ratings. Perceptual similarity proved to be the primary determinant of difficulty level. When perceptual resemblance of the standard and the match were equated, superordinate and basic matches were equally difficult. When perceptual resemblance was minimal, most children were unable to recognize matches at either the basic or superordinate level.