Twelve-week-old infants were given a battery of perceptual cognitive tasks. These tasks included the Corman-Escalona Scales of Object Permanence, the Mental Development Index of the Bayley Scales, and an attention task measuring habituation and dishabituation. The data failed to show any sex or social class differences, although the MDI was affected by birth order with first borns showing superior performance. In general these three measures of perceptualcog ability were unrelated. These data are used to question the notion of a "g" factor in infancy and therefore the usefulness of a test of infant intelligence. (29pp.)