This study was designed to determine if the failure of previous investigations to find habituation and response to novelty in infants younger than 2 months of age was because the stimuli used were too complex or because a constant number of trials rather than an individual criterion of habituation was used. A total of 24 infants between 5 and 6 weeks of age were divided into three groups and given pretest to show that they had no initial preference for either of two stimuli, which differed in complexity. Next, all infants were given some familiarization with one of the stimuli, followed by a posttest on both stimuli. During the familiarization period, the three groups were treated differently: each of two groups was familiarized with either the complex or simple stimulus, and the third group was familiarized with the complex stimulus, but allowed only half as many familiarization trials. Results indicate that: (1) 5-week-old infants do habituate to visual stimuli, (2) previous failures to demonstrate habituation were due to stimulus and procedural limitations, and (3) preference for novelty is found following attainment of individual habituation criterion, while preference for familiarity is found following a period of familiarization too short to permit attainment of such a criterion. (BRT)