The effect of varying levels of complexity within two types of visual stimuli on observing behavior of albino rats (60 females, 30 males, CD Strain, Charles River) was examined. Measures of frequency and duration of looking, as well as measures of general activity, were recorded. Differences in duration of observing as a function of group membership and type of stimuli were obtained. Activity was affected by the level of complexity. A re-examination of the concept of complexity is suggested. Further delineation of variables affecting observing behavior is also needed.