Observing behavior in the albino rat: a within-subjects' comparison of increasing levels of visual complexity

54 male CD strain Charles River albino rats were tested for complexity preference using a non-locomotor response. Each subject was presented an array of photographic slides containing an incremental series of complexity elements, i.e., 1, 2, 5 and 25 elements. All photographic slides were randomized both within and across subjects. Each photographic slide of each level of complexity was repeated three times. Results of an analysis of covariance, with luminance as the covariate, showed that cummulative viewing time increased with an increase in stimulus complexity. The relationship between looking and level of complexity was shown to be different when covariance procedures were used than without them.