Measurement and quantification of stereotypy in freely behaving subjects: An information analysis

Stereotypy is typically defined as abnormal, repetitive, and purposeless motor behavior. In this study, stereotypy was more rigorously and generally defined in terms ofH, the typical metric for entropy, and was measured using computer-driven analyses of filtered and digitized video records. This technique was validated using rats treated with d-amphetamine, which has been shown to be an effective stimulant of traditionally defined stereotypy in a wide variety of species. Rats were treated with 0, 1, 2, and 4 mg/kg body weight d-amphetamine sulfate, and their unrestrained behavior was recorded on videotape. Our results confirm previous research that found stereotypy to occur at high doses of amphetamine. However, the present measure of stereotypy brought out additional complexities. Our results indicate that stereotypy occurred at significant levels with low drug doses, and, furthermore, that stereotypy in general was highly dependent upon the level of behavioral complexity considered. Finally, we discuss the advantages of the present metric for studying stereotypy.