Open-Field Activity of Albino Rats as a Function of Sex, Age, and Repeated Testing

Forced open-field exploration of Wistar rats was examined as influenced by age, sex, and repeated testing. The first phase of the study compared nine days of repeated testing among 28- and 98-day-old males and females. The older groups decreased in activity during the initial testing days. The younger groups increased above the older rats' activity levels during the last days of testing. Females generally had higher activity than males. The younger rats were tested at 48, 68, 88, and 108 days of age in the second phase of the study. Females had higher activity than did males and no interactions of sex with age or repeated testing days were significant. When subjects were 48 and 68 days old activity increased more rapidly over the six testing days compared to the 88- and 108-day-old periods. Results are discussed in relation to previous research using forced- and free-exploration procedures.