Lever-Pressing Responses of Wild Cotton and Wistar Rats

Abstract

Barnett ( 1 ) and Kavanau ( 2 ) indicate that the behaviors of wild and tame rats differ in many respects. This note presents lever-pressing data for 2 120-day-old male Wistar rats and 1 male and 1 female wild Cotton rat (Sigmodon hispioris texianis). The latter 2 were caught in the fields of South-central Kansas (estimated age 60 days), and kept in the lab until testing at approximately 150 days. A Stoelting Skinner Box No. 31292 delivered one drop of water each time S pressed the lever. Lever pressing was always signalled by the flash of an overhead lamp and an audible click. All Ss prior to testing were on an ad lib, regimen of lab-chow and water. Food was available at all times when Ss were in the apparatus. All Ss were naive with respect to the conditioning apparatus. The testing schedule was as follows: ( a ) one male albino rat was placed in the apparatus for 72 hr, with water reinforcement for each lever press and this session was followed immediately by 72 hr. without water reinforcement for lever presses, ( b ) 1 male Cotton rat was placed in the apparatus until his total lever presses approximated those of the albino rat and this session was immediately followed by an equal period without water reinforcement (see Fig. 1 for time and total lever presses), ( c ) 1 male albino and 1 female Cotton rat were individually tested in the apparatus for periods corresponding to their partner's first test period, but they were never reinforced for lever pressing.