Shuttlebox avoidance programs for the 6502

Abstract

Two programs were written in assembly language for the 6502 microprocessor to control a wide variety of learning procedures for a shuttlebox. Both programs can control two shuttleboxes simultaneously. The first program includes routines for the traditional discrete-trial avoidance procedures, including operant level (CS only), avoidance, punishment, and Pavlovian conditioning (US presentation independent of the response). Session parameters (number of trials, durations of the CS, US, and IT!) may be set over a wide range of values, and response-contingent CS termination is an option. Session-identification data, the latency of the first response on each trial, and the total number of intertrial responses are both printed and stored in memory. Latencies, rather than just the occurrence of a response, are measured. Bolles (1979) argued that the failure of the response latencies to change over time is evidence that the animal is showing a species-specific defense reaction rather than avoidance learning. The second program controls the linear presentation procedure described by Zerbolio (1981). This method was developed with the thought that the traditional shuttlebox avoidance procedures do not provide unambiguous evidence for the acquisition of a discriminated avoidance response in goldfish. In the typical avoidance learning experiment, an increase in response rate is taken as evidence for learning. Goldfish present a problem in that they are known to increase their rate of responding not only in the situation in which there is response-contingent shockomission, but also under a large variety of procedures, including no US presentation (Steiner, 1971) and Pavlovian procedures (Woodard & Bitterman, 1971). Zerbolio's procedure provides a parallel to the response requirements of a Y maze. In the shuttlebox, each trial begins with a trial-start stimulus. If the fish responds, by shuttling to the other end of the tank, either an S+ or an Sstimulus is presented on a randomized basis. Ifthe fish makes additional responses on this trial, the S+ and Sstimuli alternate. At the end of the trial, the fish receives the US if the trial-start or S stimuli are in effect. To avoid the