Frequency-difference thresholds in Chinchilla using conditioned avoidance techniques

Abstract

Chinchillas were trained to discriminate or detect pure-tone frequency differences using shock-avoidance procedures. Two psycho-physical paradigms were investigated. Initial attempts at determining frequency-difference thresholds utilized a complex discrimination paradigm. Although discriminations of large frequency differences were obtained from Chinchilla with adequate success, discriminations of very small frequency differences could not be trained. Therefore, determinations of frequency-difference thresholds were not possible with this complex discrimination paradigm. A second relatively simple detection paradigm, involving the detection of frequency alternation in an on-going train of tone bursts, proved to be a somewhat more successful technique. Frequency alternation detection was quickly learned by the Chinchillas and frequency-difference thresholds were obtained with an adaptive sequential procedure. Those frequency-difference thresholds are comparable to frequency-difference thresholds obtained in other animal species by previous investigators. Some of the difficulties in maintaining reliable behavior in Chinchillas with shock avoidance techniques are discussed. [Work supported by DRF grant.]