Auditory Discrimination Learning as a Function of Intensity Differences

Abstract

Four groups of four rats each were trained for 240 hours on an auditory intensity discrimination, the stimuli being correlated with a multiple variable interval-extinction schedule of reinforcement. For each group a 4 kHz (cps) tone of 60 db was the SD (reinforced intensity). A 4 kHz tone of either 70, 80, 90 or 100 db was the SΔ (nonreinforced intensity). The slope of the mean as well as the individual learning curves which describe discrimination acquisition was an increasing function of SD-SΔ difference. This result is contrary to the predictions of certain two-stage or chaining models of discrimination learning. Some suggestions are made as to the possible sources of difference in both stimulus and response variables between the present experiment and those upon which the two-stage models are based.