Facilitated discrimination learning as effected by response-contingent neutral and aversive stimuli

Abstract

To assess the cue interpretation of the shock-right (SR) facilitation phenomenon, rats received visual discrimination training in which, for different groups, neutral and aversive intensities of white noise were presented selectively contingent on either right or wrong responses or nonselectively contingent on both responses. The nonselective (yoked) contingency groups did not differ from a no-noise control group at any of the noise intensities tested. In contrast, the selective contingency (noise-right and noise-wrong) groups showed comparably facilitated performance which was a positive S-shaped function of noise intensity. These findings cast doubt on an “alerting” or “sensitizing” function of the stimulus and indicate instead that, when selectively applied to a response, the stimulus effectively operates as a distinctive cue to increase the discriminability of the alternatives and thereby facilitate performance. That such facilitation obtains with a neutral as well as an aversive stimulus and relates, in accord with the Weber function, to the intensity characteristics of the stimulus argues strongly that the SR phenomenon is appropriately viewed as a stimulus-right effect.