Effect of Practice and Feedback on Frequency Discrimination

Differential thresholds for frequency were obtained from 20 normal hearing, but otherwise unselected, subjects using the method of constant stimulus differences for 6 hours. For each subject twelve difference limens (DL's) and constant errors (CE's) were calculated. The subjects were divided into two groups of ten each: group 1 received feedback, or immediate knowledge of results, in hours 1, 2, 4, and 6; group 2 received feedback in hours 2, 4, and 6. Group 1 had considerably larger DL's and CE's throughout the six hours than did group 2. Both groups showed smaller DL's the last hour (median = 4.2 cps) than on the first (7.3 cps), with no indication that learning was complete. CE's became less variable with practice, but the median CE (−1.0 cps the first hour and −0.8 cps the sixth) showed essentially no change. The effects of feedback in the last four hours were slight and largely obscured by variability and the general improvement with practice.