The present study is concerned with the problem of awareness in the operant conditioning of a nonverbal behavior, eye blinks. Using a within-subjects design, 14 subjects' blink rates were counted and compared for four periods of 4 min each. The experimenter and the subject carried on an informal conversation during both base and reinforcement periods" but during reinforcement periods only, a light flashed on immediately after each of the subject's blinks. The test for awareness consisted of brief questioning after reinforcement periods and a more extensive post experimental interview. Only data for the eight unaware subjects were used in statistical analysis. A two-factor analysis of variance showed no evidence of conditioning without awareness; in fact, the blink rate for reinforcement periods was significantly less than the rate for base periods (p < .05). The anomaly was explained in terms of the effects of cognitive activity on eye-blink rate..