Contingent reinforcement for reduced breath carbon monoxide levels: target-specific effects on cigarette smoking.

This study determined the effects on smoking behavior of providing contingent reinforcement for nonsmoking versus reduced smoking afternoon breath carbon monoxide (CO) target levels. Twenty-eight hired chronic smoker volunteers were randomly assigned to one of three experimental conditions during a 10-day intervention: (a) 8 ppm target CO, $5 per day incentive (n = 11); (b) 16 ppm target CO, $4 per day incentive (n = 8); or (c) 8 ppm target CO, no incentive (n = 9). Both payment groups showed significantly lower CO levels and greater amounts of daytime smoking reduction than the no-pay group. A specific effect of CO target was also seen; 45% of subjects in the 8 ppm group compared with 0% of subjects in the 16 ppm target and no-pay groups produced average afternoon CO levels of 8.5 ppm or lower during the intervention. Average levels of CO and smoking reduction did not differ for the two paid groups, however, because some subjects in the 8 ppm group failed to reduce CO sufficiently to contact the reinforcer. Contingent reinforcement based on expired air CO levels can exercise powerful and precise (target-specific) control over smoking behavior, but there may be individual differences in ability to meet reinforcement contingencies if difficult targets are introduced abruptly.