EFFECT OF REINFORCER MAGNITUDE ON PERFORMANCE MAINTAINED BY PROGRESSIVE-RATIO SCHEDULES

• Published in: Journal of the experimental analysis of behavior Vol. 91; no. 1; pp. 75 - 87
• Main Authors: Rickard, J.F., Body, S., Zhang, Z., Bradshaw, C.M., Szabadi, E.
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01.01.2009; Society for the Experimental Analysis of Behavior; Society for the Experimental Analysis of Behavior, Inc
• Subjects: Animals; Behavior; Conditioning, Operant; Correlation; Experiments; Feedback (Response); Female; Foreign Countries; Incentives; lever press; Mathematical Principles of Reinforcement (MPR); progressive-ratio schedule; Psychotropic drugs; rat; Rats; Rats, Wistar; Reaction Time; Reinforcement; Reinforcement Schedule; Reinforcement, Psychology; reinforcer magnitude; Response Rates (Questionnaires); United Kingdom; United Kingdom
• ISSN: 0022-5002; 1938-3711
• DOI: 10.1901/jeab.2009.91-75

This experiment examined the relationship between reinforcer magnitude and quantitative measures of performance on progressive‐ratio schedules. Fifteen rats were trained under a progressive‐ratio schedule in seven phases of the experiment in which the volume of a 0.6‐M sucrose solution reinforcer was varied within the range 6–300 μl. Overall response rates in successive ratios conformed to a bitonic equation derived from Killeen's (1994) Mathematical Principles of Reinforcement. The “specific activation” parameter, a, which is presumed to reflect the incentive value of the reinforcer, was a monotonically increasing function of reinforcer volume; the “response time” parameter, δ, which defines the minimum response time, increased as a function of reinforcer volume; the “currency” parameter, b, which is presumed to reflect the coupling of responses to the reinforcer, declined as a function of volume. Running response rate (response rate calculated after exclusion of the postreinforcement pause) decayed monotonically as a function of ratio size; the index of curvature of this function increased as a function of reinforcer volume. Postreinforcement pause increased as a function of ratio size. Estimates of a derived from overall response rates and postreinforcement pauses showed a modest positive correlation across conditions and between animals. Implications of the results for the quantification of reinforcer value and for the use of progressive‐ratio schedules in behavioral neuroscience are discussed.