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  • Reinforcer magnitude and rate dependency: evaluation of resistance-to-change mechanisms.

Reinforcer magnitude and rate dependency: evaluation of resistance-to-change mechanisms.

Behavioural pharmacology (2014-08-15)
Jonathan W Pinkston, Brett C Ginsburg, Richard J Lamb
ABSTRACT

Under many circumstances, reinforcer magnitude appears to modulate the rate-dependent effects of drugs such that when schedules arrange for relatively larger reinforcer magnitudes rate dependency is attenuated compared with behavior maintained by smaller magnitudes. The current literature on resistance to change suggests that increased reinforcer density strengthens operant behavior, and such strengthening effects appear to extend to the temporal control of behavior. As rate dependency may be understood as a loss of temporal control, the effects of reinforcer magnitude on rate dependency may be due to increased resistance to disruption of temporally controlled behavior. In the present experiments, pigeons earned different magnitudes of grain during signaled components of a multiple FI schedule. Three drugs, clonidine, haloperidol, and morphine, were examined. All three decreased overall rates of key pecking; however, only the effects of clonidine were attenuated as reinforcer magnitude increased. An analysis of within-interval performance found rate-dependent effects for clonidine and morphine; however, these effects were not modulated by reinforcer magnitude. In addition, we included prefeeding and extinction conditions, standard tests used to measure resistance to change. In general, rate-decreasing effects of prefeeding and extinction were attenuated by increasing reinforcer magnitudes. Rate-dependent analyses of prefeeding showed rate-dependency following those tests, but in no case were these effects modulated by reinforcer magnitude. The results suggest that a resistance-to-change interpretation of the effects of reinforcer magnitude on rate dependency is not viable.

MATERIALS
Product Number
Brand
Product Description

Haloperidol, European Pharmacopoeia (EP) Reference Standard
Sigma-Aldrich
Clonidine hydrochloride, solid
Sigma-Aldrich
Haloperidol, powder
Clonidine hydrochloride, European Pharmacopoeia (EP) Reference Standard
Supelco
Benzoylecgonine-d3 solution, 100 μg/mL in methanol, ampule of 1 mL, certified reference material, Cerilliant®
Haloperidol for peak identification, European Pharmacopoeia (EP) Reference Standard
Haloperidol for system suitability, European Pharmacopoeia (EP) Reference Standard
Supelco
Benzoylecgonine-d3 solution, 1.0 mg/mL in methanol, ampule of 1 mL, certified reference material, Cerilliant®
USP
Haloperidol, United States Pharmacopeia (USP) Reference Standard
Supelco
Morphine sulfate salt solution, 1.0 mg/mL in methanol, drug standard