Analyzing the magnitude effect in spontaneously hypertensive (SHR) and wistar Kyoto (WKY) rats

•Preference changed within a delay component and among delay components.•The SHRs made more impulsive choices in conditions A and B than the WKYs.•Discounting rates in conditions A were like those in conditions B.•Sensitivity to the immediacy of reinforcement was slightly higher in conditions A.•We...

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Bibliographic Details
Published in:Behavioural processes 2020-12, Vol.181, p.104258-104258, Article 104258
Main Authors: Aparicio, Carlos F., Malonson, Malana, Hensley, Jason
Format: Article
Language:English
Subjects:
Animals
Choice
Delay discounting
Impulsive Behavior
Magnitude effect
Rats
Rats, Inbred SHR
Rats, Inbred WKY
SHR
WKY
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Summary:•Preference changed within a delay component and among delay components.•The SHRs made more impulsive choices in conditions A and B than the WKYs.•Discounting rates in conditions A were like those in conditions B.•Sensitivity to the immediacy of reinforcement was slightly higher in conditions A.•We found no compelling evidence either supporting or discarding the magnitude effect. We analyzed the magnitude effect in Spontaneously Hypertensive (SHR) and Wistar Kyoto (WKY) rats choosing between a smaller-sooner (SSF) and a larger-later food (LLF) in the initial link of a concurrent-chains procedure. The SSF was delivered immediately in one terminal link and the LLF delayed 0.01, 5, 10, 20, 40, or 80 s in the other terminal link. An ABABA design varied food amount, 1 vs. 4 and 3 vs. 8 food-pellets in conditions A and B, respectively. The SHRs made more impulsive choices than the WKYs. The hyperbolic-decay model and the Generalized Matching Law fitted the data well. Discounting rate (k) and the area under the discounting curve (AUC) for the choices made by the SHRs in conditions A, were like those in conditions B. For the choices that the individual WKYs made, k was slightly higher and AUC smaller in conditions B than in conditions A. For both strains sensitivity to the immediacy of the LLF (s) was slightly higher in conditions A than in conditions B. Thus, we found no conclusive, compelling evidence either supporting or discarding the magnitude effect in the SHRs and scarce evidence supporting an effect opposite to the magnitude effect in the WKYs.
ISSN:0376-6357
1872-8308
DOI:10.1016/j.beproc.2020.104258