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.

中文翻译：

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分析自发性高血压 (SHR) 和 wistar 京都 (WKY) 大鼠的幅度效应

我们分析了自发性高血压 (SHR) 和 Wistar 京都 (WKY) 大鼠在并发链程序的初始环节中在较小的食物 (SSF) 和较大的食物 (LLF) 之间进行选择的幅度效应。SSF 在一个终端链路中立即交付，而 LLF 在另一个终端链路中延迟了 0.01、5、10、20、40 或 80 秒。ABABA 设计改变了食物量，在条件 A 和 B 中分别为 1 对 4 和 3 对 8 食物颗粒。SHR 比 WKY 做出了更多的冲动选择。双曲衰减模型和广义匹配法很好地拟合了数据。SHR 在条件 A 中所做选择的贴现率 (k) 和贴现曲线下面积 (AUC) 与条件 B 中的相同。对于单个 WKY 所做的选择，