Flaherty C F, Rowan G A
J Exp Psychol Anim Behav Process. 1986 Oct;12(4):381-93.
Contrast effects were obtained in rats in the consumption of saccharin solutions in three different paradigms. Degree of negative contrast varied as a function of concentration disparity, but not equally in the three procedures. Successive negative contrast occurred following shifts from 0.15% to either 0.075% or 0.05% saccharin but did not occur following shifts to 0.10% or 0.125% saccharin. Some degree of simultaneous contrast was obtained with all four concentration disparities. Anticipatory contrast, where the intake of the first substance is suppressed by a more preferred second substance, occurred only in the case of the 0.05%-0.15% difference in concentrations. It was suggested that the several contrast paradigms engage somewhat different psychological processes differentially involving emotional, sensory, and associative mechanisms, but all lead to behavior based on relative value. A modification of Toates's (1981) incentive model of ingestive behavior was suggested to incorporate relativity effects based on both associative and nonassociative factors in the consumption of both nutritive and nonnutritive substances.
在三种不同范式下，研究人员在大鼠摄入糖精溶液的过程中获得了对比效应。负对比的程度随浓度差异而变化，但在这三种实验程序中变化并不相同。从0.15%的糖精溶液转换到0.075%或0.05%的糖精溶液后会出现连续负对比，但转换到0.10%或0.125%的糖精溶液后则不会出现。对于所有四种浓度差异，都获得了一定程度的同时对比。预期对比（即第一种物质的摄入量会被更偏好的第二种物质抑制）仅在浓度差异为0.05%-0.15%的情况下出现。研究表明，几种对比范式涉及一些不同的心理过程，不同程度地涉及情绪、感觉和联想机制，但所有这些都导致基于相对价值的行为。有人建议对托茨（1981年）的摄食行为动机模型进行修改，以纳入在营养和非营养物质消费中基于联想和非联想因素的相对性效应。
