Choice, changeover, and travel

Since foraging in nature can be viewed as instrumental behavior, choice between sources of food, known as “patches,” can be viewed as choice between instrumental response alternatives. Whereas the travel required to change alternatives deters changeover in nature, the changeover delay (COD) usually deters changeover in the laboratory. In this experiment, pigeons were exposed to laboratory choice situations, concurrent variable-interval schedules, that were standard except for the introduction of a travel requirement for changeover. As the travel requirement increased, rate of changeover decreased and preference for a favored alternative strengthened. When the travel requirement was small, the relations between choice and relative reinforcement revealed the usual tendencies toward matching and undermatching. When the travel requirement was large, strong overmatching occurred. These results, together with those from experiments in which changeover was deterred by punishment or a fixed-ratio requirement, deviate from the matching law, even when a correction is made for cost of changeover. If one accepted an argument that the COD is analogous to travel, the results suggest that the norm in choice relations would be overmatching. This overmatching, however, might only be the sign of an underlying strategy approximating optimization.     

Foraging in a simulated natural environment: There's a rat loose in the lab

Rats were required to earn their food in a large room having nine boxes placed in it, each of which contained food buried in sand. In different phases of the experiment the amount of time allowed for foraging, the amount of food available in each food patch, and the location of the different available amounts were varied. The rats exhaustively sampled all patches each session but seemed to have fairly strong preferences for certain locations over others. If position preferences were for patches containing small amounts of food, the sensitivity to amount available was increased so that when location was compensated for, a pattern of optimal foraging was evident. The importance of environmental constraints in producing optimal behavior and the relation of the observed behavior to laboratory findings are discussed.     

Choice and multiple reinforcers

Pigeons chose between equivalent two-component mixed and multiple terminal-link schedules of reinforcement in the concurrent-chains procedure. The pigeons preferred the multiple schedule over the mixed when the components of the compound schedules were differentiated in terms of density of reinforcement, but the pigeons were indifferent when the components were differentiated in terms of number of reinforcers per cycle. Taken together, these results indicate that a local variable, the interval to the first reinforcer, but not a molar variable, the number of reinforcers, was sufficient to differentiate the components and thereby evoke preference.     

Effects of fixed-ratio sample and choice response requirements upon oddity matching

Three pigeons were trained on oddity matching in which either 1, 4, 8, 16, or 32 sample-key observing responses were required to turn off the sample stimuli and turn on the comparison stimuli. Oddity accuracy increased when the observing-response requirement was raised and decreased when the requirement was lowered. Next, while the observing requirement was maintained at one response, the number of responses required to the comparison stimuli was either 1, 4, 8, 16, or 32. Under these conditions, choice was defined as the comparison that first accumulated the required number of responses. In general, increasing the comparison-response requirement decreased accuracy and lowering the comparison requirement increased accuracy. The fixed-ratio observing requirements appeared to facilitate control by stimuli serving an instructional function.     

Effects of food deprivation and reinforcement magnitude on conditioned suppression

In Experiment I, the responding of rats lever pressing on a variable-interval schedule for sucrose solution was partially suppressed by a variable duration conditioned stimulus followed by shock. When food deprivation was increased, response rates during and before the conditioned stimulus increased monotonically. Varying the concentration of sucrose across blocks of sessions or from session to session in a semi-random sequence had little effect on response rates either before or during the conditioned stimulus. With a fixed sequence of increasing concentrations across a five-session block, increased concentration produced much more rapid increases in response rates before than during the conditioned stimulus. In Experiment II, rats were presented with the same sequence of increasing concentrations across a five-session block. When tested at 80% body weight, response rates increased rapidly as concentration increased, but at 100%, body-weight rates increased only slightly. The effect of a change in body weight in Experiment II thus mimicked the effect of the conditioned stimulus in the latter part of Experiment I. These findings support the view that the effect of a pre-aversive conditioned stimulus is similar to that of a change in food deprivation, but unlike that of a change in reinforcement magnitude.     

The effect of rearing environments on the contrafreeloading phenomenon in rats

Eight naive rats were reared in enriched or impoverished environments for 39 days after weaning and then lived in operant chambers, in which they could obtain food pellets freely or by lever pressing, for 25 or 30 days. The animals raised in an impoverished environment acquired the bar-press response quickly when placed in the operant chambers and maintained a preference for obtaining food via bar pressing. Animals raised in an enriched environment did not learn to lever press, as demonstrated by low levels of responding and the lack of bar pressing when free food was subsequently removed. It was concluded that restricting animals' postweaning environments facilitated learning in a choice situation, probably because of increased activity levels. The results are interpreted in relation to previous studies on rearing environments and on contrafreeloading.     

消费者基于选择集的情境效应

消费者基于选择集的情境效应颠覆了传统的理性选择理论,表明了情境对消费者偏好和选择的系统性影响。情境效应主要的类型有吸引效应和折衷效应。情境效应具有感知偏差、风险和负面情绪规避以及信息推理等方面的内在机理。选择集结构和特征及消费者等因素都对情境效应产生影响,而情境效应会影响消费者偏好的构建。未来情境效应研究将会向复杂属性组合、复杂购买情境和新情境效应的发现等方面拓展。     

风险决策过程验证：补偿/非补偿模型之争的新认识与新证据

风险决策是人类赖以生存和发展的重大决策。如何进行风险决策是人类不断认识和改造世界过程中遇到的未解之谜。主流风险理论认为, 风险决策是一个补偿性的、期望值最大化的过程; 而非主流的风险理论则认为, 风险决策是非补偿性的, 并不遵循期望法则所假设的加权求和等过程。这一谜团为何一直没有得以破解, 或许是因为我们未找到揭示其心理过程的令人信服的证据。近10年来, 我们针对风险决策过程, 借助行为实验、眼动记录法、事件相关电位、功能磁共振成像等技术, 系统探索风险决策的心理和神经机制, 为回答“风险决策是否遵循补偿性规则”这一问题提供了汇聚性证据。本文依据期望法则所假设的概率函数推导、加权过程、加权求和过程、总分最大化等步骤, 对这些研究进行梳理与回顾, 以期加深人们对风险决策机制的理解, 并为建立、健全与风险决策相关的政策、法律法规提供理论依据。     

厌恶和恐惧情绪对跨期选择的不同影响：基于ERP的研究

本研究运用事件相关电位技术(ERPs)考察厌恶和恐惧情绪对跨期选择的影响。其中,厌恶和恐惧情绪采用情绪面孔图片进行启动,分析跨期选择任务中评估阶段所诱发的ERP成分。行为结果发现,与中性面孔相比,厌恶面孔启动使个体倾向于选择立即奖赏。ERP结果发现,在选项评估阶段,厌恶面孔比中性和恐惧面孔启动诱发更大的P2、P3和LPP波幅。这说明,厌恶情绪促使个体投入更多的注意和动机资源对跨期选项进行评估,进而使个体倾向即时满足。     

整合模型还是占优启发式模型? 从齐当别模型视角进行的检验

实验从齐当别模型的视角,通过对决策过程反应时的考察分别对以累积预期理论(cumulative prospect theory)为代表的整合模型和启发式模型家族的重要成员--占优启发式模型(priority heuristic)--进行检验。结果表明,决策过程反应时并未随着占优启发式模型所假定的决策步骤的增加而变慢;也未随着选项之间整体值差值的变大而变快;模糊决策过程的反应时反而快于风险决策过程的反应时。无论是以累积预期理论为代表的整合模型还是占优启发式模型均不能满意地描述和解释人们的实际决策过程,而齐当别模型则能解释大部分实验结果。文章建议多角度、多指标探讨人们的决策过程,检验、修改、完善,以及建立新的启发式模型或决策过程模型(process model),以增进对人们如何进行风险决策的理解。