Animal studies on the meta choice behavior under uncertainty

“元”选择是在两种选择情境之间进行的选择，每一种选择情境都由若干选择项组成。“自由”与“强迫”选择实验是元选择的恰当例子之一。在这样的实验中，被试在第一阶段选择两种情景中的一种，然后在第二阶段的自由选择情景中选择多个备选方案中的一个，或在第二阶段的强迫选择情景中强制选择单一备选方案。对任何替代方案的反应都会产生同样的结果。在项目1中，我们使用并发链计划在1996年的四只鸽子中测试了这种类型的元选择。尽管前人的研究结果表明，鸽子在通常的条件下更喜欢自由侧而不是强迫侧，但在延迟强化条件下和在自由选择条件下将灭绝时间表添加到其中一种选择的情况下，我们也没有发现这种一致的偏好。我们在1997年详细阐述了我们的步骤，如应用Stubbs&Pliskoff方法，并使用概率强化代替延迟强化。当强化概率(Pr)为1时，7只鸽子略偏爱自由侧，而当Pr不为1时，7只鸽子没有表现出一致的偏好。当自由选择情境中一种选择的Pr部分下降时，他们表现出风险厌恶。在项目2中，我们试图评估“对变化的抵抗力”，将其作为衡量备选方案之间偏好的一种新方法。与多链调度相比，只有多链调度具有更高的响应率和更强的抗VI变化能力。

A "meta" choice is a choice between two choice situations, each of which are consisted of some alternatives. The "free" versus "forced" choice experiment is one of appropriate examples of the meta choice. In such an experiment, subjects choose one of two situations in the first stage, then they choose one of multiple alternatives in the free choice situation or choose forcefully single alternative in the forced choice situation in the second stage. Responses to any alternatives result to the same outcomes. In Project 1, we used the concurrent-chains schedule for testing this type of the meta choice in four pigeons in 1996. Although previous results predicted that pigeons preferred the free to the forced side in the usual settings but not preferred the free side in some settings under delayd reinforcement, we could not find such consistent preference even in the delayd reinforcement condition and in the condition which added the extinction schedule to one of alternatives in the free choice situation. We elaborated our procedures in 1997, such as application of Stubbs & Pliskoff method, and used probabilistic reinforcement instead of delayd reinforcement. Seven pigeons preferred the free side a little if the reinforcement probability (Pr) was one, but showed no consistent preference if Pr was not one. They showed risk averse when Pr of one alternative in the free choice situation partly decreased. In Project 2, we tried to evaluate "resistance to change" as a new measure of preference between alternatives. Compared the concurrent-chains schedule to the multiple-chains schedule, both were consisted of FI and VI with same interval values, we observed higher response rate and stronger resistance to change in VI only in the latter schedule.