Persistence of Causal Illusions After Extensive Training

Bayesian hypothesis testing presents an attractive alternative to p value hypothesis testing. Part I of this series outlined several advantages of Bayesian hypothesis testing, including the ability to quantify evidence and the ability to monitor and update this evidence as data come in, without the need to know the intention with which the data were collected. Despite these and other practical advantages, Bayesian hypothesis tests are still reported relatively rarely. An important impediment to the widespread adoption of Bayesian tests is arguably the lack of user-friendly software for the run-of-the-mill statistical problems that confront psychologists for the analysis of almost every experiment: the t-test, ANOVA, correlation, regression, and contingency tables. In Part II of this series we introduce JASP (http://www.jasp-stats.org), an open-source, cross-platform, user-friendly graphical software package that allows users to carry out Bayesian hypothesis tests for standard statistical problems. JASP is based in part on the Bayesian analyses implemented in Morey and Rouder’s BayesFactor package for R. Armed with JASP, the practical advantages of Bayesian hypothesis testing are only a mouse click away.

How are humans' subjective judgments of contingencies related to objective contingencies? Work in social psychology and human contingency learning predicts that the greater the frequency of desired outcomes, the greater people's judgments of contingency will be. Second, the learned helplessness theory of depression provides both a strong and a weak prediction concerning the linkage between subjective and objective contingencies. According to the strong prediction, depressed individuals should underestimate the degree of contingency between their responses and outcomes relative to the objective degree of contingency. According to the weak prediction, depressed individuals merely should judge that there is a smaller degree of contingency between their responses and outcomes than nondepressed individuals should. In addition, the present investigation deduced a new strong prediction from the helplessness theory: Nondepressed individuals should overestimate the degree of contingency between their responses and outcomes relative to the objective degree of contingency. In the experiments, depressed and nondepressed students were present with one of a series of problems varying in the actual degree of contingency. In each problem, subjects estimated the degree of contingency between their responses (pressing or not pressing a button) and an environmental outcome (onset of a green light). Performance on a behavioral task and estimates of the conditional probability of green light onset associated with the two response alternatives provided additional measures for assessing beliefs about contingencies. Depressed students' judgments of contingency were surprisingly accurate in all four experiments. Nondepressed students, on the other hand, overestimated the degree of contingency between their responses and outcomes when noncontingent outcomes were frequent and/or desired and underestimated the degree of contingency when contingent outcomes were undesired. Thus, predictions derived from social psychology concerning the linkage between subjective and objective contingencies were confirmed for nondepressed students but not for depressed students. Further, the predictions of helplessness theory received, at best, minimal support. The learned helplessness and self-serving motivational bias hypotheses are evaluated as explanations of the results. In addition, parallels are drawn between the present results and phenomena in cognitive psychology, social psychology, and animal learning. Finally, implications for cognitive illusions in normal people, appetitive helplessness, judgment of contingency between stimuli, and learning theory are discussed.