Determinants of collective behavior, as suggested by the social identity or self-categorization approach and social movement research, were examined in 2 field studies. Study 1 was conducted in the context of the older people's movement in Germany and Study 2 in the context of the gay movement in the United States. Both studies yielded similar results pointing to 2 independent pathways to willingness to participate in collective action; one is based on cost-benefit calculations (including normative considerations), and the other is based on collective identification as an activist. Study 2 included an experimental manipulation and provided evidence for the causal role of collective identification as an activist. Directions for future research on the proposed dual-pathway model are suggested.

are gratefully acknowledged. Correspondence concerning this manuscript should be addressed via email to:kf@psychologie.uni-heidelberg.de. AbstractThe term pseudocontingency (PC) denotes the logically unwarranted inference of a Pseudocontingencies 2 contingency between two variables X and Y from information other than pairs of x i , y i observations, namely, the variables' univariate baserates as assessed in one or more ecological contexts. We summarize recent experimental evidence, showing that PCs can play a pivotal role in many areas of judgment and decision making. We argue that the exploitation of the informational value of baserates underlying PCs offers an alternative perspective on many phenomena in the realm of adaptive cognition that have been studied in isolation so far.Although PCs can lead to serious biases under some conditions, they afford an efficient strategy for inductive inference making in probabilistic environments that render baserate information, rather than genuine covariation information, readily available. Adaptive behavior hinges on our ability to extract meaningful regularities from the flood of information provided by the physical and social environment. In an uncertain world, discerning regularities often amounts to assessing statistical contingencies between two variables over a series of events, such as correlations between causes and events, signals and significant events, predictions and feedback, actions and consequences, or behaviors associated with particular personality types. It is no exaggeration to claim that the ability to assess contingencies is crucial for adaptive learning and behavior, for rational action and decision making, and -ultimately -for survival in a risky and uncertain world. Thus, contingency assessment is commonly considered a major module of inductive intelligence, as stated in several pertinent reviews (Allan, 1993;Allan, Hannah, Crump & Siegel, 2008;Alloy & Tabachnik, 1984;Arieh & Algom, 2002;Crocker, 1981;Fiedler, 2000).In this article, we present an alternative perspective on inductive learning, drawing on pseudocontingencies rather than contingencies proper. The major claim we will put forward is that when organisms figure out correlations or contingencies (in case of nominally scaled variables), they often engage in a cognitive inference process that is sensitive to something different from a genuine correlation. To start with a definition, the term "pseudocontingency" denotes the (logically unwarranted) inference of a contingency between two variables X and Y from information other than pairs of x i , y i observations. In empirical reality, there are many situations in which joint observations of two or more variables are not available, or in which environmental or mnemonic constraints preclude the use of such genuine contingency information. In these situations, pseudocontingencies (PCs) can be inferred from other information, particularly, from the covariation of unequal baserates of high and low levels of X and Y over an ecological context fact...

In 3 experiments, the authors explored a contingency illusion termed pseudocontingency (PC) that produces logically unwarranted but potentially useful inferences. PCs arise when bivariate contingencies are inferred from univariate distributions via heuristic alignment processes. For example, in the absence of information about the co-occurrence of TV habits and aggressive behavior within a school class, when the prevalence of both attributes is high, a teacher may infer a positive PC as if students who often watch TV were highly aggressive. Throughout 3 experiments, predictions of the level of 1 variable from the level of another served as a measure of PCs. The illusion could be evoked reliably whether information about target attributes was presented successively or simultaneously, whether common-cause or common-effect models were activated, and whether attributes involved 2 or more levels. The discussion centers on the cognitive processes underlying PCs and their origin and adaptive value.

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The pseudocontingency (PC) illusion is investigated in a simulated classroom setting. Related to the notion of ecological correlations, PCs arise when the assessment of contingencies at the individual level is affected by the base-rate relations at the group level. Positive PCs arise when base rates of 2 variables are skewed in the same direction (e.g., high ability and high motivation), whereas negative PCs arise when base rates are skewed in opposite directions. Experiment 1 demonstrates that PCs between student ability and motivation are contingent on effective base-rate assessment at the group level, with a bias toward positive PCs reflecting prior expectancies. Ruling out prior expectancies, Experiment 2 yields symmetric positive and negative PCs. Experiment 3 provides evidence for PC effects on gender stereotypes. Finally, Experiment 4 extends PCs from group base rates to individual student base rates, ruling out an explanation in terms of capacity deficits or inability to assess individuating information.