EVENT CONTROLLABILITY IN COUNTERFACTUAL THINKING

The counterfactual assessment of events, i.e. is the mental construction of alternatives to factual events, is a pervasive mental process that is quite natural for people. For example, people easily make counterfactual statements when reflecting on dramatic events ('If only I hadn't drunk alcohol the night of the car accident...'). The way in which people select the events to mutate when requested to undo a scenario outcome seems to be governed by general rules. One is that subjects tend to select exceptional (i.e. unusual or surprising) rather than normal events (Kahneman and Tversky 1982a,b; Kahneman and Miller 1986). Another is that subjects prefer to select the first rather than the subsequent events in a causal chain (Wells, Taylor and Turtle 1987). We hypothesized that events corresponding to controllable actions (i.e. voluntary decisions) by the protagonist of a scenario are more mentally mutable than events which occur in the surrounding background. In experiment 1, we manipulated the order and the controllability of four events in a scenario. Contrary to the causal order effect hypothesis, subjects preferred to change the event corresponding to a voluntary decision of the scenario actor, regardless of its relative position in the scenario. Experiment 2 showed that subjects made this choice regardless of the normal vs. exceptional status of the voluntary action event. Experiment 3 gave evidence that an unconstrained action performed by the focal actor of a story is more mutable than a constrained action performed by the same actor. The implications of these findings for the analysis of accidents involving human errors are discussed.