Abstract

A method is presented for deciding whether correct predictions about other people are based on simulation or theory use. The differentiating power of this method was assessed with cognitive estimation biases (e.g. estimating the area of Brazil) in two variations. Experiments 1 and 2 operated with the influence of response scales of different length. Experiment 3 used the difference between free estimates that tended to be far off the true value and estimates constrained by an appropriate response scale, where estimates became greatly more realistic. The critical question is how well observer subjects can predict these target biases under two different presentation conditions. Response scale biases (Experiments 1 and 2) were more strongly predicted when observer subjects were presented with the two scales juxtaposed, than when responses for each scale were given independently. This speaks for the use of a theory, since simulation should, if there is any difference at all, be made more difficult by the juxtaposition of conditions. The difference between free and constrained estimations (Experiment 3) was more strongly predicted under independent than under juxtaposed presentation. This speaks for the use of simulation since use of a theory should, if anything, be helped by juxtaposition of problems since it helps highlight the theoretically relevant factor. Results are discussed in view of recent proposals about when simulation is likely to be used, i.e. for belief fixation but not action prediction (Stich and Nichols, 1995b), for content fixation (Heal, 1996a), and for rational effects only (Heal, 1996b).