Impression valence constrains social explanations: the case of discounting versus conjunction effects.

Discounting refers to a reduction in explanation plausibility in light of another explanation, whereas conjunction effects refer to an increase in plausibility of explanations judged in combination rather than in isolation. Explanation compatibility moderates these effects, such that discounting is greater for incompatible explanations and conjunction effects are greater for compatible explanations. Three experiments examined whether this effect reflects perceptions regarding (a) the prior statistical association of causal factors, (b) the sharing of common causal mechanisms, or (c) coherence with regard to global impressions. Results indicated that impression valence predicts and also directly influences discounting and conjunction effects independent of covariation and mechanism, underscoring the pervasive impact of impressions on attributions.