Commitment to a developing preference and predecisional distortion of information

People tend to distort their evaluation of decision-relevant information in favor of the currently preferred alternative. We test whether this predecisional distortion of information is amplified by increased commitment to that current preference. We manipulated commitment, without changing the preferred option’s content, by requiring participants to indicate their preference either by circling or by darkening a sizable box (cf. feature-positive effect). Experiment 1 revealed that the effort to darken substantially increased predecisional distortion. Experiment 2 ruled out elaboration as an explanation for the effect of darkening. Experiment 3 showed that, among participants who attributed the darkening effort to an external source, predecisional distortion decreased when the source was believed to summon effort. These findings suggest that the developing commitment to a tentatively preferred alternative is one driver of predecisional distortion.