Perceptual Learning vs. Context-Sensitive Retrieval: Why do people judge green lines to be shorter/longer than red lines of the same length? Do they perceive them differently or do they retrieve a biased set of alternatives in their comparison set?

The mechanisms of perceptual learning and contextually sensitive retrieval were recently suggested as possible explanations of the effect of irrelevant information on judgment: the judgment of the same stimulus was reported to depend on its irrelevant characteristics. The reported experiments test the chances for a perceptual learning explanation of the effect. Experiment 1 successfully induces the effect of irrelevant dimension in judgment of line lengths, while Experiment 2, performed immediately after the first experiment, tests the possibility that the perceptual learning mechanisms have led to a “rerepresentation” of the line length depending on its color and thus the participants will actually see the red lines as shorter/longer then the red ones. Since Experiment 2 failed to demonstrate any significant difference in perception of the stimulus length depending on its color, the possibility that perceptual learning mechanisms underlie the effect of irrelevant dimension was not empirically supported for the moment.