Abstract
People can learn sensorimotor contingencies between hand movements and color perception (Richters & Eskew, 2007) which produce changes in subsequent color judgments that are dependent on the hand movements. These experiments include a pre-test, a learning phase, and a post-test. In the learning phase, we correlated leftward hand movements (using a joystick) and presentation of a high-contrast red spot, and rightward hand movements and a green spot. In each learning trial, observers heard five color names (e.g., “red”, “red”, “green”, “red”, “green”), and then produced that sequence of colors on the screen by moving the joystick to the appropriate sides. We found that 45 minutes of learning trials produced a shift in color judgments in the post-test: observers compared near-threshold colors of the spots, which varied around white, by judging if the second spot was “redder” or “greener” than the first spot (cf. Bompass & O'Regan, 2006). However, this effect could be linguistic rather than sensory — a pairing between hand-movements and the words “red” and “green,” which influenced the color judgments later. The present study substituted the words “left” and “right” for the color name words used previously in the learning phase. This linguistic change had no effect on the results, showing that the change in color judgments is not just a shift in color naming. Instead, the effect is caused by learning a new sensorimotor contingency between a color percept and a hand movement, and then compensating for that contingency. We also examine detection thresholds from red and green spots, paired with leftward and rightward hand movements, to see if the effect can be obtained at threshold and to test whether the effect is best characterized as a shift in criterion or sensitivity. Both explanations will be discussed along with related experiments.