A neuropsychological dimension for anchoring effects

Previous research has shown that strength of handedness predicts differences in sensory illusions, Stroop interference, episodic memory, and beliefs about body image and the origin of species. Recent evidence also suggests handedness differences in the susceptibility to information framing and persuasion. The present paper extends this line of work to decision anchoring effects. In Experiment 1, 131 introductory psychology students responded to 12 real-world knowledge questions after being given random, uninformative high or low anchors. Results indicated that "strong-handers" showed larger anchoring effects than "mixed-handers." In Experiment 2, 89 introductory psychology students responded to 6 real-world knowledge questions in a modified, two-step anchoring task in which participants were given a credible source for the anchored information and asked to give pre- and post-anchor estimates. In contrast to Experiment 1, results revealed that mixed- and strong-handers were affected similarly by anchoring. In Experiment 3, 158 students were asked to estimate the answer to one of two versions of 8! (8 x 7 x 6 x 5 x 4 x 3 x 2x 1 or 1 x 2 x 3 x 4 x 5 x 6 x 7 x 8)-a multiplication problem in which the high and low anchors are inherently informative. Here, mixedhanders showed larger anchoring effects than strong-handers. A theory centered around the notion of hemispheric specialization and the communication between the two halves of the brain as well as arguments about the informativeness of anchors, metacognition, and recent theorizing in the anchoring literature are used to account for these data. Copyright (c) 2005 John Wiley & Sons, Ltd.