Handedness Differences in Belief Updating

University Of Toledo, Toledo OH

Investigators

Abstract

Previous research in decision making has identified a number of decision making "biases" or heuristics. For example, in a classic study of attribute framing (Levin & Gaeth, 198), ground beef labeled as "75% lean" (the positive frame) was seen as better tasting and less greasy than the same meat labeled as "25% fat" (the negative frame). Research has also shown that not everyone is susceptible to these biases. The question one might ask is why? Is there a set of underlying principles that can describe this observed behavior? More importantly, are there individual difference factors that can predict why some decision makers show these effects and other do not? Very recent research has attempted to answer this question using stable person characteristics such as cognitive abilities and predispositions, personality traits, and societal/cultural differences. While such indices have provided some insight, the answer may be even more fundamental than heretofore presented. Specifically, there may be a neuropsychological explanation for why some people respond to information and others do not, and why some (but not all) people respond quite differently to somewhat different forms of the same information. That is, there may be a strong link between decision processing and brain organization. The central hypothesis of the proposed research is that strength of handedness, which relates to left brain-right brain interconnectivity, may be a very good and generalizable predictor of decision making style. Preliminary evidence supporting this idea has been found in our lab via two recent studies, one in the area of persuasion and the other in a more traditional decision making task where pregnant women (after being told there is a 1%-3% chance of giving birth to an abnormal baby OR there is a 97%-99% chance of giving birth to a normal baby) gave risk estimates of giving birth to a baby with a birth defect. Interestingly, belief updating and the usual framing effect were demonstrated, but only in "mixed-handers" not "strong-handers." A series of other studies is proposed which attempt to replicate some of the simpler and more robust studies demonstrating decision "biases" using handedness as the predictor of susceptibility to these effects. These biases include risky choice and goal framing, anchoring and adjustment, and the attraction (or decoy) effect. This work, which combines cognitive neuropsychology and decision making, may advance our understanding and theorizing about decision behavior. It will permit the refinement of theoretical models of decision making such as the "adaptive decision maker" (Payne, Bettman, and Johnson, 1993). It will also help us to better understand belief formation and decision making in everyday life across a variety of decision tasks and individuals.