Integration of the ecological and error models of overconfidence using a multiple-trace memory model.

A memory processes account of the calibration of probability judgments was examined. A multiple-trace memory model, Minerva-Decision Making (MDM; M. R. P. Dougherty, C. F. Gettys, & E. E. Ogden, 1999), used to integrate the ecological (Brunswikian) and the error (Thurstonian) models of overconfidence, is described. The model predicts that overconfidence should decrease both as a function of experience and as a function of encoding quality. Both increased experience and improved encoding quality result in lower variance in the output of the model, which in turn leads to improved calibration. Three experiments confirmed these predictions. Implications of MDM's account of overconfidence are discussed.

Averaging expectancies and perceptual experiences in the assessment of quality.

This study examines whether people integrate expectancy information with perceptual experiences when evaluating the quality of consumer products. In particular, we investigate the following three questions: (1) Are expectancy effects observed in the evaluation of consumer products? (2) Can these effects be viewed in cognitive processing terms? (3) Can a mathematical model based on the averaging of attribute information describe the effects? Participants in two experiments blindly evaluated (with the product names removed) consumer products from six sensory modalities: vision (computer printer output), tactile (paper towels), olfaction (men's cologne), taste (corn chips), auditory (audio cassette tapes), and tactile/medicinal (hand lotion). Participants in both experiments were asked to: (1) rate the overall quality of the product given arbitrary quality labels (High Quality, Medium Quality, or Low Quality); (2) rate the overall quality of the product without the labels, and (3) estimate the scale values for the quality labels alone. Group results revealed main effects of the quality labels in all product categories. The pattern of results could be described by an averaging model based on Information Integration Theory. These results have implications for placebo effects in consumer behavior and decision making.