Perceptual and conceptual expertise mediate the verbal overshadowing effect in a training paradigm.

摘要

In the verbal overshadowing effect, persons who describe their memory of a stimulus often show impaired recognition. In the prototypical experiment, persons who see a difficult-to-describe stimulus (e.g., a face) and describe it from memory are less likely to correctly identify the face in a line-up than persons who did not describe the face. Previous studies suggest that verbal overshadowing is occurs when persons have substantially more perceptual than conceptual experience with the stimuli. However, the evidence for this hypothesis has been indirect and correlational. The purpose of this dissertation was to experimentally induce both verbal overshadowing and its opposite, verbal enhancement, by differentially training participants in a domain. Participants were given either No Training, Perceptual, or Conceptual Training: In Perceptual training they engaged in a task in which they briefly viewed and categorized 42 mushrooms by genus. The Conceptual training consisted of a videotaped lecture about mushroom structure and morphological features. Subjects then either described or did not describe from memory a target mushroom and were then given a recognition test for the target. The key predictions were that: (1) Untrained participants would show no significant effect of verbalization (i.e., no difference in recognition accuracy between those who did and did not describe mushrooms from memory; (2) that Perceptually trained participants would be subject to the verbal overshadowing effect; and (3) that Conceptual training would confer a benefit of verbalization.; Experiment 1 confirmed the first two predictions but failed to obtain the predicted benefit of verbalization in the conceptual training condition. The training sessions were modified in Experiment 2 in order to try to strengthen the previously obtained verbal overshadowing effect and to try to obtain the predicted verbal enhancement. Experiment 2's results were consistent with the original predictions: No verbal overshadowing among nontrained controls, verbal overshadowing for perceptually-trained participants and verbal enhancement for conceptually-training participants. In addition to solidifying theoretical understanding of the verbal overshadowing effect and of learning in complex domains, the results may be relevant to the structuring of training materials in domains that have prominent perceptual and conceptual components (e.g., medicine, the arts, etc).