Abstract
Several recent studies of multiletter matching have included pairs of strings that have-the-same letters in different positions (rearranged pairs). The task can be defined such that these rearranged pairs are correctly classified asdifferent (i.e., subjects respond “same” only if the strings have the same letters in the same positions—the order task) or assame (i.e., subjects respond “same” if the strings have the same letters regardless of their positions—the item task). The order task produces left-to-right serial-position effects, whereas the item task produces U-shaped serial position effects. Because these differences suggest that subjects may be able to exert strategic control over the comparison process, two sets of experiments were designed to test whether or not subjects can change the relative weightings devoted to the respective serial positions. In Experiments 1 and 2, the probability that a mismatch occurred in the different positions was manipulated. In Experiments 3 and 4, the physical spacing between letters, as well as whether or not the spaces were filled with neutral noise characters, was varied. None of the manipulations had much influence on the serial-position effects. Thus, the distinct serial-position effects for the order and item tasks apparently are mandatory and not due-to-any voluntary-comparison strategy.
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This research was supported in part by Grant 88-0002 from the Cognition Program of the Air Force Office of Scientific Research to Auburn University and by United States Army Research Institute Contracts MDA 903-86-K-0 155 and MDA 903-90-K-0066 to the Institute of Cognitive Science at the University of Colorado.
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Proctor, R.W., Healy, A.F. & Van Zandt, T. Same—differentjudgments of multiletter strings: Insensitivity to positional bias and spacing. Perception & Psychophysics 49, 62–72 (1991). https://doi.org/10.3758/BF03211617
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DOI: https://doi.org/10.3758/BF03211617