Effect of Item Similarity on the Speed of Memory Search

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Chase and Posner reported to the Midwestern Psychological Association in 1965 their investigation of the speed with which subjects determined whether a target letter (TS) was present or not in a comparison set (CS) when the letters were drawn from an acoustically similar population (AC), a visually similar population (VIS) or a neutral population (N), and the stimuli were presented visually. TS was presented either simultaneously with CS (visual comparison search), or before CS (visual recognition search) or after CS (memory search). From the evidence that verbal material is coded auditorily in memory1,2 they anticipated that acoustic similarity might affect speed in this task, changing the slope of the function relating reaction time and the number of letters in CS. In fact, only visual similarity had an effect, increased visual similarity increasing the reaction time in the visual comparison search and memory search. Chase and Posner concluded that a visually coded representation of the stimulus was used in these situations.

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  1. 1

    Sperling, G., Human Factors, 5, 19 (1963).

  2. 2

    Conrad, R., Brit. J. Psychol., 55, 75 (1964).

  3. 3

    Nikerson, B. S., Perceptual and Motor Skills, 24, 543 (1967).

  4. 4

    Sternberg, S., in Models for the Perception of Speech and Visual Form (edit. by Wathen-Dunn, W.), 187 (MIT Press, Cambridge, 1967).

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WILCOX, L., WILDING, J. Effect of Item Similarity on the Speed of Memory Search. Nature 227, 1152–1153 (1970) doi:10.1038/2271152a0

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