Task requirement and hemifield asymmetry in tachistoscopic partial report performance

It was hypothesized that the amount and direction of differences in tachistoscopic recognition accuracy for the right and the left visual hemifield should depend on the degree to which a partial report task requires exhaustive processing of the test stimulus. Position curves for single-item report were examined using four different tasks. In the Arrow task, Ss had to report a letter which was designated by a bar marker. In the Number task, the position of the critical letter was indicated by the digits 1–8. In the Letter task, the cue stimulus was a letter, and Ss were required to report its position in the test stimulus. In the Alphabetic task, a report on the alphabetically first letter of the test stimulus was required. The tasks were designated to encourage either selective processing (Arrow and Number tasks) or exhaustive processing (Letter and Alphabetic tasks). Right-hemifield superiority was predicted for selective processing, and left-hemifield superiority for exhaustive processing. The predictions were confirmed for the Arrow and Alphabetic tasks. A complete account of the position curves in the Number and Letter tasks required a consideration of the effects of the semantic nature of the cue stimulus and/or the spatial arrangement of cue stimulus and test stimulus. It was concluded that the processing operations underlying partial report are more complex than had been assumed previously.