Attentional spread in the statistical processing of visual displays
DOI: 10.3758/bf03195009
URL: https://doi.org/10.3758/bf03195009
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Summary
Four lab experiments testing whether distributed attention enables automatic extraction of statistical (mean-size) properties from arrays of similar items. Experiments 1-2 used a dual-task paradigm: participants judged the mean size of circles concurrently with either focused (visual search for an O among Cs) or distributed/global (search for C among Os; orientation judgment on a global framing rectangle) attention tasks. Experiments 3-4 compared simultaneous vs. successive presentation of set elements with total exposure time matched. Stimuli were arrays of outline circles presented on a Macintosh G3 via Psychophysics Toolbox; thresholds for mean-size discrimination were estimated with adaptive staircases.
Key finding
Mean-size extraction was easier under distributed/global attention than under focused/local attention, and dual-task accuracy on mean judgments did not decline relative to single-task baseline when the concurrent task itself required distributed attention — consistent with statistical processing being automatic when attention is spread. Simultaneous presentation showed only a small advantage over successive presentation, indicating parallel access facilitates but is not essential for statistical processing.
Methodology
Experimental dual-task psychophysics. Four experiments at Princeton. Exp 1: 12 participants, mean-size threshold during visual-search task (focused vs. distributed attention). Exp 2: 10 participants, mean-size threshold during local vs. global rectangle-orientation judgment. Exp 3: 10 participants, simultaneous vs. successive set presentation. Exp 4: 10 participants, replication/extension of presentation-mode comparison. Adaptive staircase thresholds; Psychophysics Toolbox on Macintosh G3.
Sample size: Exp 1: N=12; Exp 2: N=10; Exp 3: N=10; Exp 4: N=10
Quality score: 5 / 5