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Elisabeth M. Fine, Adam Reeves; Processing benefits from diffuse attention when the stimuli are harder to discriminate. Journal of Vision 2002;2(7):10. doi: 10.1167/2.7.10.
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© ARVO (1962-2015); The Authors (2016-present)
We (Fine, 2000, Fine & Reeves, 2001; ARVO) presented data showing that under some conditions observers are better able to identify stimuli when they are required to monitor four locations in visual space than when they are required to monitor only two. This phenomenon occurred with a letter identification task (26-alternative), but not an E-orientation discrimination task (2-alternative). Here we present data comparing multiple vs. simple discrimination tasks for the same stimuli and stimulus presentation on vs. off the primary (horizontal/vertical) meridia. Stimuli were presented at 5 deg eccentricity. In Experiment 1, 10 observers both identified 10 letters and made 2AFC discriminations on the same letters (consonant or vowel). There was no difference in performance (corrected for guessing) for either response type between the monitor-2 and monitor-4 conditions (77±2% vs. 74±4% for letter identification; 67±3% vs. 70±3% for consonant/vowel discrimination). In Experiment 2, we used the 26 letter identification task. One group of observers (n = 9) identified the letters when they were presented on the horizontal and vertical meridia, a second group when they were presented 45 deg from the primary meridia. For both presentations, performance was better in monitor-4, although the effect was reduced off the primary meridia (62±4% vs. 73±2% on meridia and 84±1 vs. 89±1% off meridia). On the meridia there was little difference in performance for the horizontal and a large difference in performance for the vertical meridian; off the meridia the benefit of monitor-4 over 2 was fairly constant across location. Inferior performance in the monitor-2 condition is surprising, as it suggests less efficient processing when attention is focused. We hypothesize that focusing attention consumes resources. Thus, while an easy task (which needs few resources) can benefit from focused attention, this benefit is overwhelmed in an effortful task, which competes for the same resources.
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