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Lee P. Lovejoy, Leanne Chukoskie, Richard J. Krauzlis; Attention capture alters motion discrimination. Journal of Vision 2005;5(8):505. doi: 10.1167/5.8.505.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: The effects of competition between exogenous and endogenous allocation of attention on motion discrimination are not well known. We examined how the capture of attention by abrupt onsets can improve or degrade performance in a motion-pulse variant of the coherent motion discrimination task.
Methods: The authors (N=3) performed a 2AFC motion discrimination task during fixation. Subjects were cued to the location (75% valid) of an upcoming motion pulse (160 ms duration) by the onset of an incoherent motion patch (6° diameter) that appeared 4° above or below fixation. On ‘no capture’ trials (25% of total), the cued patch appeared alone and switched briefly (160 ms) to coherent motion at a random time during the trial. On ‘capture’ trials (50%), the motion pulse in the cued patch appeared cotemporaneously with a second incoherent motion patch in the opposite field. On ‘capture+motion’ trials (25%), the pulse of coherent motion was presented in the second patch rather than in the cued patch. The motion coherence was any of 8 values. Subjects reported the perceived direction of motion with a button press. We computed coherence thresholds for each condition.
Results: We found large coherence threshold differences between the three conditions. The threshold for ‘capture’ trials was on average 56% higher than the threshold for ‘no capture’ trials, and the threshold for ‘capture+motion’ trials was 202% lower than the threshold for ‘no capture’ trials.
Conclusions: Attention capture by the second patch overrode the endogenous allocation of attention to the first patch and enhanced discrimination performance. Our task design highlights the competition between endogenous and exogenous control of attention and suggests an approach for physiological investigations of the neural mechanisms underlying both types of attentional control.
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