Magnocellular and parvocellular influences on reflexive attention Public Deposited

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  • March 21, 2019
  • Ries, Anthony J.
    • Affiliation: College of Arts and Sciences, Department of Psychology and Neuroscience
  • There is currently disagreement in the visual attention literature regarding the stimulus features capable of triggering a reflexive shift of attention. One theory posits that features activating the magnocellular (M) visual stream, such as abruptly appearing objects with luminance contrast and low spatial frequencies, are responsible for activating the reflexive attention system (e.g. Steinman et al., 1997; Yantis and Egeth, 1997). However, recent experiments suggest stimuli activating the parvocellular (P) stream, such as isoluminant colors with high spatial frequencies, may be equally important for initiating reflexive shifts of attention (e.g. Lu, 2006; Yeshurun, 2004). Using behavioral and eventrelated potential (ERP) measures, we designed stimuli to stimulate either the M or P system to test whether the predominate activation of these systems trigger similar reflexive attention mechanisms, or if mechanisms of attentional capture are engaged differently depending on M or P activation. We predicted that similar attention effects would be observed if both pathways triggered automatic attentional orienting. However, if only magnocellular activation engages the reflexive attention system then we hypothesized that attention effects would only be seen when stimuli activated this system and not the P system. The present findings support the view that both systems are capable of triggering reflexive visual orienting. Specifically, reaction times (RTs) to target stimuli were speeded and the P1 and P300 components enhanced when spatially preceded by both M and P cues at short interstimulus intervals (ISI's), but these findings were characteristically different at long ISIs where inhibition of return (IOR) typically occurs. Further evidence supporting attention capture from M and P activation was evidenced by a greater negativity to uncued compared to cued trials at short ISIs, i.e. the IIN component. However, we also found evidence that M and P stimulation produced different effects depending on whether the target stimulus activated the M or P system. Together these results are consistent with the basic processing characteristics of the M and P pathways and show that activation either pathway can trigger a reflexive shift of visual attention.
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  • Hopfinger, Joseph
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  • University of North Carolina at Chapel Hill
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