Automatic Versus Contingent Mechanisms of Sensory-Driven Neural Biasing and Reflexive Attention

Abstract

Recent studies have generated debate regarding whether reflexive attention mechanisms are triggered in a purely automatic stimulus-driven manner. Behavioral studies have found that a nonpredictive "cue" stimulus will speed manual responses to subsequent targets at the same location, but only if that cue is congruent with actively maintained top-down settings for target detection. When a cue is incongruent with top-down settings, response times are unaffected, and this has been taken as evidence that reflexive attention mechanisms were never engaged in those conditions. However, manual response times may mask effects on earlier stages of processing. Here, we used event-related potentials to investigate the interaction of bottom-up sensory-driven mechanisms and top-down control settings at multiple stages of processing in the brain. Our results dissociate sensory-driven mechanisms that automatically bias early stages of visual processing from later mechanisms that are contingent on top-down control. An early enhancement of target processing in the extrastriate visual cortex (i.e., the P1 component) was triggered by the appearance of a unique bright cue, regardless of top-down settings. The enhancement of visual processing was prolonged, however, when the cue was congruent with top-down settings. Later processing in posterior temporal-parietal regions (i.e., the ipsilateral invalid negativity) was triggered automatically when the cue consisted of the abrupt appearance of a single new object. However, in cases where more than a single object appeared during the cue display, this stage of processing was contingent on top-down control. These findings provide evidence that visual information processing is biased at multiple levels in the brain, and the results distinguish automatically triggered sensory-driven mechanisms from those that are contingent on top-down control settings.

Different Effects of Voluntary and Involuntary Attention on EEG Activity in the Gamma Band

“…Both components showed maximal response for sites located contralateral to the target side (hemisphere by target side significant interaction: F (1,15) ϭ 8.16, p Ͻ 0.05 for P1 and F (1,15) ϭ 8.67, p Ͻ 0.05 for N170). Consistent with previous reports in the literature (Mangun and Hillyard, 1991;Hopfinger and Ries, 2005), for both attention conditions, the P1 component was larger for valid conditions compared with invalid conditions when the target was presented in the contralateralvisualfield(supplementalmaterial,availableatwww. jneurosci.org).…”

“…Similar to previous studies (Mangun and Hillyard, 1991;Hopfinger and Ries, 2005), we found evidence for early sensory processing for validly cued compared with invalidly cued locations (indicated by a larger P1 component on valid trials). However, this difference was largely unaffected by cue predictability (Doallo et al, 2005).…”

“…The most consistent finding is an increase in early sensory potentials (P1 component) elicited by a cued target compared with an uncued target (Mangun and Hillyard, 1991;Hopfinger and Ries, 2005). Later components may also be modulated, but the results are less consistent.…”

“…Later components may also be modulated, but the results are less consistent. Whereas some authors reported greater N1 on valid trials (Luck et al, 1994), others found the reverse (greater N1 on invalid trials) (Hopfinger and Ries, 2005). Hopfinger and West (2006) measured interactions between voluntary and involuntary attention manipulating the two types of attention concurrently.…”

ERPs reveal similar effects of social gaze orienting and voluntary attention, and distinguish each from reflexive attention

“…The ADJAR filter was applied to the individual participant averages before participants' data were averaged together, as in previous studies (Hopfinger & Mangun, 1998Hopfinger & Ries, 2005;Hopfinger & West, 2006;McDonald & Ward 2000). Ten iterations of the ADJAR procedure were performed, and waveforms typically stabilized after 3-6 iterations, suggesting that the procedure was robust and effective.…”