Unconscious inhibition separates two forms of cognitive control

Abstract

In the human brain, cognitive-control processes are generally considered distinct from the unconscious mechanisms elicited by subliminal priming. Here, we show that cognitive control engaged in situations of response conflict interacts with the negative (inhibitory) phase of subliminal priming. Thus, cognitive control may surprisingly share common processes with nonconscious brain mechanisms. In contrast, our findings reveal that subliminal inhibition does not, however, interact with control adaptation-the supposed modulation of current control settings by previous experience of conflict. Therefore, although influential models have grouped immediate cognitive control and control adaptation together as products of the same conflict detection and control network, their relationship to subliminal inhibition separates them. Overall, these results suggest that the important distinction lies not between cognitive or top-down processes on the one hand and nonconscious priming mechanisms on the other hand but between responsive (poststimulus) mechanisms that deal with sensorimotor activation after it has occurred and preparatory (prestimulus) mechanisms that are modulated before stimulus arrival.automatic | executive | negative compatibility | voluntary | flanker task A hallmark of cognitive control is the ability, under conditions of conflict and uncertainty, to select a required response among competing alternatives. Such control has been extensively investigated with tasks that contain situations of potential response conflict, such as the influential Eriksen flanker task (1). In this task, a target stimulus is flanked by stimuli that are either associated with the same response (congruent) or with another response (incongruent). Responses are normally slower with incongruent flankers because of coactivation of conflicting responses to flankers and target. Such conflict is assumed to be minimized by a control process that is sensitive to task demands and attempts to ensure that the correct response is made (1, 2). Moreover, this control process is thought to be adaptive so that, after a conflict situation, the system is better prepared for the next instance of conflict (3)(4)(5)(6)(7)(8).A paradigmatic example of unconscious mechanisms, however, is subliminal priming (9). In this case, stimuli are masked so that they are not consciously perceived, but such masked primes nevertheless affect subsequent responses. Investigations have also revealed an important oscillation in the priming effect (10). Initially, the prime unconsciously activates the response associated with it so that responses are sped up for subsequent targets that require the same (compatible) response and slowed down if prime and target are associated with different (incompatible) responses. This is referred to as a positive compatibility effect (PCE). However, if the delay between prime and target is extended, the priming effect reverses, producing a negative compatibility effect (NCE): primes now facilitate incompatible responses and slow down compa...

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Long trial durations normalise the interference effect and sequential updating during healthy aging

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