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Many behaviors require choosing between conflicting options competing against each other in visuomotor areas. Such choices can benefit from top-down control processes engaging frontal areas in advance of conflict when it is anticipated. Yet, very little is known about how this proactive control system shapes the visuomotor competition. Here, we used electroencephalography in human subjects (male and female) to identify the visual and motor correlates of conflict expectation in a version of the Eriksen Flanker task that required left or right responses according to the direction of a central target arrow surrounded by congruent or incongruent (conflicting) flankers. Visual conflict was either highly expected (it occurred in 80% of trials; mostly incongruent blocks) or very unlikely (20% of trials; mostly congruent blocks). We evaluated selective attention in the visual cortex by recording target- and flanker-related steady-state visual-evoked potentials (SSVEPs) and probed action selection by measuring response-locked potentials (RLPs) in the motor cortex. Conflict expectation enhanced accuracy in incongruent trials, but this improvement occurred at the cost of speed in congruent trials. Intriguingly, this behavioral adjustment occurred while visuomotor activity was less finely tuned: target-related SSVEPs were smaller while flanker-related SSVEPs were higher in mostly incongruent blocks than in mostly congruent blocks, and incongruent trials were associated with larger RLPs in the ipsilateral (nonselected) motor cortex. Hence, our data suggest that conflict expectation recruits control processes that augment the tolerance for inappropriate visuomotor activations (rather than processes that downregulate their amplitude), allowing for overflow activity to occur without having it turn into the selection of an incorrect response. Motor choices made in front of discordant visual information are more accurate when conflict can be anticipated, probably due to the engagemen

Current models of decision making postulate that action selection entails a competition within motor-related areas. According to this view, during action selection, motor activity should integrate cognitive information (e.g., reward) that drives our decisions. We tested this hypothesis in humans by measuring motor-evoked potentials (MEPs) in a left finger muscle during motor preparation in a hand selection task, in which subjects performed left or right key presses according to an imperative signal. This signal was either obvious or ambiguous, but subjects were always asked to react as fast as possible. When the signal was really indistinct, any key press was regarded as correct, so subjects could respond "at random" in those trials. A score based on reaction times was provided after each correct response, and subjects were told they would receive a monetary reward proportional to their final score. Importantly, the scores were either equitable for both hands or favored implicitly left responses (reward(neutral) and reward(biased) blocks, respectively). We found that subjects selected their left hand more often in the reward(biased) than in the reward(neutral) condition, particularly after ambiguous signals. Moreover, left MEPs were larger, as soon as the signal appeared, in the reward(biased) than in the reward(neutral) conditions. During the course of motor preparation, this effect became strongest following ambiguous signals, a condition in which subjects' choices relied strongly on the reward. These results indicate that motor activity is shaped by a cognitive variable that drives our choices, possibly in the context of a competition taking place within motor-related areas.