Motor activation with and without inhibition: Evidence for a threshold mechanism in motor control

Abstract

Masked primes presented prior to a target can trigger response activation processes that may later be subject to inhibition. Evidence for response inhibition has previously been obtained with primes presented at fixation, but not with primes presented in the periphery of the visual field. It is argued that this central-peripheral asymmetry reflects a threshold mechanism in motor control. Foveal masked primes give rise to stronger perceptual representations than do peripheral primes, resulting in stronger response activations. Strong response activations are actively inhibited, whereas weaker activations remain below a hypothetical inhibition threshold. Evidence in favor of this hypothesis is obtained in four experiments that manipulated the perceptual strengthof foveal and peripheral primes. Experiments 1 and 2 demonstrate that when the perceptual strength of peripheral primes is gradually increased by delaying mask onset, positive prime-target compatibility effects (reflecting the absence of response inhibition) turn into negative effects (indicating the presence of response inhibition). Experiments 3 and 4 demonstrate that when the perceptual strength of foveal primes is gradually decreased by degradation, negative compatibility effects turn into positive effects. The results are discussed in terms of a simple functional model of early motor control.

Inhibition and decay of motor and nonmotor priming

“…This finding suggests that the inhibition of the priming effect depends on the activation that was achieved initially by the primes because the priming effect is typically larger when PM-SOA is increased (e.g., Mattler, 2003;Vorberg et al, 2003). This finding accords with the account of Schlaghecken and Eimer (2002), who proposed a model for the reversal of priming effects. According to this model, each response alternative is controlled by an excitatory and an inhibitory unit in the motor control system.…”

Attentional modulation of sensorimotor processes in the absence of perceptual awareness

“…3) used cueing while investigating differences between primes presented at fixation and in the periphery, and they found a slightly greater positive compatibility effect for cued primes. In a different study, on the other hand, increasing the perceptual strength of peripheral primes by delaying mask onset was found to reverse the compatibility effect (37).…”

Context, not conflict, drives cognitive control.

“…Note that in the Cueing and the Simon task, response-relevant and responseirrelevant information could be readily distinguished by their location, whereas in the Priming task, this was not the case. To reduce this additional difficulty, an empty 'frame'-like stimulus was inserted between prime and target in this task in a procedure identical to the one employed by Schlaghecken and Eimer (2002). (In this example, the distractor is associated with a left-hand response, and the target requires either a left-hand (compatible) or a right-hand (incompatible) response.)…”