Warning signals induce automatic EMG activations and proactive volitional inhibition: evidence from analysis of error distribution in simple RT.
Typical simple reaction-time (RT) paradigms usually include a warning signal followed by a variable foreperiod before the presentation of a reaction stimulus. Most current interpretations suggest that the warning stimulus alerts the organism and so results in faster processing of either the sensory or motor components of the task. In this study, electromyography (EMG) was used to detect both covert and overt motor errors in a simple warned RT task. Results show that warning signals may trigger automatic motor activations that are likely to cause false alarms. Distribution analysis reveals that 77% of all errors detected with EMG are erroneous responses to the warning signal. Accordingly, we propose that movement triggering needs to be temporarily inhibited before the stimulus to prevent premature responses during the foreperiod. This proactive inhibition would be responsible for a paradoxical increase in RT for conditions with short foreperiods compared with control conditions in which no warning signal is presented. These results call for a reassessment of the theoretical framework used to interpret the effects of warning signals.
Boulinguez
Philippe
P
Centre de Recherches sur la Cognition et l'Apprentissage, Equipe Attention and Contrôle, CNRS UMR 6234, Universite de Poitiers, 99 Avenue du Recteur Pineau, Poitiers, France. pbouling@univ-poitiers.fr
Jaffard
Magali
M
Granjon
Lionel
L
Benraiss
Abdelrhani
A
D000293:Adolescent; D000328:Adult; D001288:Attention / Q000502:physiology; D004576:Electromyography; D006801:Humans; D008297:Male; D010775:Photic Stimulation / Q000379:methods; D011334:Proactive Inhibition; D011930:Reaction Time / Q000502:physiology*; D017603:Signal Detection, Psychological / Q000502:physiology*; D013647:Task Performance and Analysis; D014836:Volition