Michele Scaltritti, investigadora principal do projeto de investigação 79/20 - Redefining the boundaries between cognition and action through the psychophysiological investigation of binary decisions, apoiado pela Fundação BIAL, publicou no Journal of Experimental Psychology: Human Perception and Performance o artigo Redefining the Decisional Components of Motor Responses: Evidence From Lexical and Object Decision Tasks. A equipa de investigação pretendia analisar se a execução da resposta motora integra ou não o processo de decisão. Recorrendo ao sinal eletromiográfico (EMG) dividiram o tempo de reação no tempo pré-motor (intervalo de tempo entre o início do estímulo e o início da atividade EMG) e no tempo motor (intervalo de tempo desde o início do pico de amplitude do EMG até ao pressionar do botão), para avaliar se o processo de decisão termina antes do início da resposta ou, pelo contrário, se ainda persiste durante a execução da resposta motora. Os resultados apoiam esta última perspetiva, isto é, a execução da resposta motora está integrada na dinâmica de decisão em curso.
ABSTRACT
Models of decision making focusing on two-alternative choices have classically described motor-response execution as a nondecisional stage that serially follows the termination of decision processes. Recent evidence, however, points toward a more continuous transition between decision and motor processes. We investigated this transition in two lexical decisions and one object decision task. By recording the electromyographic (EMG) signal associated with the muscle responsible for the manual responses (i.e., button press), we partitioned single-trial reaction times into premotor (the time elapsing from stimulus onset until the onset of the EMG burst) and motor times (the time elapsing from the onset of the EMG burst and the button press), with the latter measuring response execution. Responses were slower for pseudowords and pseudo-objects compared to words and real objects. Importantly, these effects were reliable even at the level of motor time measures. Differently, despite the reliable effect at the level of reaction times and premotor times, there was no difference in motor times between high- and low-frequency words. Although these results, in line with recent evidence, challenge a purely noncognitive characterization of motor-response execution, they further suggest that motor times may selectively capture specific decisional components, which we identify with late-occurring verification and/or control mechanisms.
