Maximal voluntary force strengthened by the enhancement of motor system state through barely visible priming words with reward.

The topic of unconscious influences on behaviour has long been explored as a means of understanding human performance and the neurobiological correlates of intention, motivation, and action. However, what is relatively unknown is whether subconsciously delivered priming stimuli, with or without rewards, can affect individuals' maximum level of force produced with their best effort. We demonstrated using transcranial magnetic stimulation that barely visible priming of an action concept, when combined with a reward in the form of a consciously visible positive stimulus, could alter the state of the motor system. In accordance with this neurophysiological alteration, the prime-plus-reward stimuli significantly increased the hand-grip force level of maximum voluntary contraction with little conscious awareness. This is the first objective evidence that the barely conscious presence of a behavioral goal can influence the state of the motor system and arouse latent ability for human force exertion

Effects of barely conscious goal pursuit on motor action.

<p>A: Typical recordings of hand-grip force after three experimental conditions. B, C, D: Reaction time (B), Rate of force (C), and Total effort (D) for the three conditions. Data are expressed as mean ± SEM. The asterisks in panel B indicate statistically-significant differences between the control and the priming-plus-reward conditions, and the asterisks in panels C and D indicate statistically -significant differences compared with other conditions (*<i>p</i><0.05, **<i>p</i><0.01).</p

Effects of barely conscious goal pursuit on MEP amplitude.

<p>A: Typical recordings of the average MEP of all 50 trials for FCU during three experimental conditions in a singleparticipant. Arrows indicate the timing of TMS. B: Amplitudes of MEPs for the three experimental conditions. Data are expressed as mean ± SEM. Asterisks indicate statistically -significant differences compared with other conditions (*<i>p</i><0.01).</p

Priming procedure.

<p>In the priming-plus-reward condition, the subliminal barely visible exertion primes were always paired with positive words. In the priming condition, although exertion primes and positive words were both displayed, they were never paired with each other. In the control condition, subliminal barely visible exertion words were never displayed. The order of possible stimulus pairs was randomized within each condition. Exertion, positive, and neutral words were Japanese. Each trial in each condition began with a 1000-ms presentation of a random eight-letter string (e.g., DZXLTOTM) as a forward mask. This was followed by the subliminal barely visible prime, displayed for 33 ms. A random letter string was again displayed for 100 ms as a backward mask, after which a consciously visible word was presented for 150 ms. Occasionally, a dot was presented for 33 ms (it was visible because of the absence of a backward mask), either above or below the neutral or positive word.</p

Effects of a barely conscious motivator on MVC.

<p>MVC for the three conditions. Data are expressed as a percentage of baseline values (mean ± SEM). An asterisk indicates statistically-significant differences compared with other conditions (*<i>p</i><0.01).</p