The effect of perception without awareness on somatosensory reaction time using a backward masking paradigm
Taiikugaku kenkyu (Japan Journal of Physical Education Health and Sport Sciences)
This s血 dy 曲 ed the e働 ct of perception 輌 thout awareness on somatosenso 琢 simple reac − tion time using a backWard masking paradigm in nine subjects ranging 血 age from 21 to 38 years. In the backward masking paradigm , two types of electrical stimuli differing in intensity ( one type rang − ing from 1, 2to L5 times the sensory threshold of each subject , and the other ranging from 4 to 5 times the threshold )were successively delivered with a 40 − ms interstimUlus interval to the subjects '
... o the subjects ' right med1an nerve at the wrist through disk electrodes . There were three stimulation conditions :weak stimUlus alone , strong stimUlus alone , and double stimUlation ( which was the backward − masldng con − dition , with a weak stimullls always preceding a strong one ) . The subjects were asked to respond to either the weak or the strong stimu 玉 us as 叩 ickly as possible by clicking on the computer mouse but − ton, without any knowledge that the double stimUlation would be included in the experimental trials . The resUltS showed that the mean reaction time for deuble stirnIllation was signi 且cantly shorter than that for the strong stimulus condition , and that the reaction tirne for the weak stimulus was the lon ・ gest among the three conditions . The latter result dicated that the weak stimu 且 us could not be per − ceived quickly . An subjects reported that they did not perceive the weak , preceding stimulus used for double stimulation − suggesting that the weak stimulus was masked by the fonowing strong stimuLus . Therefore , the weak stimulus , without the subject being aware of it , may have facilitated the prepara − tory processes for pe oming response actions , resulting in the shorter reaction times observed with double stimulation . These fi 皿dings are discussed in terms of severa1 conceptual and empirical models of information processing for sensation , perception, and preparation of rnotor responses in simple reaction time under backward masking . Key words : somatosensory , 8imple rea ¢ tion t e , backward maski 皿9 , paraIlel ilrforma ・ tion 暉 pr es8ing ( Japan J. Phys.