Arousal and activation are two serious candidates supposed to be responsible for the changes of response force (RF). This study was undertaken to explain the role of strong auditory stimuli and sleep deficit. Loud tones can evoke phasic overarousal whereas sleep deficit leads to general underarousal. Accordingly, loudness was found to modulate RF. However, Jaskowski and Wlodarczyk (1997) found no significant effect of sleep deficit on RF. Moreover, Van der Molen and Keuss (1979) showed that paradoxically long reaction times (RT) occur with extremely loud signals when the task is difficult. They argued that this behavior of RT is due to active disconnecting of the coupling between arousal and activation. Thus, we predict for extremely loud stimuli and for difficult tasks lengthening of RT associated with reduction of RF.
The effects of loudness and sleep deficit on RT and RF were investigated in three different tasks: Simon paradigm, choice and simple response. The signals were tones (1000 and 3000 Hz) presented monaurally either to the left or to the right ear. Their sound levels ranged from 50 to 110 dB.
We found detrimental effect of sleep deficit on RT and on RF. RT decreased monotonously with stimulus intensity: we found no increase of RT for loud stimuli. RF was larger for louder stimuli, independent of tasks. There was no effect of task on RF.
These results agree with the hypothesis that RF is determined by arousal evoked by a intense stimulus (immediate arousal) or by general factors like sleep deficit.
This work was carried out with the help of a grant from Polish Committee for Scientific Research (KBN, H01F 003 15).
Poster in der Gruppe Handlung und Motorik, Mittwoch, 31. März 1999, 17:00-19:00, Foyer 2. Stock
