Arousing auditory stimulus modulates performance during a discriminative reaction time task

The aim of the present study was to investigate the effect of an arousing auditory stimulus without emotional connotation (brief bursts of white noise presented at a volume of 90 decibel) on normal subject performance, during a discriminative reaction time (RT) task. Two groups of subjects, with different arousal states, were recruited. The first group included subjects familiar with the experimental setting, while the second group included students participating to the experiment for a credit reward for a university course. The subjects of the latter group had a higher anxiety level as evaluated with a dedicated questionnaire. The task was a continuative quasi-random visual presentation of digits. Subjects had to press response buttons for target digits which were presented after a warning digit. During half the blocks of the task, the arousing auditory stimulus was presented to the subjects through headphones concurrently to the presentation of the warning digit. The first group of subjects showed a significant steep reduction of RTs during the presentation of the arousing stimulus, consistently with an increased arousal level, that was maintained over time. On the contrary, the second group showed slower RTs during the presentation of the arousing stimulus, due to the achievement of a non-optimal arousal level (too high). These results showed that it is possible to modulate the arousal, during a RT task, using an auditory stimulus without emotional connotation. The different performance of the subjects, related to the arousal state, also support the inverted U-shaped curve between arousal and performance.