Investigating the Effect of Startle on Cognitive Performance Using a N-back Task and Prepulse

Abstract

The startle reflex is a whole-body response to a startling stimulus. The effects of a startle reflex elicited by a startling acoustic stimulus (SAS) on task performance have been reliably observed in motor tasks, with decrements in motor performance being attributed to the startle reflex. The presentation of a non-startling acoustic stimulus (prepulse), prior to a SAS has been shown to reliably decrease the amplitude of the startle reflex. This modulation, termed prepulse inhibition, has been used to diminish the startle reflex in motor performance tasks, resulting in a decrease in the decremental effects caused by startle. This phenomenon has been less examined in cognitive tasks. As such, the purpose of this experiment was to determine the effect of startle on cognitive performance, and examine whether a prepulse would reduce any decrements due to the startle reflex. In this experiment, participants performed twelve blocks of a five-minute continuous 2-back task. Throughout each block, a non-startling control stimulus (80dB), a SAS (120dB), and prepulse+SAS (80dB tone 100 ms prior to 120dB) was presented. Response accuracy (correct 2-back target acceptances and rejections) and response time was measured. The results revealed that cognitive performance was negatively affected by all stimulus types. Cognitive performance following a SAS was only mildly impacted, with participants able to maintain similar levels of accuracy to control at the cost of a slight increase in response time. Contrary to expectations, prepulse had no effect on reducing these detriments, but instead seemingly intensified them. These results suggest that any acoustic stimulus negatively impacts cognitive performance. Additionally, prepulse seems to cause more detriments perhaps due to the nature of it being two distinct acoustic stimuli, compared to one acoustic stimulus in control or SAS conditions. However, the addition of a prepulse reduced the frequency of a startle reflex, thus reducing the incidence of negative impacts on performance.