Startle reveals decreased response preparatory activation during a stop-signal task

In this study a startling acoustic stimulus (SAS) was used to probe preparatory activation during a stop-signal task. Results indicated that although the response was prepared in advance during a stop-signal task, reaction time (RT) was delayed for both control and SAS trials compared with a simple RT task. The increased RT typically observed in a stop-signal task is therefore attributed to a reduced level of preparatory activation associated with the possibility of having to inhibit the response.