It’s amazing to consider that a given thought can be generated and acted on in less than 150 ms. Consider the sprinter at a starting line. The reception and perception of the crack of the starter’s gun, the decision to begin running, issuing of the movement commands, and generating muscle force to start running involves a network that begins in the inner ear and travels through numerous structures of the nervous system before reaching the muscles of the legs. All that can happen in literally half the time of a blink of an eye.

Although the time to initiate a sprint start is extremely short, a variety of factors can influence it. One is the loudness of the auditory “go” signal. Although reaction time tends to decrease as the loudness of the “go” increases, there appears to be a critical point in the range of 120-124 decibels where an additional decrease of approximately 18 ms can occur. That’s because sounds this loud can generate the “startle” response and trigger a pre-planned sprinting response.

Researchers think this triggered response emerges through activation of neural centers in the brain stem. These startle-elicited responses may be quicker because they involve a relatively shorter and less complex neural system – one that does not necessarily require the signal to travel all the way up to the more complex structures of the cerebral cortex.