Question

Is latency (physiology) the time from the stimulus to the end of a response or the time from the stimulus to the start of a response?

Answer 1

Latency is the time from the stimulus to the start of a response.

Explanation:

Latency comes from latent, and the Latin verb latere meaning to lie hidden or lurk.

When an action is being performed it is no longer hidden, and so is not latent.