Note on the invariance of response latency in shuttlebox avoidance learning

Rats trained to avoid shock by running in a shuttlebox showed an orderly increase over trials in the probability of avoidance but no corresponding change over trials in the latency of the avoidance response. Both responding in the presence of shock (escapes) and responding prior to shock onset (avoidances) appeared to be stationary in time. Latencies were found to vary with different experimental conditions but in every case to be invariant over trials.