The development and the extinction of hyperthermia induced by conditioned avoidance behavior in rats.

Researchers taught rats to avoid a mild shock by jumping onto a shelf. Each jump also stopped a warning buzzer.

After many trials the rats jumped as soon as the buzzer sounded. The team then measured the rats’ body heat. The animals ran a fever every time the buzzer came on.

Next the scientists started extinction. They kept the buzzer but removed the shock. They wanted to see if the fever would fade once the jump was pointless.

The rats stopped jumping after a few sessions. Their fever did not budge. Nine full extinction days passed and body heat stayed high.

The takeaway: the body can keep a conditioned response long after the behavior it once served has disappeared.

Anger et al. (1976) later showed the same pattern in lever pressing. Early responses dropped but late responses rose, so daily totals never changed. Both studies warn that extinction curves can hide stubborn remnants.

Velasquez et al. (2025) added a twist: when brief timeouts returned, the old escape responses came back. If the fever is part of that chain, it could reappear too.

Bai et al. (2016) found the opposite risk. Reinforcing a new behavior while you withhold the old one can make the old response even harder to kill. Together these papers tell us extinction is rarely a clean finish.

Your client may stop hitting the table yet still feel the same surge of heart rate or temperature. If you declare victory after the behavior drops, you might miss the physiology that can drive relapse. Track simple body signs—skin color, perspiration, breathing rate—during extinction. Keep extinction sessions short and revisit the data over days. The body’s memory can outlast the behavior you see.