Extinction normally overcomes the association between a benign conditioned stimulus (like a sound or light) and a threatening unconditioned stimulus (like an electric shock) by overlaying a newly learned memory that couples the conditioned stimulus with the absence of threat.
However, that effect often wears off over time, so the researchers used both rats and humans to test another way to extinguish fear. Rather than simply leaving out the shock, they replaced it with a new, nonaversive tone. The goal was to eliminate any ambiguity about the safety or danger of the conditioned stimulus by using the element of surprise to generate “a mismatch between the predicted and received outcome, therefore signaling a clear change in the environment to promote the acquisition of new learning” and “providing a more substantive alternative association for the conditioned stimulus than no shock,” they wrote.
If used in exposure treatments for disorders like anxiety or PTSD, this “novelty-facilitated extinction” may neutralize negative beliefs “by experiencing an unexpectedly mundane event, rather than simply experiencing the absence of a negative event.”
For more in Psychiatric News about fear extinction research, see “Context Is Critical in PTSD Fear Learning.”