Spontaneous recovery

Spontaneous recovery is a term that is commonly associated with learning and conditioning. It is commonly referred to as, "one of the basis phenomena of Pavlovian conditioning; however spontaneous recovery can also be seen in a variety of other designs (Domjan 2010). It is typically noted in relation to extinction. It has been widely accepted by many scholars that extinction does not erase what has previously been learned, CR, but produces a decline in conditioned behavior, CR (Domjan 2010). Spontaneous recovery is just one of many procedures that help scholars confirm the belief that extinction is not a device that can erase a conditioned behavior, CR, from an organism. Spontaneous recovery typically occurs during a rest period between extinction training sessions. It is defined as increased recovery of a conditioned behavior, CR, that occurs during a rest period with no visible reason for it's occurrence; which is why it is labeled spontaneous.

A classic experiment that demonstrates spontaneous recovery was conducted by Rescorla. Original acquisition was conducted with two different stimuli (sucrose and a solid food pellet) which was delivered by cups recessed in one of the walls of the experimental chamber (Rescorla 1997). Rescorla used infrared detectors, is a photodetector that reacts to infrared (IR) radiation. The two main types of detectors are thermal and photonic, that identified each time the rat poked it's head into the food cups (Rescorla 1997). One of the unconditioned stimuli was signaled by a noise CS and the other unconditioned stimuli was signaled by a light CS. As conditioning progressed each CS was quickly came to elicit the goal, the conditioned response, with the two CS's eliciting the same level of responding.

Two extinction sessions comprising 16 trails each were then conducted. Each session was followed by a series of 4 test trails. The experimental manipulation of primary interest was the interval between the end of the extinction training and the test trails (Rescorla 1997). For one of the conditioned stimuli (S1) there was an eight day period separating the extinction training and the test trails. For the second conditioned (S2) the test trails were started immediately after the extinction training.

What Rescorla et al. experiment showed was that during the course of extinction training responding declined similarly in both S1 and S2 conditions. However, responding remained suppressed during the test trials conducted immediately after the extinction training whereas responding substantially recovered in the S1 condition where there was a rest period of eight days.

Spontaneous recovery may help explain why it is so hard to overcome drug addictions. For example, cocaine addicts who are thought to be "cured" can experience an irresistible impulse to use the drug again if they are subsequently confronted by a stimulus with strong connections to the drug, such as a white powder (O'Brien et al., 1992; Drummond et al., 1995; DiCano & Everitt, 2002).