Spontaneous recovery

Spontaneous recovery is a phenomenon of learning and memory that was first named and described by Ivan Pavlov in his studies of classical (Pavlovian) conditioning. In that context, it refers to the re-emergence of a previously extinguished conditioned response after a delay. Such a recovery of 'lost' behaviors can be observed within a variety of domains, and the recovery of lost human memories is often of particular interest. For a mathematical model for spontaneous recovery see Further Reading. Spontaneous recovery is a phenomenon of learning and memory that was first named and described by Ivan Pavlov in his studies of classical (Pavlovian) conditioning. In that context, it refers to the re-emergence of a previously extinguished conditioned response after a delay. Such a recovery of 'lost' behaviors can be observed within a variety of domains, and the recovery of lost human memories is often of particular interest. For a mathematical model for spontaneous recovery see Further Reading. Spontaneous recovery is associated with the learning process called classical conditioning, in which an organism learns to associate a neutral stimulus with a stimulus which produces an unconditioned response, such that the previously neutral stimulus comes to produce its own response, which is usually similar to that produced by the unconditioned stimulus. Although aspects of classical conditioning had been noted by previous scholars, the first experimental analysis of the process was done by Ivan Pavlov, a nineteenth-century physiologist came across the associative effects of conditioning while conducting research on canine digestion. To study digestion, Pavlov presented various types of food to dogs and measured their salivary response. Pavlov noticed that with repeated testing, the dogs began to salivate before the food was presented, for example when they heard the footsteps of an approaching experimenter. Pavlov named this anticipatory behavior the 'conditioned' response or, more exactly, the 'conditional' response. He and his associates discovered and published the basic facts about this process, which has come to be called classical or Pavlovian conditioning. Among the phenomena that Pavlov observed was the partial recovery of a classically conditioned response after it had been extinguished by withholding the unconditioned stimulus. This recovery happened in the absence of any further unconditioned stimulation. Pavlov referred to this phenomenon as spontaneous recovery. Although spontaneous recovery increases with time following the extinction procedure, such conditioned responses do not generally return to full strength. Moreover, with repeated recovery/extinction cycles, the conditioned response tends to be less intense with each period of recovery. On the other hand, reconditioning by pairing the same conditioned and unconditioned stimuli usually occurs much faster than the original conditioning. A key conclusion is that extinction leaves a permanent trace; it does not simply reverse conditioning. This conclusion has been very important to both theories of classical conditioning and to its applications in behavioral therapy. Spontaneous recovery as it pertains to human memory can be traced back to the work of George Edward Briggs, who was concerned with the concept of retroactive interference. Inhibition, or interference, is a function of competition among responses, whereby a resultant memory has dominance over another. It is not that the inhibited responses are lost from memory per se, but that they are kept by other responses from appearing. Retroactive interference is the psychological theory of memory whereby learning something new impedes retrieval of a memory that was previously learned. Briggs studied retroactive interference using a test of free recall. In his study, participants learned paired associate words (i.e. A1-B1, A2-B2,...Ai-Bi) over multiple trials, until the learning of the Ai-Bi associates were perfected. Following this, participants were given a new list of paired associates, where the second word of the pair was changed while the first word of the associate pair was kept the same (A1-C1, A2-C2,... Ai-Ci). After mastery of this second list of paired associates, Briggs had participants perform a recall procedure. He presented a list A item and the participant was asked to recall whichever pair (the -Bi or –Ci) that came to mind. Based on retroactive interference, learning of A-B paired associates declined due to the learning of the subsequent A-C associates, and as a result, there was a higher rate of responses from list C by the participants on the recall test. One day (24 hours) after learning both sets of associates, participants were again tested. Observed was a spontaneous recovery of Bi responses such that participants' responses of Bi items exceeded Ci items. It appeared that after a rest period, participants could spontaneously remember the initial paired associates that they were not able to remember following the subsequent presentation of a second paired associate list the day prior. This A-B, A-C paradigm was replicated by researcher Bruce R. Ekstrand, thus increasing confirmation regarding the existence of spontaneous recovery. In an experiment conducted to further the findings of Briggs and Ekstrand, it was discovered that sleep counteracts retroactive interference compared to wakefulness. Using the same A-B, A-C paradigm, results indicated that memory performance for the first list of word-pair associates (A-B) was superior when learning was followed by nocturnal sleep rather than when learning was followed by wakefulness. Sleep differentially affected the memory consolidation of the two lists, enhancing more significantly, the memory for the first list. It has been suggested that it is mainly the degree of initial learning that predicts whether spontaneous recovery shall occur, stating that the better the learning of the A-B associations, the more likely they are to recover after interference. This effect is further catalyzed by sleep, which appears to having an enhancing effect on memory consolidation.