Pseudo-conditioning without paired stimulation encountered in attempted backward conditioning.

Abstract

The present experiment was planned as ah attempt to obtain conditioning of an emotional response in monkeys when the usual sequence of stimuli was reversed (i.e., backward conditioning).Backward conditioning is extremely important from a theoretical standpoint, as is evident from the part it plays in the learning theories of Hull (6), Hunter (7), and Guthrie (4).The contradictory nature of experimental data concerning backward conditioning has been pointed out by Cason (3). Two typical conditioning experiments, one carried out by Wolfle ( 12), and another by Switzer (11), have been widely quoted as evidence for backward conditioning. In both experiments the conditioning was of a skeletal muscle response in human subjects. In such a situation conditioning can be influenced by verbal activities [see Cason (2)].By the use of animal subjects, such as monkeys, the effects of verbalization can be avoided. The data of Pavlov (8) and Yarbrough (13) on animal learning suggest that backward conditioning may be impossible in sub-human animals.

Backward conditioning: A reevaluation of the empirical evidence.

“…In summary, these experiments by Grether (1938), Spooner and Kellogg (1947), and Prokasy et al (1962), which have been cited frequently as evidence that backward conditioning does not exist, in fact provide little if any support for the view that backward conditioning is not possible.…”

“…Although, as Grether (1938) suggested, this experiment demonstrates the need for pseudoconditioning control groups, it by no means provides evidence against the possibility that backward conditioning is genuine conditioning. First, "reacting violently" is not a quantifiable measure with which to make fine distinctions between the groups.…”

“…An earlier experiment by Grether (1938) has also been referenced frequently to support the view that backward conditioning may be attributed to pseudoconditioning, Grether presented two monkeys with 10 backward pairings of a US and a CS. For one subject, the US was flashlight powder that exploded 2 feet (.6 m) in front of the monkey; for the other, the US was a snake "blowout" that uncurled to 6 inches (15.24 cm) from the monkey's nose and produced a rattling noise.…”

“…Others who reported that apparent CRs occurred early in training concluded that these were not genuine CRs because their occurrence declined with repeated pairings (e.g., Spooner & Kellogg, 1947). And some experimenters (Grether, 1938;Prokasy, Hall, & Fawcett, 1962) reported that backward groups do not differ from pseudoconditioning groups. Because the results of these studies are frequently cited to support the conclusion that backward conditioning is not a genuine phenomenon (Cautela, 1965;Gormezano & Moore, 1969;Mackintosh, 1974), it is worthwhile to carefully examine the evidence provided by some of them.…”

“…Two processes that could be confused with backward conditioning in inappropriately controlled studies have been identified. Pseudoconditioning is a change in behavior to a CS that results from prior exposure to the US (Grether, 1938). For example, an animal that has just received a painful shock may exhibit a fear response to a subsequent novel stimulus.…”