PAVLOVIAN CONDITIONING

Pavlovian conditioning

Pavlovian Conditioning

Introduction

"One of these things is not like the others. One of these things is kind of the same." The lyrics to this song for the kids' discrimination game popularized by the television show Sesame Street is familiar to anyone who spends time with American children.

The object of the game is to decide which one of four objects is not like the others. The game, like many decisions, requires the ability to discriminate objects based on the level of similarity of the attributes shared by the objects. In general, one must discriminate by identifying the attributes of events that are similar and those that are different.

The topic of similarity is also of interest for researchers who study basic associative processes.

Interference between Memory Representations

One area of investigation in which the role of similarity has been extensively examined is interference between memory representations. Traditionally, interference effects have been studied in the paradigms of proactive interference and retroactive interference (for reviews, see Britt, 1935; Postman & Underwood, 1973). In proactive interference the information acquired during Phase 1 interferes with the retrieval (or acquisition) of the target information trained during Phase 2, and in retroactive interference the associations acquired during Phase 2 interfere with the retrieval of the target associations acquired during Phase 1. The concepts of proactive interference and retroactive interference were developed primarily within the early studies of verbal behaviour, especially those using paired-associate stimuli (for reviews, see Slamecka & Ceraso, 1960; Swenson, 1941) and list learning. For example, in one type of retroactive cue interference study using verbal paired-associate learning, human participants were first presented with a list of independent paired associates (e.g., words, nonsense syllables, or trigrams) including a pair of associates of the form A-B (e.g., cat-tree) and then a second list of the form C-B (e.g., horse-tree), which included a pair of associates. At test, participants were presented with the common associate (B) and were asked to recall all stimuli that were paired with it. Although participants tended to learn the pairs of items over several trials, the probability that they could recall the target stimulus (A, in this example, cat) decreased if they had also been exposed to the C-B pairings (e.g., Johnston, 1968). That is, presumably the C-B association retroactively interfered with retrieval based on the A-B association, thereby attenuating the recall of Stimulus A compared to a condition in which the C-B list was not presented.

The general requirement for the observation of interference in paired-associate learning is that a shared element must exist in the two associations (tree in the previous example). In other words, some degree of similarity must exist between the target association and the interfering association in order for interference to occur. For example, an early study by Wickens, Born, and Allen (1963), using a paired-associate task with humans, demonstrated that a decrease in the similarity between the interfering material and target material decreased proactive interference.

Specifically, Wickens et al. presented participants with trigrams formed either by consonants or numbers on ...