ABSTRACT
A major force guiding much of the contemporary work on invertebrate learning is the use of what has become known as the simple system approach. In this approach invertebrates are subjected to various nonassociative and associative conditioning paradigms in the hope that the cellular basis of the behavioral change may be revealed. Nonassociative learning is a form of behavior modification in which the presentation of a stimulus leads to an altered strength or probability of a response according to the strength and temporal spacing of that stimulus. This type of behavioral change is studied by using procedures that generate habituation and sensitization. In contrast to nonassociative learning, associative learning is generally considered more complex because the range of what can be learned is vastly expanded. For example, an association can be formed between two or more stimuli, two or more responses, or between a stimulus and a response. This type of behavioral change is studied by using procedures that generate classical, instrumental and/or operant conditionmg.
