Context-us association as a determinant of long-term habituation in the crabChasmagnathus

An opaque screen moving overhead elicits an escape response in the crabChasmagnathus that habituates for a long period after just a few presentations. A series of experiments was performed to determine whether the crab’s long-term habituation (LTH) is mediated by an association between contextual cues and the eliciting stimulus.Chasmagnathus failed to exhibit LTH when a visual cue in the experimental environment was changed between training and testing. In addition, long-term exposure to the context in the absence of the eliciting stimulus impaired LTH, both when the exposure preceded the habituation training (latent inhibition) and when the exposure came after the training (extinction). Long exposure to the context alone prior to training also produced a decrease in responsiveness to the eliciting stimulus, which confirmed previous results. However, both effects of long exposure were only manifested when the crabs spent a period of time between exposure and testing out of the experimental context. The results of this paper are interpreted as supporting the view thatChasmagnathus LTH can be understood largely by Wagner’s associative theory of habituation.