Conditioned stimulus as a determinant of the form of the Pavlovian conditioned response

Investigated the role of the CS as a determinant of the form of the Pavlovian CR in 5 experiments; Ss were 71 male Sprague-Dawley rats. Both stabilimeter measures of general activity and detailed observations of the behavior of the Ss in the presence of CSs anticipatory to a food UCS were obtained. In Exp I, substantially different behaviors to light and tone CSs were observed, and these differences were dependent on specific learning experience rather than on the mere presence of different stimulation at the time of response evocation. Exps II and III investigated the possibility that there was considerable communality of learning to light and tone CSs despite their evoking different CRs. In Exp II, prior conditioning of either the tone or light CS blocked the acquisition of various behaviors even though the pretrained stimulus did not itself evoke those behaviors. In Exp III, the nature of 2nd-order conditioned responding was found to be similar regardless of which 1st-order CS was used as the reinforcer. Additionally, the reinforcing powers of the light and tone CSs were found to summate. Exps IV and V showed that stimulus modality and the localizability and vertical location of visual stimuli influenced conditioned responding. Results suggest that in this conditioning situation, similar learning of a CS-UCS relation may be displayed in different overt CRs, depending on the nature of the CS. (45 ref) (PsycINFO Database Record (c) 2006 APA, all rights reserved).