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Keywords:

  • Electrodermal responses;
  • Classical conditioning;
  • Hemispheric asymmetry;
  • Dichotic listening

ABSTRACT

It was hypothesized that classically conditioned responses to an auditory verbal CS initially presented only to the left cerebral hemisphere would be greater than when the same CS was presented to the right hemisphere. The experiment consisted of three different phases in a dichotic extinction paradigm. During the habituation phase the CS+ and CS− were presented binaurally, and separated. All subjects were treated alike. During the acquisition phase the conditioning subjects had the CS+ but not the CS− followed by the UCS. The CS+ and CS− were presented binaurally and separated. The control subjects received no UCS presentations. During the dichotic extinction phase, half of the conditioned subjects had the CS+ presented in the right ear (i.e., with initial left hemisphere input), with the CS− simultaneously presented in the left ear (i.e., with initial right hemisphere input). The other half had the earphones reversed. The control group was similar to the two conditioning groups. During the acquisition phase, significantly larger electrodermal responses were observed to the CS+ compared to the CS− in the conditioning groups, but not in the control group. During the dichotic extinction phase, significantly more resistance to extinction was observed in the CS+ Right-Ear group compared to the CS+ Left-Ear group, with the control group revealing virtually no responding at all. It was concluded that the present results have demonstrated effects of cerebral asymmetry on rate of extinction of the classically conditioned response.