Hemispheric asymmetry and human classical conditioning to verbal and non-verbal visual CSs.

Abstract

AbstractA new paradigm called “the dichoplic acquisition paradigm” was developed to study Ihc effects of hemispheric asymmetry on classical etcctrodcrmal conditioning. The paradigm involves three phases: 1) A habituation phase where two different color‐words written in two incongruent colors are tachistoscopically displayed bilaterally to the visual half‐fields left and right of center fixation; 2) An acquisition phase, wherein the display is followed by a 105dB white noise on each trial; and 3) An extinction phase, where each of the four CS cues (two color‐words and two colors) are separately presented bilaterally for simultaneous input to both hemispheres. Here the color‐words are now presented in grey against a black background, and the colors as color‐bars against the same background. A control group had no UCS presentations. Bilateral skin conductance responses (SCRs) of right‐handed males were used to evaluate conditioning. Conditioning to the CS color‐word previously presented in the right half‐field (i.e. initial left‐hemisphere input) during acquisition led to larger SCRs during extinction, than the color‐word previously presented in the left half‐held (i.e. initial right‐hemisphere input). In contrast, the CS color cue previously presented in the left half‐field during acquisition resulted in larger SCRs during the first extinction trial, than the CS color cue previously presented in the right half‐field. Thus, the present experiment revealed effects of hemispheric asymmetry on human electrodermal conditioning.