Effects of stimulus content and brain lateralization on the habituation of the electrodermal orienting reaction (OR).

Slides with either a six-letter word or a complex spatial pattern were repeatedly flashed either to the left or to the right of a center fixation point (i.e. visual half-field technique) in an electrodermal orienting paradigm. Skin conductance (SC) was recorded from both the left and right hand. Half of the subjects had the slides projected 6.0 degrees of visual angle lateral to fixation, the other half had the stimuli projected 2.5 degrees lateral to fixation. There were 15 presentations of each stimulus with a mean inter-trial interval (ITI) of 30 sec. Results showed significantly larger mean SCR-amplitudes across trials to the verbal stimuli compared to the spatial patterns when presented in the right visual half-field, and larger amplitudes to the spatial stimuli when presented in the left half-field. However, this was only true for the 6.0 degrees condition, but not for the 2.5 degrees condition. No differences were found between left and right hand recording. The present data imply a functional relationship between electrodermal orienting habituation and hemispheric asymmetry.