Effects of stimulus information and stimulus duration on amplitude and habituation of the electrodermal orienting response

Abstract

This study was designed to investigate the effects of stimulus information and stimulus duration on the skin conductance response (SCR) component of the orienting response (OR). Three levels of stimulus information were combined with two levels of stimulus duration in a 3 x 2 independent group fractional design (N = 90). On the basis of Sokolov's (1966) theory, it was hypothesized that: high information stimuli would elicit larger initial SCRs than would stimuli of low information; high information stimuli would evoke more SCRs throughout a habituation series than would low information stimuli, and high information stimuli would require more representations to reach a habituation criterion than would stimuli of low information. It was also hypothesized that long duration stimuli would require fewer presentations to reach a habituation criterion and result in a faster rate of habituation than would stimuli of short duration. The stimuli consisted of black and white chequered patterns containing 12, 26 or 60 bits of information. Stimulus duration was either 0.5 or 4.5 sec and each subject received 20 presentations at randomly ordered intervals of 20, 25, 30 and 35 sec. The results provided support for the last 3 hypotheses, but not for the first. These results support the view that OR habituation can be conceptualized as a process of information extraction.