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

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 groups factorial design (N = 90). On the basis of Sokolov's (1966) theory, it was hypothesized that: (a) high information stimuli would elicit larger initial SCR'S than would stimuli of low information, (B) high-information stimuli would evoke more SCRs throughout a habituation series than would low-information stimuli, and (c) high-information stimuli would require more presentations to reach a habituation criterion than would stimuli of low information. It was also hypothesized that (d) 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 hypotheses (b), (c) and (d), but not for hypothesis (a). These results support the view that OR habituation can be conceptualized as a process of information extraction.