the stimulus-model comparator theory emerged from the research of sokolov who used the orienting response as the cornerstone of his studies, and operationally defining the orienting response as eeg activity. orienting responses are heightened sensitivity experienced by an organism when exposed to a new or changing stimulus. orienting responses can result in overt, observable behaviors as well as psychophysiological responses such as eeg activity and undergo habituation with repeated presentation of the eliciting stimulus. the sokolov model assumes that when a stimulus is experienced several times, the nervous system creates a model of the expected stimulus (a stimulus model). with additional presentations of the stimulus, the experienced stimulus is compared with the stimulus model. if the experienced stimulus matches the stimulus model, responding is inhibited. at first the stimulus model is not a very good representation of the presented stimulus, and thus responding continues because of this mismatch. with additional presentations the stimulus model is improved, there is no longer a mismatch, and responding is inhibited causing habituation. however, if the stimulus is changed so that it no longer matches the stimulus model, the orienting response is no longer inhibited. sokolov locates the stimulus model in the cerebral cortex.