Date of Award
Doctor of Philosophy
Stephen L. Crites
The effect of stimulus type on task-irrelevant evaluative categorization was examined in two separate studies by using the P3 component from event-related brain potentials. The first study presented idiosyncratic stimuli consisting of individuals that were rated by participants as either positive or negative within sequences of pictorial and verbal stimuli. The second study presented sequences of novel and familiar stimuli consisting of previously normed unattractive and neutral individuals. It was hypothesized that pictures would elicit task-irrelevant evaluative categorization processes and so would novel stimuli (relative to words and familiar stimuli, respectively). Task-irrelevance was examined by assessing P3 peak amplitude to stimuli that varied simultaneously along a task-relevant gender and a task-irrelevant evaluative dimension while participants explicitly categorized the stimuli only along the gender dimension. An odd-ball paradigm was used in which a rare stimulus (e.g., negative male) appeared in a sequence of frequent stimuli (e.g., positive males). The P3 results from study 1 showed task-irrelevant evaluative categorization processes that were similar during the presentation of both pictorial and verbal stimuli. The P3 results from study 2 also showed task-irrelevant evaluative categorization processes that were also similar during the presentation of both novel and familiar stimuli. The findings taken together suggest that pictures and novel stimuli are not more efficient than words and familiar stimuli in eliciting task-irrelevant evaluative categorical processing.
Received from ProQuest
Corral, Guadalupe, "Does type of stimulus influence task-irrelevant evaluative categorization processes?" (2009). Open Access Theses & Dissertations. 232.