Date of Award


Document Type


Degree Name

Doctor of Philosophy (PhD)




The peripheral electrophysiological manifestations of levels of cognitive processing and memory performance were investigated by recording heart rate, skin conductance, skin temperature and electromyogram measures during a three phase verbal task. Subjects processed words at three cognitive levels (phonetic, low semantic, high semantic), and physiological recordings were made during cue covert processing and verbalization phases. Three colored lights were used to cue subjects to the appropriate processing level for each word. An incidental memory task was given following the processing tasks. As expected, words processed at the higher cognitive levels were recalled better. There was greater physiological reactivity associated with the phonetic tasks during the cue phase, while the semantic tasks produced more reactivity during the covert processing and verbalization phases. The high and low semantic tasks were psychophysiologically differentiated, the more semantically complex task eliciting greater arousal. An analysis of recalled versus non-recalled trials indicated greater heart rate and skin conductance increases on trials that were later recalled. A multivariate regression of physiological reactivity on memory scores showed a moderate relationship, with heart rate contributing the most variance. The results were interpreted as demonstrating a definite relationship between the level of cognitive operation and the amount of physiological reactivity. The greater activation accompanying the higher processing levels seemed to reflect the degree of cognitive effort at these levels. The reactivity accompanying the cue was interpreted to reflect arousal associated with task expectancy.