Faculty Advisor

Andresen, David

Area of Study

Arts, Humanities and Social Sciences

Publication Date

Summer 2015


Relatively little is known about the role of brain oscillations in relation to cognitive function. While oscillations of all frequencies have be associated with most any neural process, no conclusive data has been found to support if oscillations are simply emergent or if they play a causal role in cognitive functions. To make headway on this problem, we employed entrainment, a technique used to synchronize brain oscillations. Entrainment was achieved by presenting subjects with alternating images of a neutral face and a scrambled face at 4 Hz such that the faces were presented at 2 Hz. After a few seconds of entrainment, a target image of either a face expressing happiness or disgust, or another scramble, was shown in-phase or out-of-phase of the entraining faces and followed by a masking image. Subjects were asked to identify if the target image was a scramble or a face, and if the face was expressing happiness or disgust. By monitoring neural activity with electroencephalography (EEG), we found that entrainment was successful. Oscillations in the occipital cortex were strongest around 4 Hz, and those in the parietal, central, and frontal cortices were strongest around 2 Hz. We also found that faces shown in-phase were easier to detect than those shown out-of-phase. Thus, initial results suggest entrainment can influence facial perception.


University of Puget Sound