Guest Lecture of Dr. Olaf Dimigen

Guest Lecture of Dr. Olaf Dimigen

from Humboldt Universität zu Berlin & Universität Potsdam

Date: 24.11.2010

Topic: Simultaneous recordings of EEG and eye movements in natural vision: Applications, chances, and open problems

Abstract:

To avoid measurement artifacts, event-related brain potentials (ERPs) are typically recorded while subjects are instructed to maintain a steady fixation. This procedure has many advantages, but it also differs from everyday visual perception, which involves an active sampling of the environment with 2-3 saccadic eye movements per second. An alternative approach to EEG analysis, summarized in the present talk, is to align the EEG not to stimulus presentations, but to the onsets of individual eye fixations while subjects are allowed to move their eyes freely. This approach requires simultaneous high-resolution eye tracking and the handling of several technical and data-analytical problems. To exemplify that this technique is a useful addition to standard ERP methodology, I will present data from two different lines of research: In the first line of research, we have investigated how visual-cortical potentials from involuntary micro-saccades can influence ERP results even in traditional paradigms that require a steady fixation. In a second line of research, the technique was used to study the time course of word recognition during natural, left-to-right sentence reading. In particular, I will focus on the theoretically relevant question whether readers are able to extract semantic information from upcoming words in the parafovea that have not yet been directly fixated.