The IRF houses a laboratory which has a yoked and synchronized dual 64 channel EGI EEG system which allows for hyper-scanning of pairs of research participants during the execution of perceptual, cognitive or affective activation tasks with very high temporal resolution (to 1 ms accuracy). The EEG system is also yoked to a Tobi infra-red eye tracking system which can be used in a stand-alone mode or in conjunction with the EEG system. The EEG system can be used to study special populations including infants.
The ongoing EEG consists of a continuous varying signal composed of various frequencies that change with the subject’s state of alertness and perceptual, cognitive and affective demands. Therefore, a number of different analyses can be performed.
By synching stimulus delivery with EEG data acquisition, stimulus-locked activity (event-relatedpotentials) can be recorded. Analysis in the time domain of peak ERP amplitudes and latencies, as well as topographic voltage maps of activity across the scalp can be performed.
Particular deflections in the ERP have been linked to specific processes. For example, the negative going response 170 ms post stimulus onset has been linked to face processing. The timing of ERPs provide information regarding the timing of cognitive functioning.
Time Frequency Analysis
Time-frequency analysis allows the EEG signal to be decomposed into its component frequencies as a function of time. There are five major frequency bands (delta, theta, alpha, beta, gamma) each being linked to different processes. Examining changes in the power in particular frequency bands during cognitive tasks can provide important information.
The Tobii infra-red eye tracking system allows the monitoring of pupil dilation as well as gaze position. Information regarding eye gaze can provide invaluable information regarding cognitive functioning and has been used extensively in the study of linguistics and visual object perception and recognition. Additionally measures of pupil dilation have been linked to affective states.