Eye movement studies

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Eye movement studies

In an eye tracking experiment the eye movements of a participant are measured. The points of fixations are recorded (the locations on which the gaze is focused) as well as the saccades (the movements of the eye between the phases of fixations).

The eye tracking lab

Our Lab Manager, Ms. Kilter is sitting as a participant at the eye tracker. An infrared camera records her eye movements at 1000 data points per second. On the basis of these images the software calculates the positions and the durations of the fixations and the saccades. Before the beginning of the recording, the eye tracker has to “learn” how the gaze of each individual participant relates to the stimulus presented on the screen. To do that calibration is performed, during which the participant fixates at specific points on the screen. The experiment starts when calibration is successful.

The lens of the eye tracker can be adjusted so that the images of the eye movements are accurate and free of artefacts. We typically use three different experimental paradigms in our lab. In a reading study, the eye movements are recorded while a participant reads sentences and larger texts on the screen. We are mainly interested here in the durations of the first fixations, the total reading times and the length of the saccades. As the name implies, in the Visual World Paradigm, images are presented on the screen creating small situations. At the same time, some auditory stimulus is presented. We are interested in the way this auditory information affects how the participant’s gaze is directed to the different objects on the screen. In the third paradigm, pupillometry, pupil sizes are measured as a function of the processing of the stimulus.