Tag Archives: eye tracking

Taking It All in: Data and Eye Movement

After the details of the electrooculargram and seeing how difficult the results could be, this articular was a bit of a relief. Berger, Winkels, Lischke, and Höppner offer a program capable of analyzing the raw data of eye tracking in “GazeAlyze: A MATLAB toolbox for the analysis of eye movement data.” It was not any less detailed or methodical than the article about raw electrooculargraphy, but knowing that there is a program like GazeAlyze that works through MATLAB, a program available on a number of universities, including Alabama, made eye movement a more feasible experimental measure. This also opens up the possibility that researchers experienced in MATLAB would find the eye tracking data easy to read, or at least could become familiar with the analysis relatively easily.

Beyond my personal relief, the authors note a few improvements that would be convenient for researchers and improve on previous software such as ILAB. GazeAlyze allows files to be exported as images and marking of regions of importance (ROI). Although these features might be easier to use if the subjects look at static images while their eye movements are tracked, they also allow easier sharing and reproduction of results. In particular, compared to the raw data of eye movements, heat maps generated by the program would be more intuitive to understand.

Berger, C., Winkels, M., Lischke, A., & Höppner, J. (2012). GazeAlyze: A MATLAB toolbox for the analysis of eye movement data. Behavior Research Methods44(2), 404-419. doi:10.3758/s13428-011-0149-x

A Look at Eye Tracking

Although it tends toward the sci-fi side of tracking eye movement, particularly in it’s discussion of “brain-to-machine interface (BMI),” the Fricke, Sobot, and Dounavis in their article “Analogue portable electrooculargram real-time processor” show that measuring eye movement is feasible on a small scale, opening the possibility of future applications.

The authors looked at a simple electrooculargram with five electrodes: one centered on the forehead, two above either eyebrow to measure vertical movement, and two on the outside of either eye to measure horizontal movement. Although it would be difficult to determine exactly where someone is looking, this instrument should give enough information for the purposes of studying where students are looking in a classroom and what sort of stimuli they respond to, such as the teacher’s gaze and emoting or material on the board. Ideally, five electrodes would not be too invasive or distracting for a period of about an hour, and the low power requirement and real time data would be helpful in the field.

I cannot speak for the technical details of the circuits and signal processing, but the authors show some favorable results. Their primary focus was on clear, precise movements involved in tracking a white dot that moves only horizontally or vertically, which do not match up with the more varied eye movement in a classroom setting, but could be adapted. They note that trained subjects produce clearer results, which is not unexpected. Nevertheless, with some signal boosting and processing, the electrooculargram gives a clear indication of eye movement with even a simple instrument.

Looking at their results, researchers would have to have significant training to interpret them, which might be a significant setback for a real proposal. Unless their instrument can be adapted to produce results that are more intuitive to interpret or can be processed by another program to produce clearer graphs and figures, then the utility of eye tracking instruments might be limited.

 

Fricke, K., Sobot, R., & Dounavis, A. (n.d). Analogue portable electrooculogram real-time signal processor. International Journal Of Circuit Theory And Applications, 42(2), 195-208.