2. Eye tracking empowers you to quantify visual behavior
That means you can calculate exactly when, where, and for how long someone looks at a particular area. Depending on your eye tracker, gaze location can be determined at the resolution of a singular pixel, with timing at the resolution of milliseconds. Calculating the order of fixations is also possible – for example, the participant looked first at the sheet music for 200 ms, then the piano for 160 ms, then their right hand for 400 ms. This makes your data much more precise and powerful.
Eye tracking has a variety of easy-to-use metrics, like total fixation duration or fixation count. Depending on the sampling rate, you may also be able to calculate saccade amplitude and velocity, to not only understand general attention, but also how the participants’ move their eyes as they search for information.
Additionally, visual behavior is itself a good proxy for certain cognitive and physiological concepts. By calculating changes in pupil diameter, you can understand the participant’s cognitive processing, interest, arousal, or fatigue. Finally, qualitative tools, like heat maps and gaze plots, add to the overall holistic understanding of visual behavior.