Eye-tracking enables software to capture which way the user’s eyes are looking and respond accordingly. Light from infrared cameras is directed toward the participant’s pupils, causing reflections in both the pupil and the cornea. These reflections, otherwise known as pupil center corneal reflection (PCCR), can provide information about the movement and direction of the eyes. Eye position can also be used as input.
Eye-tracking can be used to capture and analyze visual attention using:
- gaze points: what the eyes are looking at. If your eye tracker collects data with a sampling rate of 60 Hz, you will end up with 60 individual gaze points per second.
- fixation: if a series of gaze points is very close – in time and/or space – this gaze cluster constitutes a fixation, denoting a period where the eyes are locked towards an object.
- heatmaps: visualizations which show the general distribution of gaze points
- areas of interest (AOI): a tool to select regions of a displayed stimulus, and to extract metrics specifically for those regions. While not strictly a metric by itself, it defines the area by which other metrics are calculated.
And provide output metrics, such as:
- time to the first fixation: the amount of time that it takes to look at a specific AOI from stimulus onset
- time spent: the amount of time spent looking at a particular AOI
- Fixation sequences: based on both spatial and temporal information – when and where a user looked. This allows a picture to be built up of what is prioritized