[HCI] About Eye-Tracking...

👀 Eye movements는 크게 두 가지(fixation, saccade) 혹은 세 가지(+smooth peusuit)로 구분된다.

 

Fixations are movements that occur when the eye momentarily stops to record visual data. Although the duration of different fixations varies, the longer the fixation, the more visual data is collected. And it can indicate quite a bit of meaningful information on the user’s attention and understanding. A shorter period of time before a user’s first fixation, for example, can indicate a high level of interest or attractiveness for that point. A fixation held for a long period of time can indicate that that aspect of the stimulus is very engaging or harder to understand.

 

Saccades refer to fast jumps performed between various fixations in an inert environment. Saccades involve eye movement from an object of interest to another, intending to collect new graphic data in the highest resolution.

 

Smooth pursuit refers to the movement when the eye looks at a moving object and follows it. The eye takes in much visual data during smooth pursuit, so it’s a relevant movement in eye tracking.

 

* Another term you are likely to encounter is “fixation sequence.” This is the order and direction in which fixations occur, including data on where the user was looking as well as when they were looking at a specific point. A fixation sequence can help you understand what aspects of a stimulus the user prioritizes. One theme you may notice is that the user focuses on the center of an image at first — a phenomenon called central fixation bias.

 

 

📊 Eye tracking data is on what your users are looking at!

• Direction of gaze
• Number of fixations
• Time to the first fixation
• Blink rate
• Blink duration
• Pupil diameter

(출처: gazepoint)

 

 

📄 Gazepoint Citations Publications

https://www.gazept.com/meet-the-team/publications/?v=4326ce96e26c

Publications & Citations | Gazepoint

 

Pacheco-González, D., Argudo-Vasconez, A., Ortega-Chasi, P., Cobos-Cali, M., & Alvarado-Cando, O. (2023). Fixation Analysis of Affective Picture Processing in Aggressive Adolescent. Physical Ergonomics and Human Factors.를 통해 GP3를 이용한 eye tracking 사용 research의 methodology를 살펴볼 수 있었는데,

해당 연구는 특히 calibration image(fixation cross image)를 사용한 것이 특징이다.

 

Between each of the slides was an image called “Fixation Cross”, this image serves to focus the gaze after each visual stimulus. The sample time for each slide was 3 seconds and 2 seconds for the fixation cross.

 

 

 

📖 How to Conduct Eyetracking Studies(2009) (Bible같은 책)

https://media.nngroup.com/media/reports/free/How_to_Conduct_Eyetracking_Studies.pdf

→ Fixations vs. Time

It is possible to use heatmaps to visualize different kinds of data from an eyetracking study. Most prominently, one can color-code based on the amount of time users spent looking at things or the number of fixations users employed looking at things. In practice, there is rarely much difference between plotting fixation count or gaze duration. In either case, the red areas are the ones that are looked at the most and there are only minor differences in the coloring. We have chosen to plot all our heatmaps based on the amount of time spent looking, because that’s what most people find easiest to interpret.