Principle and application of eye tracker in psychological laboratory

With the development of computer technology, many psychologists have begun to study the law of human psychological activity by eye movement. The application of eye tracking method is inseparable from eye tracker. The eye tracker can be used to obtain the real-time data of the subject during viewing the visual information, in order to explore the cognitive characteristics of the subject's visual processing information selection mode.

1 The historical beginning and early development of eye movement research

In the early Middle Ages, physiological psychology appeared as a special experimental science. Many visual experimental methods and experimental instruments are also rapidly used in psychological research. Such as: "speed display" presentation, color wheel and visual back image experiment. The most representative work of this period is lbnal Haytham's book "Kitabal Manazir", which is the first manual of physiological optics. At the beginning of the history of eye movement research, humans began to realize the role of eye movement. Due to the influence of philosophical thoughts at that time, some studies still had the idealism tendency. The research results have many speculative components, and the objectivity and scientificity are limited. These limitations reached the nineteenth century and were soon resolved by new methods.

2 Three basic ways of eye movement

The three basic ways of eye movement are gaze, saccade and follow-up movement. (1) Gaze: refers to the time that the central fossa of the eye is aimed at an object for more than 100 milliseconds. During this period, the object being gazed is imaged on the central fossa to obtain a relatively sufficient processing to form a clear image. ⑵ Eye saccade: It is a sudden change of the gaze point or gaze direction. During this process, space-time information can be obtained, but it is almost impossible to form a clearer image. ⑶Following movement: When there is relative movement between the observed object and the eyes, in order to ensure that the eyes are always watching the object, the eyeball will follow the object to move. The above three eye movements are often intertwined. The purpose is to select information and place the stimulus to be placed in the image and the central fossa area to form a clear image.

3 Basic principles of eye tracker application

At present, most of the research on eye movement technology comes from abroad. Stief2elhagen and others divided eye movement research technology into two types based on hardware and software. We know that the fixation point of the human eye is determined by the head and eye orientation. Therefore, the basic principle of hardware-based gaze tracking technology is to use image processing technology, use an eye camera that can lock the eye, and continuously record the gaze changes by ingesting infrared rays reflected from the cornea and pupil of the human eye, so as to record and analyze the gaze The purpose of the tracking process. The hardware-based method requires the user to wear a special helmet or use a head fixing bracket, which is very disturbing to the user. The software-based gaze tracking technology is to use the camera to obtain the human eye or face image, and then use the software to locate and track the human face and eye in the image, thereby estimating the user's gaze position on the screen.

4 Application areas of eye trackers

4. 1 Reading psychology

Reading speed and reading quality have always been one of the learning issues that students pay more attention to. How to improve reading speed and quality has become the main research direction of psychologists today. Compared with other methods, measuring eye kinetic energy directly reflects and reveals the internal process. It is still an ideal eye movement theoretical model to explain the relationship between eye movement and reading, but as a natural, less disturbing measurable Activity and the rapid development of eye movement technology allow us to make full use of it to measure the eye movement trajectory of the research object and understand some external laws or patterns of the individual in the reading process. During the reading process, the eye tracker can record the real-time data of the eyeball, reflecting the reader's real reading process. Through the number of fixations, the rate of fixation videos, the duration of fixation points, the distance of saccades and the number of fixations, the reader's reading effect and the crux of the problem in reading can be judged to achieve effective feedback.

4. 2 Advertising Psychology

One of the most interesting content for ad producers is to know Gu

How do customers watch advertisements, and eye trackers just meet this need. The eye tracker can record the eye movement trajectory of customers when they look at the advertisement. By analyzing the data recorded by the eye tracker, it is possible to clearly understand the order in which the customer looks at the advertisement screen, the time to fix any part of the advertisement, the number of fixations, saccades, changes in pupil diameter, etc. When a customer looks at an advertisement, the gaze time for a certain part is long, the number of fixations is large, and the pupil diameter increases. Looking at the advertisement, have you missed important information such as the manufacturer and product name in the advertisement? Whether the image of the advertisement and the overall design are appropriate is directly related to its impression among consumers and the degree of attention. An advertisement includes four parts: title, pattern (image), body (copy), and background. How can consumers be paid attention to the product instead of the background at the first time? This requires the designer to pay enough attention to whether we can achieve the desired effect. The eye tracker analyzes the data provided by us to determine the feasibility of the program.

4. 3 Sports psychology

In the course of various sports, the extraction of visual information is its basic psychological support, and the different modes of visual information extraction may reflect the differences in the level of athletes. The current eye movement research has been developed to study dynamic images or on-site simulations in sports, coupled with the application of portable eye trackers, making eye movement research possible in actual sports scenes, the experimental situation and the real situation are closer, The ecological validity of eye movement research has been improved, and the experimental results have more practical significance. Existing eye movement research institutes involve a relatively small number of sports projects and subjects. In the future, while expanding the number of research projects and the number of subjects, in-depth research will be conducted on specific and individual sports projects. Starting from the characteristics of athletes 'special cognition, it is the current and future trend of sports eye movement research to explore the special eye movement patterns and decision-making reaction capabilities, and to establish relevant theoretical models to explain and predict athletes' cognitive processes during special sports. One. In the field of sports eye movement research, the "expert-novice" paradigm is a well-recognized and widely used research paradigm. Using this paradigm can analyze the number of fixations, fixation times, and fixation positions of experts and novices through comparison between groups The difference between variables such as gaze trajectory and other important factors for cognitive decision-making, so as to explore the effective gaze model used by experts, and use the resulting model to train novices, so that they can improve the efficiency of decision judgment and action response faster. With the deepening of research, scholars have realized that there is a large gap between experts and novices, and it takes a long process from novices to experts. Therefore, only comparing experts and novices, the conclusions obtained are somewhat incomplete. To analyze the differences between experts and novices from a deeper perspective, it is necessary to set up an intermediate group, that is, subjects are divided into expert groups, general groups and novice groups to discuss the development process of the transition from novices to experts. In this way, the information obtained from the experiments of the two groups of subjects is more abundant, and the quantitative analysis is more detailed. However, adding an additional group of subjects increases the difficulty of experiment design and experiment operation. The experimental independent variables to be controlled increase, and the internal validity of the experiment is even more difficult to control. The combination of eye movement indicators and cognitive decision-making indicators to explore the internal processing of athletes' selection and judgment is another important trend in eye movement research. Eye movement indicators are behavioral observation indicators that reflect the external characteristics of eye movements. If they can be combined with cognitive indicators, they reflect the internal decision-making characteristics of athletes in rapid response situations. The eye movement model of cognitive processing, eye movement research will be more in-depth. But in the combination, it is necessary to solve the problem of simultaneous measurement of eye movement and cognitive decision-making process. The synchronous operation of the eye tracker and the recorder at the time of reaction will be an important link to achieve the synthesis of indicators. In addition, the eye tracker has research and application value in other fields such as: developmental psychology, pathological psychology, educational psychology and so on.

5 Conclusion

With the rapid development of science and technology, its application in psychology will become more and more extensive, and the design and manufacture of eye trackers will become more and more perfect. Nowadays, the enthusiasm for establishing eye movement laboratories in colleges and universities is gradually increasing. Therefore, it is foreseeable that the application of eye movement psychology and eye tracker will develop rapidly and well in the future.

References (References):

[1] Chen Xiangyang, Shen Deli. Eye movement study of the reading fable of primary and middle school students [J]. Psychological Science, 2004, 27 (4): 777-780.

[2] BerniceYL. TheAbcsofLearningDisabilities [M]. AcademicPress, 1996.

[3] Yan Guoli, Lv Yong. Eye movement study of rapid reading training for primary school students [J]. Tianjin Normal University News, 2004 (4): 27-30.

[4] Zhang Yunliang, Li Zonghao, Sun Yanlin, et al. Research on special cognitive eye movement characteristics of basketball guards [J]. Journal of Tianjin Institute of Physical Education, 2005, 20 (5): 39-41.

[5] Yan Guoli, Bai Xuejun. Application of eye movement recording method in sports psychology research abroad

[J]. Psychological dynamics, 1997, 5 (2): 44-48, 54.

[6] Bard, C., & Fleury, M. (1981). ConsideringEyeMovementasai. PredictorofAttainment. InCockerrillI. M. & McGillivaryW.ii. W. (Eds.), VisionandSport. StanleyThornesPublishers, Ltd.

Received date: 2008-10-23

About the author: Xu Jie, teaching assistant, currently teaching in the Department of Educational Science, Anyang Teachers College.

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