3/31/2023 0 Comments Itracking twIn those studies, researchers don't look only at the fixations and saccades, but more at other data that the eye trackers acquire.įor example, there is a lot of evidence that the higher the mental workload, the higher the blink rate and the greater the speed with which the pupil diameter changes. But also if it is too easy, then the work is boring and that can also lead to errors. If the tasks is too demanding then mistakes can be made, possibly leading to accidents. Cognitive psychologists working in that area are often interested in the mental workload of operators of vehicles and other machinery. That is the study of the interaction of people driving cars, piloting planes and so on. Human factors researchĮye tracking is also used a lot in human factors studies. The exact features used are complex, but in general children with dyslexia fixate longer on individual words and the saccades are shorter, which indicates that greater mental effort is needed to decode the individual words. If eye tracking is used, this can be increased to 95% after a single quick test. The traditional tests are also better at excluding non-dyslexic children than they are in correctly identifying dyslexic readers. Dyslexiaĭyslexia can be hard to diagnose using traditional methods, with accuracies typically of 70-80%, increasing to 90% with repeated tests. However, for cognates (words that are similar in both languages), that is less so - proving that there is a 'cross lingual overlap'. Normally bilinguals read the less dominant second language slightly slower. For example, in studies of bilingualism, researchers want to know if the vocabularies of the two languages are stored separately in the brain. That can be used to puzzle out the answer to all sorts of questions. If someone lingers on a word that they are reading, most likely they are having to think about it more. What can you use eye tracking for? ReadingĮye tracking has been used a lot to investigate reading. The advantage is that it can measure eye movements when the eyelids are closed, for example to detect the REM phase of sleep. As it is more invasive, it is used less often these days. There is also a third technique which uses electrodes attached to the skin next to the eye (electrooculogram, EOG). However, new techniques are being developed which use computer vision and machine learning to automate that. In order to know what it is that the subjects are looking at, the researchers normally have to manually label the video, which is a lot of work seeing there is a new image 25 or 30 times a second. So eye tracking glasses record a video of the scene in front of the glasses and combine that with the point of gaze of the subjects. In that case, instead of the scene that the subjects are looking at being fixed in relation to the camera, it is moving around. These days, head-mounted eye trackers are often in the form of eye tracking glasses. Multiple eye tracking cameras are normally used when the researcher is interested in 3D situations such as someone sitting in a car simulator. Remote eye trackers are often mounted under a computer monitor so that the system can work out where you are looking on the screen (when combined with screen capture) but they can also be in the form of a number of cameras placed in the scene. There are essentially two sorts of eye trackers head-mounted and remote. Fixations and saccades don't just occur during reading, they happen all the time. During a saccade, no visual information is transmitted to the brain. Where we stop and pay attention to a word, that is called a fixation and where we skip, that is a saccade. That area of focus corresponds to a small point on the retina of your eye called the fovea (about 2° of vision), and eye-tracking equipment uses that to determine what you are looking at. As your eye skips from word to word, your brain builds up a picture of the total scene and as soon as we pay attention to particular area, it springs into sharp focus. When you are reading a page of text, you don't see all the words in focus at once, just the one you are reading at that moment. With more complex analysis, it can give all sorts of information about a subject's mental state and the tasks they are carrying out. At its simplest, it records if someone looked at a given object or not. Eye tracking is a technique which records what you are looking at.
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