Eye tracking technique - Essay Example

?Eye tracking technique Part I: According to Poole and Ball (2005, p eye tracking is the technique of measuring an individual’s eye movements “so that the researcher knows both where a person is looking at any given time and the sequence in which their eyes are shifting from one location to another”. It is a technique which is often used to trace a person’s eye movements in order to assist human computer interaction (HCI) researchers in evaluating visual data processing and the elements which may affect the utilization of system interfaces (Poole and Ball, 2005). Through this tracking technique, the eye movements can be detected and considered as control signals in order to allow individuals to interact directly with interfaces without having to use a mouse of keyboard input (Poole and Ball, 2005). This is especially advantageous for individuals with disabilities. From the earliest days of tracking eye movements, various techniques have been used as tools of measurement. The earliest tools were the electro-oculographic techniques which used electrodes mounted on the skin surrounding the eye to assess the differences in the electric potential in order to measure eye movements (Poole and Ball, 2005). Large contact lenses around the cornea and sclera were also used in the past to track eye movements. Differences in the electromagnetic field based on the movement of the metal coil around the eyes were used as parameters in evaluating eye movements (Duchowski, 2003). These methods were however considered invasive; and a shift in the current non-invasive techniques was later seen. Most eye tracking techniques now use video images to track eye movements (Poole and Ball, 2005). In these video tracking techniques, the corneal reflections and pupil shape were used to track eye movements (Duchowski, 2003). Eye movements are important in the overall management of the visual system, and eye movement research relies on various diverse fields which are often beyond common perceptual tools (Richardson, 2004). Since there seems to be a major relationship between attention mechanisms, saccades have been considered as a source of insight in the cognition and language comprehension as well as the mental imagery of most individuals (Richardson, 2004). Eye movement research is a source of major interest in neuroscience and psychiatry, including advertising and design because these studies can establish consumer preferences. As eye movements can actually be managed voluntarily, and since they can also be tracked by appropriate tools, they can also be used “as a powerful input device, and have many practical applications in human-computer interactions” (Richardson, 2004, p. 2). In recent years, computer use and computer-based systems have increased. As a result, researchers have shifted their focus on eye movements in order to evaluate usability of certain products or items within sight (Tzanidou, 2005). Eye movements are considered as indicators of number of cognitive processing an image may require and how easy such image can be processed. This would then lead to the beneficial use of eye tracking in order to evaluate the use of user interfaces (Tzanidou, 2005). Eye movements can establish various patterns for scanning while navigation is being carried out by a user. Scan patterns are determined through the amount of fixations and their succeeding saccades (Tzanidou, 2005). Fixation refers to the process of focusing on a particular feature of an interface, it may last about 300-400 ms. At this point, cognitive processes are needed in order to comprehend such fixation. Data can be gained during fixation and higher fixations can imply a difficulty in gaining the much needed data from the image (Tzanidou, 2005). Eye trackers usually measure point-of-regard through the corneal reflection method (Goldberg and Wichansky, 2003). In this tracking, a standard desktop computer is often available, along with an infrared camera underneath the display monitor where image processing is carried out and qualities of eye during tracking is recorded (Poole and Ball, 2007). As light from the infrared camera enters and is reflected back from the retina, the pupil often appears bright. These elements are measured during eye tracking. Corneal reflection can also be carried out through the infrared light. As the software centres into the centre of the pupil as well as the place of corneal reflection, the vector between these two elements is evaluated and based on calculations, a point-of-regard is established (Poole and Ball, 2005). It is often difficult to establish point-of-regard through the corneal reflection; however, in evaluating the features of eye movements, it is possible to identify more specific results. The video eye trackers have to be well-calibrated to an individual’s eye movements and such calibration works through a dot displayed on the screen (Poole and Ball, 2007). As the pupil focuses longer on a particular area, the system records area where focus is made. After which, important details on areas of focus based on eye tracking can be established by the researcher. In the dual Purkinje image eye tracker, a similar pattern of eye tracking was also apparent. Light which bounces on the eye leads to various reflections, with the first and brightest reflection known as the corneal reflection (Richardson, 2004). The second image is often bounced off the rear surface of the cornea and the others at the front and the back of the lens. These four images manifest with different motions. The dual Purkinje image tracker evaluates the difference between the first and fourth images by shifting mirrors with servomotors (Richardson, 2004). The movement of the mirrors is related to eye rotation and is unaffected by head translation; the head however must be held steady with a chin rest in order to ensure eye detection by the equipment (Richardson, 2004). The Purkinje eye tracker is only controlled by the speed of the servomotor; otherwise, it is also fast and accurate. Part II Critical evaluation There are various benefits which can be seen in the use of eye tracking. Mainly, it provides data or records on the pattern or fixations or the scan paths, the time allocated in looking at various images, and the deployment of visual attention (Namahn, 2001). It is also much favoured because eye tracking has been known to present detailed and quantitative information on the usability assessment process (Cornelissen, et.al., 2002). With eye tracking, it is possible to support traditional findings and establish a better understanding on the efficacy of interface design (Ogunbanjo, et.al., 2007). This kind of technology would likely impact significantly on computing as it would allow users to effectively assess the areas where people focus. In the current age of computers and computer technology, eye tracking can help in developing websites and in spreading or managing information on the web. It is also a valuable, but also cost-effective tool in testing usability and in carrying out task-based observations (Ogunbanjo, et.al., 2007). Eye tracking is an important test usability tool because eye movements are faster than the existing input media, and there is no specific training required before normal users can utilize or apply it (Ogunbanjo, et.al., 2007). With eye tracking it is easier to detect user interest; moreover it helps users interact with their environment. This technique is also crucial during videoconferencing as it can ensure eye gaze correction. It can also promote the efficiency of controllers’ effectiveness, as well as reduce the dangers of air traffic displays (Ogunbanjo, et.al., 2007). For video game developers and graphic artists, eye tracking is also a beneficial tool; in addition, website developers can also use this technique for their designs and styles. For computer conceptualists and researchers, they can use this technique to evaluate their work and their impact on the consumer; it also tells them their weaknesses and areas where they may need to improve. It is an easy enough technique to use because no complicated hardware is needed to apply and interpret it. It is also an intuitive interface and provides real-time feedback for the users (Ogunbanjo, et.al., 2007). There is also an element of flexibility in its application as there are various operation modes to choose from. These qualities help make this method a very useful and user-friendly technique. Inasmuch as it brings about a variety of benefits, this technique also has difficulties and unresolved issues. For one, some individuals cannot be tracked through this technique because the eye may not reflect enough light or the iris may have a very light colour which cannot be distinguished from the reflection of the pupil (Ogunbanjo, et.al., 2007). Some users may also be difficult to track because they are wearing glasses or hard contacts; and if they can be tracked, their eyes may be dry during the testing and may therefore be hard to track. Issues with its use also refer to the fact that equipment used in this technique is expensive (Sandhu, et.al., 2007). Not many companies have opted for this technique because of its cost. Costs also have to be allocated in training individuals on how to use it. Moreover, calibrating this equipment often takes up much time and it can sometimes cause the user to deviate from its use (Sandhu, et.al., 2007). There is also an issue which relates to the accuracy of the results from eye tracking. This method does not often take into account involuntary eye movements, including passive and non-command eye movements. Experts define this as the “Midas Touch” problem where there is a non-discrimination of data ‘touched.’ Another issue in its use relates to the eye being a computer input device (Sandhu, et.al., 2007). Eye movement is most often than not a very unintentional act. For the most part, it is difficult to actually control eye movement and position at all times. And yet each eye movement, whether intended or unintended is tracked and recorded. As a result, the information being recorded by this technique may not always yield accurate results. Part III Psychology: Cultural variation in scene perception In relation to my current psychology practice, eye tracking may provide various benefits. Eye tracking techniques allow students as well as researchers to adequately monitor behaviour which presents signs of attention (University of Portsmouth, 2011). Visual psychophysics studies have been used in order to evaluate attention, object recognition, face recognition, scene perception, infant social engagement, and the detection of deceptive behaviour among witnesses (University of Portsmouth, 2011). For the most part, I find this technique beneficial because it helps provide me with cues in understanding and detecting patient reactions, their sincerity, as well as their perceptions. There are also cultural differences inherent in every person and these differences also cause visual reactions and perceptions to be interpreted in different ways. Culture also impacts on how faces are perceived (Miellet, et.al., 2010). Studies by Miellet, et.al. (2010) have revealed that whites or Caucasians often focus their perceptions in the eye region in order to establish facial recognition; on the other hand, Asians focus more on the nose. Despite these differences on focus areas, the perception and recognition of both groups is more or less the same and registers at more or less the same time. This is an important detail because it indicates that facial recognition activities can be gained through a variety of fundamental scan paths. And yet, these results are puzzling when evaluated alongside results for Asian respondents who use different tools in facial recognition patterns (Miellet, et.al., 2010). Culture in effect, shapes perception in various perceptual activities including scene perception, description, as well as perceptual categorization. Apparent in some observations is the impact of the culture of recognition (Miellet, et.al., 2010). Americans often considered focal objects earlier than the Chinese; on the other hand, the Chinese were able to come up with details about the environment at a faster rate than their American counterparts. The East Asians were not likely to correctly identify old focal objects when framed under a different and unfamiliar background (Miellet, et.al., 2010). The main idea of the holistic and analytic perception of culture is the fact that East Asian tend to focus on the holistic impact of relationships when trying to understand their environment (Nisbett and Miyamoto, 2005). The Chinese Asian culture is not one which sees a person eye-to-eye. Hence, this may impact on how eye tracking and facial perceptions are carried out. Eye tracking and movements can also present differently based on the culture of the user. Easterners and Westerners are usually miles apart in terms of their interpretation and focus (Chua, Boland, and Nisbett, 2005). Americans often manifest a faster time in recognizing objects because they tend to focus on the object when presented with it. For the Asian however, he tends to look at the background first, including the environment where the object is found. In effect, cultural differences in visual memory are mostly attributed to how people from varying nationalities and culture perceptive scenes (Chua, et.al., 2005). Cultural differences in the eye movements and tracking, as well as facial recognition, and scene perceptions can come from various sources, which may include differences in experience, expertise, as well as social exposure. It is therefore easy to use such elements in high-level recognition; however since these elements can impact on the allocation of attention, they also impact on lower levels of cognition (Chua, et.al., 2005). It is often safe to assume that varieties in attention given to context and object are based on socialization techniques. This can be likened to child-rearing activities where societal differences also have different end-impact. East Asians are often known to exist in a complex and rich social environment where their roles are already defined. Placing much attention to context is therefore crucial to effective functioning (Chua, et.al., 2005). On the other hand the Westerners often exist in less restrictive social environments where independence is given high premium; this environment also prompts them to give less attention to context or to the environment. Tracking eye movements have also found their place in terms of attentional capture by emotional content (Nummenmaa, et.al., 2010). Using manual response latency techniques have established a basis for attentional bias based on the stages of attention orienting: disengagement of attentional focus; shift of attention towards new image; and engagement in the new object. Studies using cueing tasks with emotional images have illustrated the bias in attentional engagement based on emotional content, sometimes with angry faces or complex images (Nummenmaa, et.al., 2010). The bottom line is that under the eye tracking system, if an emotional image gains attention, the probe which would replace it would respond faster as compared to when a neutral image is used. In effect, anxious individuals have been known to respond quickly when a dot replaces an angry face. Studies therefore support the notion that in tasks required for target stimulus, using schematic angry faces tends to create a faster and more imminent response (Nummenmaa, et.al., 2010). As a psychologist, presenting more stimulating images would often create a faster and more vivid response from patients. On the opposite end of the picture, patients who manifest with a more powerful or reactive response imply a more affected and deeper response, one which often prompts more assessment and review. 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