Unprecedented psychological analysis precision: Meet the eye tracking technology

Sergiy Danylov, Ph.D. in Neuroscience December 30, 2022

The eye-tracking technology has taken the world of evidence-based psychology by a storm. It has shown doctors that human psychological conditions can be diagnosed with enhanced precision, and what is more, personalization. Sounds weird and awkward, right? How can a human eye actually be used to tell how anxious or how likely to be anxious, or even suffer from an anxiety-related disorder, a person is? Basically, eye tracking allows us to observe and record human eye movement, and thus define specific gaze angles, which tell us a lot about what’s happening in your mind. In this article, we will tell you how eye tracking has become the core of Anima’s approach to setting a new level of psychological evaluations precision and personalization.  

No more suggestions

The main shift eye tracking brings to the domain of psychological evaluations is the personalization of results. There’s a need to understand that today’s standardized psychometric anxiety tests, for the most part, just let the respondents self-report the measure of their anxiety (Rossi & Pourtois, 2012). Needless to say, the output of such tests is often way more than biased. People are not used to being frank with themselves, especially when the topic of “discussion” is their mental health. 

Long story short, the standardized psychometric tests are based on suggestions of a respondent about his or her well-being. It seems fair to say that such an approach cannot be dubbed reliable when it comes to psychological assessment or diagnosis whatsoever. 

The eye tracking technology enables experimental assessment of the in-depth psychological processes, which were otherwise left at the mercy of the aforementioned suggestions built on the respondent’s self-reports. The usage of eye tracking in psychological research fostered the creation and validation of dozens of novice psychological assessment concepts, which have eventually enhanced the quality of the results received (Gegenfurtner, Lehtinen & Säljö, 2011). Observing and analyzing the eye’s response to various visual triggers can be more revealing than you might think it is.

How it works in psychology

Frankly speaking, eye tracking is not something new. Psychologists knew about the value it can bring to diagnosis back in the middle of the 20th century. Nonetheless, modern medicine is at the dawn of taking advantage of it, as the previous generations had no technological means to proceed with an accurate eye-tracking-based psychological evaluation. 

So, how does it work? One of the most prominent psychologists of the 20th century, a pioneer of the eye movement study, Alfred Yarbus was able to explain the core principle of eye movement back in 1967. In accordance with the scholar: 

Eye movement reflects the human thought process; so the observer’s thought may be followed to some extent from records of eye movement (the thought accompanying the examination of the particular object). It is easy to determine from these records which elements attract the observer’s eye (and, consequently, his thought), in what order, and how often.” (Wolf & Ueda, 2021).

Basically, eye movement reflects what’s going on in a person’s mind by mirroring back the reactions to particular irritants. Given the fact that human eyes can only ‘capture’ and focus on one (pretty limited) visual field at a time, the eye movement trajectory represents nothing else but a thin ray that depicts all the conscious and subconscious attention mechanisms at work in a human brain. You can find a visual representation of the angles a human eye uses to perceive various objects on Figure 1.

Figure 1. Human eye visual perception principles

In order to compensate for the lacking precision of peripheral vision, the gaze moves in leaps, which are called the saccades. Each saccade consists of three stages, which are i) movement; ii)stop; iii) focus. That is, the eye moves and it stops as soon as it is being impacted by an irritant and focuses on it to gather the information. Those pauses (stops) in eye movement are called fixations, as they give human organism the micro time slots needed for actually seeing, recognizing, and analyzing visual information. Figure two provides a visual representation of how the saccadic movement takes place.

Figure 2. A hypothetical scan path during a visual search task.

Above comes a scheme of a typical eye movement record of a subject carrying out a visual search task. First, the subject fixates on the central point of an otherwise blank screen. Then, as the display commences, his task is to search with his eyes for a red cross. During this experiment, conducted by Liversedge and Findlay (2000), the eye movement record has been superimposed on the viewed display, which, in its turn, showcases several fixations. The numbers you can see on the graph represent the duration of each fixation in milliseconds.

So what defines the duration of those pauses? Visual attention and the eye movement trajectory is being predicted by a phenomenon called salience, which is the convexity of the stimulus. In other words, the object’s physical shape impacts its psychophysiological meaningfulness for a human eye. Sure enough, the object’s vividness, color, and size also impact our visual attention. Nonetheless, the eye movement algorithm is, first of all, defined by the way we assess the content of the visual scene: its novelty, informativeness, appeal, and ambiguity. 

The movement of that thin ray mirrors back the habits and experience of the watcher. Thus, the psychologist can assess the watcher’s emotions and expectations, as well as their psychic conditions, by analyzing the gaze tracks (Clauss, Gorday  & Bardeen, 2022). However, eye tracking capabilities reach even further. The aforementioned visual response factor can help the researcher identify even the watcher’s temperament (Hoppe et al., 2018). In contrast to self-reporting or a mere eye movement observation, eye tracking provides a set of uninterrupted and utterly detailed information. 

Eye movement is one of the most sensitive indicators of the gnostic processes’ and functional states’ dynamics. Regardless of how simplistic it might seem, the connection between the psychic phenomena and eye movement is incredibly complex. For the most part, it is defined by the intricate process of eye movement planning, impacted by our brain’s multi-tasking capabilities.  

There is a large number of brain areas simultaneously taking part in eye movement management – from deep stem and subcortical cores to various cortical zones. The brain areas responsible for managing eye movement were described by scholars from the New York Academy of Sciences (Pierrot-Deseilligny et al., 2005).

Figure 3. Brain areas responsible for eye movement management

As we can see from Figure 3, there are at least 14 brain areas actively included in eye movement management. Hence, it becomes quite impossible to deny the fact that eye movement directly depicts the functional state of a human brain and the dynamics of nervous processes. 

How Anima harnesses eye tracking

Human attention – one of the core aspects of nervous processes taking place in a human brain – can be observed and defined by a number of eye tracking indexes.  Thus, when it comes to the analysis of projective tests, Anima assesses the following characteristics of the respondents’ eye movement behavior: 

  • First fixation on target stimulus;
  • First fixation latency on target stimulus;
  • Common dwell time on target stimulus;
  • Dwell time 0-500 ms on target stimulus;
  • Dwell time 500 ms + on target stimulus; 
  • Quantity of transit movement between stimulus;
  • Amplituda of saccadic movement;
  • Dwell time out of AIO (gaze out of images verges);
  • Dwell time  attention bias variability

Sure enough, the analysis capabilities are immensely dependent on the quality of the measuring tool. The web-based eye tracking usage provides us with information of tangibly lower quality than the high-cost professional eye-trackers would do. However, our research proves the viability of harnessing web-based eye tracking for precise anxiety analysis and even preliminary diagnosis (Semmelmann & Weigelt, 2018). One way or another, being a combination of evidence-based psychology, neurobiology, and technology, Anima’s approach takes a step forward in the direction of personalizing psychometric test results.

Furthermore, another research claims that the key factor defining the quality of the results that we get when testing online is the projection of the test tasks with regards to technological limitations and the respondents precision when following the instructions (Semmelmann & Weigelt, 2018). Hence, it seems that even the basic hardware can get the job done, if the instructions to follow are explicitly clear, which they are in Anima.

If you’re interested in diving deep into the technological capabilities of the eye movement tracker used in Anima, please follow this link.

Summing it all up

Even though it has been present in medicine since the middle of the 20th century, eye tracking has entered the spotlight of psychic research and diagnosing in the third decade of the 21st century. An impressive volume of empirical data based on hundreds of research studies proves that eyes are the best window into what happens in a human brain. That is why Anima’s core is eye tracking and not standardized psychometric evaluations. 


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