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See a world

A study examined the way in which different subjects - healthy, with depression or attention disorder - choose to look at the world

Is it our mood that affects the way we look at the world or vice versa? It is possible that our eye movements can help answer this. Like other muscles in the body, the eye muscles are controlled by the central nervous system. The motor commands that come from the cerebral cortex pass through the brain stem and reach the eye muscles through three cranial nerves. Thus, through the action of muscles connected to the eyeball, the eyes move in different directions.

Prof. Yoni Pertsov from the Department of Psychology at the Hebrew University comes from the world of brain research and studies vision and eye movements in the general population and in special populations, such as people with depression, Alzheimer's, Attention Deficit Hyperactivity Disorder (ADHD) and prosopagnosia (difficulty processing and recognizing faces). According to him, "Sight is the main sense through which humans receive information about the world, and it is still not entirely clear how it affects their behavior." In his research, he tests, for example, short-term visual memory (what people see and what they remember from it for a few seconds) and characterization of eye movements. "There is a difference in eye movements when looking at familiar and unfamiliar objects. When we look at familiar faces for example, we scan them much less and therefore move our eyes less. Our gaze is fixed longer. In addition, the eye is drawn to the familiar object out of several objects, it is almost uncontrollable. And of course there is also an applied aspect to all of this, for example, a tool in the investigation of crimes," explains Prof. Pertsov.

In their latest research, which was supported by a grant from the National Science Foundation, Prof. Pertzov and his team wanted to check if people who are in a similar situation and look at identical stimuli scan them differently and why. According to him, "There are people who focus more on the face and there are those who focus on other objects. The question is what this difference comes from, why it is related to the person's character and how it affects him. Maybe those who focus on the face are more influenced by the way they are looked at? It is a consistent behavior that is interesting to investigate and understand what it expresses. It's easier to understand this in the context of people who suffer from depression, for example, who tend to look more at sad and less happy stimuli." One of the pictures shown to the subjects in the experiment.

As part of the study, 100 healthy subjects (students) and subjects with clinical depression treated at the Sheba Medical Center were examined in Prof. Pertzov's laboratory. All the subjects sat in front of a screen where two pictures were shown at a time, on the right and on the left, one positive and one negative (for example happy versus sad faces and tasty versus rotten food). A computerized system called Eye Tracker tracked one of their eye movements, according to the position of the pupil and the reflection of light on the retina, and thus it was possible to know which image they looked at longer each time.

It was found that the healthy subjects looked more at the positive stimuli, compared to the depressed subjects who looked at both the positive stimuli and the negative stimuli approximately equally. After that, the subjects with the depression received drug treatment for about two months and the experiment was conducted a second time. It was found that this time they looked more at the positive stimuli. In the healthy subjects there was no change. "From this we can understand the two-way relationship in which the mood affects the choice of what to look at, and this choice affects the mood. It expresses who we are and how we look at the world. Thus, it is possible that if we trust people to look at the world differently - we will lead to a positive change in them, and we intend to investigate this later."

In another experiment Prof. Pertsov and his team examined students, with or without ADHD. They watched videos of a car driving down the street and were required to follow it with their eyes. Here, too, their eye movements were tested with the Eye Tracker. It was found that the subjects with attention disorder (especially those suffering from hyperactivity) focused less on the car and more on the distractions in the background (such as people walking and birds flying), compared to the other subjects. "This is another example of how people who are in the same situation can react to it differently. In addition, we have found here an objective and fast tool for quantifying the tendency to distraction, which can help diagnose attention deficit disorder."

Relaxed people can understand the two-way relationship where mood affects the choice of what to look at, and this choice affects the mood.

The researchers also shot a video at the central station in Jerusalem with a 360-degree camera in which a homeless person is seen lying on the sidewalk and projected it to the students using virtual reality technology. Now they intend to test the length of time they looked at the homeless person and its relationship to their level of empathy.

Life itself:

Prof. Yoni Pertsov, 45 years old, married with three children (6, 9, 12), lives in Tel Aviv. Likes to travel, read and play chess.

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