How our vision works in stressful situations

2024 Author: Malcolm Clapton | [email protected]. Last modified: 2023-12-17 03:44

Aaron Kuan, the author of this post, served in the US Army and National Guard, continued in the private contract business. Then he became a patrolman at the Ministry of Defense and a member of the special response group, was nominated as the leader of this group and instructor of the sniper group. Aaron is currently an instructor at Sage Dynamics. This person knows firsthand how our vision works in a stressful situation.

I fumbled for my pistol and yanked it out of the holster. My first shot was from the hip. The bullet hit him in the stomach, just above the waist. I expected him to fall. Now I understand how stupid it was. He fired before or after I pulled out the pistol. I didn’t feel it, I don’t think it felt. I just stretched out my arms and fired. Later I was told that I fired 12 shots.

I moved and looked for cover. I thought my weapon was out of order or the bullets were getting stuck in the barrel. I haven't heard anything. All I have seen is his weapon. Then he fell. I recharged automatically. It didn't happen as I expected. I didn't see the scope at all. I don’t remember what my grip was, the stance … Perhaps my previous training helped, but I can’t say for sure.

K. P. policeman after his first shootout

1. In case of a sudden threat, were you able to get a clear enough sight picture?

No - 90%.
I don't remember - 9%.
Yes 1%.

2. Could you consciously focus and find your scope?

I didn't have time - 33%.
No - 31%.
Yes - 23%.
I don't remember - 13%.

3. Were you able to involuntarily aim at any point in the script?

No - 65%.
Yes - 20%.
I don't remember - 15%.

Pistols used: Beretta 92 and Glock 17 with OEM Beretta, OEM Glock, Glock Night Sights, Truglo TFO, XS Big dot, Trijicon, Trijicon HD, Sawson Precision (fiber optic front) sights.

Previous student shooting experience:

0-5 years old - 20 people;
6-10 years old - 45 people;
11–20 years old - 28 people;
21+ years - 17 people.

In all my formal training, no one explained to me why I do not see the sight under severe stress in real situations, until I read "Treatise on Physiological Optics" by Hermann von Helmholtz. From physiology: the accommodative apparatus of the eye provides focusing of the image on the retina at a speed of between 350 milliseconds and 1 second, depending on age, general eye health and the environment, through tension (focusing on distant objects) and relaxation (focusing on close objects) of the ciliary muscle of the eye …

In a stressful situation, the sympathetic nervous system is activated. There is an instantaneous release of adrenaline into the blood, the ciliary muscle tense and changes the lens of the eye for distant focusing. This is why it is almost impossible to focus on objects near the eyes when under great stress.

It also expands the pupil, which allows it to transmit the maximum amount of light and thus better see the target. But this leads to tunnel vision, in which a person loses peripheral vision.

Loss of peripheral vision is also due to the level of training and previous experience. But in any case, you can expect a loss of 20 to 30% of the 190 ° (average 155 ° per eye) horizontal view.

Our vertical field of view is 60 ° above the line of sight and 70 ° below it. With tunnel vision, the loss of vertical vision can be up to 40%.

When activated, for example due to an external stimulus, the sympathetic nervous system and compression of the ciliary muscle of the eye, a loss of depth perception occurs. This is due to a displacement of the visual axis (the line connecting the anterior and posterior poles of the eyeball) and contrast problems between each eye. This leads to the fact that the threat may seem closer than it really is. Although this loss is negative, it also has a positive side - it contributes to better processing and recognition of threats.

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