24 replies to this topic

[25585]

A natural reaction to being scared &/or startled is eye pupils dilating wider than normal, along with other physical reactions.

 

A perceived danger the other night made me jumpy, and before I calmed down to normal, my night vision saw more in that hyper-alerted physical state than I normally could. 

Edited by 25585, 19 June 2025 - 06:05 AM.

[Astrojensen]

I refuse to run around scared at night, just to see those pesky Abell planetaries. 

 

 

Clear skies!

Thomas, Denmark

[Alex.C]

The good news is that autonomic pupillary dilation can also be triggered by other psychophysiological states, such as arousal.

More proof that a supportive spouse isn't just handy when you want to buy new eyepieces.

[cjarvis64]

The good news is that autonomic pupillary dilation can also be triggered by other psychophysiological states, such as arousal.

More proof that a supportive spouse isn't just handy when you want to buy new eyepieces.

Bravo 

[zoso916]

The good news is that autonomic pupillary dilation can also be triggered by other psychophysiological states, such as arousal.

More proof that a supportive spouse isn't just handy when you want to buy new eyepieces.

Over the years I've dated many attractive women that I was terrified of.

[rachnoman]

I'm afraid of the dark.

[hyiger]

When my wife comes out to check on me my pupils dilate. I also had some "stuff" in college that would make my pupils dilate as well. 

[K-night]

Many decades ago I spent nights beside a gigantic satellite tracking camera. The camera operator would share stories about "them" looking at "us" while "we" looked at "them", and I vividly remember how dazzlingly expansive the sky became as my hair stood on end.

[Jon Isaacs]

I refuse to run around scared at night, just to see those pesky Abell planetaries. 

 

 

Clear skies!

Thomas, Denmark

 

In my experience, large dilated pupils are rarely an advantage... Very few objects are seen better with a 7 mm exit pupil than with a 6 mm exit pupil.

 

Edit: I should have said:

 

Nearly all objects are seen best with exit pupils smaller than you fully dilated pupil. Usually far smaller is optimal.

Jon

Edited by Jon Isaacs, 19 June 2025 - 12:07 PM.

[areyoukiddingme]

This makes evolutionary sense--contrast sensitivity should go up rapidly under conditions of threat detectcion.

 

Indeed, simply viewing a face with a fearful expression increases contrast sensitivity.

 

https://journals.sag...ixFR6dngAVG3NN-

 

The effect may be neural rather than caused by pupil dilation, but given that pupil dilation seems to be part of the mechanism, I would think it plays a role.

 

I haven't gone down the rabbit hole on this area (there are thousands of papers), but it's likely a complex mechanism. One thing that comes up is spatial frequency--i.e., the contrast sensitivity enhancement is for low spatial frequencies. So if fear faces were used, it should make seeing detail harder (e.g., spiral arms in a low mag galaxy), but making a detection easier (e.g., seeing the galaxy at all). 

 

I also don't know enough about the size of the effect, but if the mechanism is evolved for threat detection, it should actually be something that makes a difference. 

 

My guess would be that two major selective pressures on our ancestors would be detecting animals in low light that hunt, as well as other humans. Both have a bad habit of killing us.

[Jon Isaacs]

 

My guess would be that two major selective pressures on our ancestors would be detecting animals in low light that hunt, as well as other humans. Both have a bad habit of killing us.

 

It's hard to imagine that adrenaline affects the Rhodopsin in your eye which is the primary source of low light vision. 

 

In a fearful situation, quick dilation is doable and and offers at least something. 

 

Jon

[Bill Weir]

Adrenaline increases neurotransmission. It could allow a weak light signal easier flow along the optic nerve. It has been shown to allow increase vision in low light situations. Too much though and for too long a period leads to decreased positive effect. Adrenaline also increases blood sugar levels which is needed to maintain the increased alertness it also stimulates. 

 

Bill

[csrlice12]

All you need to remember, if Godzilla shows up....RUN.

[areyoukiddingme]

It's hard to imagine that adrenaline affects the Rhodopsin in your eye which is the primary source of low light vision. 

 

In a fearful situation, quick dilation is doable and and offers at least something. 

 

Jon

 

Yes, that's why I said I think the effect is likely based on neural processing of signal rather than the eye. But I don't know enough physiology to have a strong opinion about how quickly the eye can react. 

 

The evidence I've seen shows effects for diffuse objects, so my bet is that people's contrast detection is specifically around picking up movement, and thus contrast of an object against a background. That makes a lot of evolutionary sense as it's easy to see how a functional mechanism could respond to that kind of pressure, and that those with the mechanism for quick reaction would survive more frequently than those with lesser/slower reactions. 

[WISDOC]

  I'm not afraid of the dark. I'm afraid of some things in the dark!

[WISDOC]

Always remember. Having your eyes to the heavens is fine, but it's  what's on the ground that's gonna get you.

 

  Clear skies and keep looking up.  Doc

Edited by WISDOC, 19 June 2025 - 08:51 PM.

[triplemon]

So you say - its climbing that ladder in the pitch dark, on uneven ground, that makes the aperture truly usefull?

 

Low power needs high vantage points?

Edited by triplemon, 20 June 2025 - 02:16 AM.

[EmDrive2821]

While the fight or flight response increases pupillary dilation, awareness and cognitive function, there are many other effects that are not conducive to the detailed extended observation and study of astronomical targets. 
 

It is also understood that high levels of adrenaline release, or sustained release, may result in a cognitive decline.

 

I think that the benefits of normal adrenal gland function when observing, far outweigh any advantage of an adrenaline rush. 

 

If one wants to experience viewing with a maximally dilated pupil, consult with your eye care provider.  There are several commonly utilized dilating agents that are safe for most everyone, that would allow the observer to experience the effects of a large diameter fixed pupil.  Remember, this would also negatively impact accommodation, requiring most individuals to use reading glasses for near viewing, while the dilating agent is in effect.

 

Gary

[Kefka1138]

So you say - its climbing that ladder in the pitch dark, on uneven ground, that makes the aperture truly usefull?

 

Low power needs high vantage points?

That "hold my beer" ladder looks wildly precarious and is giving me the sweats. 

Edited by Kefka1138, 20 June 2025 - 11:08 AM.

[csrlice12]

Luckily he has the ground to break his fall....and possibly his arm or leg as well.

[WISDOC]

  I think in triplemon's case it's the ground that is gonna get him.  Be careful, man !

[25585]

It's hard to imagine that adrenaline affects the Rhodopsin in your eye which is the primary source of low light vision. 

 

In a fearful situation, quick dilation is doable and and offers at least something. 

 

Jon

Cats eyes can dilate wide in a fraction of a second. Their vision is geared to movement.

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[Redbetter]

 

 

That "hold my beer" ladder looks wildly precarious and is giving me the sweats. 

 

The three legged nature of an orchard ladder is fundamentally more stable than a four legged ladder.  It is very difficult to keep four points of contact across a surface, even one that is nominally flat (as when we shove silverware under the leg of a table at a restaurant so it stops wobbling), but three points of contact are a natural/simple solution.  An orchard ladder relies on a wide splay to the legs with the steps, to maintain sufficient balance.  As long as these are not placed on too much of an incline relative to one another, this will be fine.You don't want to lean so far out on a slope that the center of gravity surpasses that of a leg.

 

The negatives are that one can still do something stupid like stepping off the side into thin air, and of course it isn't practical to have a tray positioned on these for eyepieces and the like.  I have had to catch a full grown man who stepped off the side of my platform ladder at a dark site when he was done looking at the target high overhead.  I would say I only did so to prevent him from injuring himself, but in truth I also saw that he was grabbing the side of the ladder and would dump the eyepieces if I didn't arrest his fall first.

[ccate]

But I think I've read here that dilation takes seconds, but dark adaptation not. The two are not the same.

[WillR]

Cats eyes can dilate wide in a fraction of a second. Their vision is geared to movement.

I think your avatar photo is making my pupils dilate.

 

Speaking of cats, I make a point of never observing with them any more. Not since the last one, who kept training the scope on 15th magnitude galaxies, and then asking me in a sarcastic tone: “You can’t see that?”