[apl]

As someone who works in visual neuroscience, this article's a tough read. Lots of statements that are semi-accurate at best.

1) Eyes don't work like cameras; there's no real "exposure" phase as such (even though there's lots of thresholds). So it's misleading to talk about discrete images that we sample at some fixed frequency. Instead, it's much more helpful to think of photoreceptors and subsequent processing stages as continuous band-pass filters. At some point, high frequencies are simply cut off because the electro-chemistry of the cell can't keep up. For us, that cut-off comes earlier than it does for invertebrates.

2) There's no mechanical interaction between light and photoreceptor. Instead, the transduction cascade of the dipteran eye seems to encompass a mechanical (as opposed to biochemical) step.

3) It's pure conjecture to talk about a fly's slowed down "perception" of the world. The reason why they take off before you get to them is much simpler -- there's a highly optimized reflex that connects eye and flight muscles via the giant fiber (a particularly rapid nerve). We have similar responses, like eye lid closing etc. Additionally, their photoreceptors are sensitive and fast. But there's zero evidence that flies have any sense of continuous time that could be faster than ours.

Ah, well. The perils of science journalism.

[taneq]

Thanks for the informed opinion. I know way less about animal vision than machine vision but the statement that eyes have a "frame rate" and "send images to the brain a fixed number of times a second" smelled really bad.

A maybe-dumb question about point (3) - I've noticed that when I get a blink/flinch response from something (usually some sand or a bug hitting my face when I'm on the bike), it feels like I blink just a split second before the thing hit me. Given that I'm unlikely to have any kind of precognition, do you think this might be related to the blink reflex being 'hard wired' and so my brain gets the "hey, a thing hit your face" signal after the "hey, your eyes just closed" signal? (Alternately, I read something once about our perception of audio being delayed by ~100ms so that it synchs up with our perception of vision, despite our visual processing being slower than audio - maybe the signal that caused the flinch gets 'buffered'?)

[apl]

> I've noticed that when I get a blink/flinch response from > something (usually some sand or a bug hitting my face when > I'm on the bike), it feels like I blink just a split second > before the thing hit me.

We know very little about conscious perception or even the locus at which sensory signals are integrated to generate a conscious percept. But it's perfectly possible that delays differ across modalities and that the proprioceptive signal about lid-closing reaches whatever-relevant-area before your visual system catches up.

> I read something once about our perception of audio being > delayed by ~100ms so that it synchs up with our perception > of vision

Not an expert on audition, but the brain is really good at generating coherent representations of the physical world across modalities. I wouldn't be surprised if such cross-sensory synchronisation happened in some form.

[taneq]

Cool, thanks for the response! I'm glad my theory doesn't sound /too/ far fetched. :)

[paublyrne]

(Alternately, I read something once about our perception of audio being delayed by ~100ms so that it synchs up with our perception of vision

If such a delay does occur it is considerably less than 100ml as that kind of latency would be very noticeable playing a musical instrument.

[nitrogen]

Is it possible that there is a delay for one-off unanticipated events, but the feedback loop we form between perception and playing is much tighter? I definitely have a hard time playing anything with much more than 5ms audio buffers myself.

[Retric]

Just to add the distance from a fly's eyes to it's flight muscles is very short which inherently reduces reflex time.

They might not view time faster, but they view and react to events much closer to the present.

[bayonetz]

How about an analogy to CPU clock speed, bus speed, etc.? I think that's really what the camera analogy is getting at -- the rate at which the signals are getting processed and acted upon. Clock speed / bus speed would similarly determine how high of frequency you could "hear" stuff if we were talking about ears instead of eyes. I know the computer model of the brain is way off in many respects but I find it pretty useful for stuff like this.

[throwitawayday]

On 3), the giant fiber is fast but not faster than other descending fibers. If anything, it is more reliable in its ability to signal.

See: https://www.nature.com/neuro/journal/v17/n7/full/nn.3741.htm...

Short abstract snippet (the "parallel circuits" are other, non-giant descending neurons that also trigger the escape behavior upon a looming stimulus):

"Intracellular recording of the descending giant fiber (GF) interneuron during head-fixed escape revealed that GF spike timing relative to parallel circuits for escape actions determined which of the two behavioral responses was elicited. The process was well described by a simple model in which the GF circuit has a higher activation threshold than the parallel circuits, but can override ongoing behavior to force a short takeoff. Our findings suggest a neural mechanism for action selection in which relative activation timing of parallel circuits creates the appropriate motor output."

[emerged]

If your brain and body spanned the size of the Earth, the signals into and within the brain would as a matter of physics take much longer than with a human. It seems reasonable to suppose this is also true when you compare a tiny fly with a comparatively massive human. That said, I haven't seen specific, explicit evidence to prove this seemingly logical theory.

[meowface]

Regarding point 3, I have no sources at the moment but have read several scientific articles in the past claiming that different organisms really do have a fundamentally faster or slower perception of continuous time, and also that drugs can temporarily influence this perception. Is there no truth to this at all?

[ChuckMcM]

Great! Any idea what mechanism adrenaline activates that gives the perception of time slowing down? That is something I've always wondered about having experienced it probably half a dozen times in my life so far.

[agumonkey]

Still what about non escape reflex sense of "time" ? Say like landing. Don't they perceive the world at a faster (or I should say systemically adequate for them) rate ?

[d13]

Yes this was my first thought after reading the article: no apparent evidence that these animals experience the passage of time at different rates.

[ScottBurson]

I'm really surprised at the resistance to this idea. Granted that we can never know another person's conscious experience, never mind another species', what reason could there be to think that it would be the same in this regard as ours? Seems to me the burden of proof falls more on that claim than on the claim that they're different, which I find completely plausible.