[time-nuts] Re: Clock displays -- eye response

[Jeremy Nichols]

“ neat illusiions if you put a dark filter over one eye. “

The Exploratorium in San Francisco once has an example using an “inverted
pendulum,” a ping-pong-sized ball on a rod that was waved back and forth by
some mechanical means. Surrounding it were vertical strips of dark plastic
(ND = perhaps 1?) with equal-sized empty spaces between. If you stood so
you looked through the dark plastic with one eye and the empty space with
the other, the pendulum appeared to trace out a cone in the air, going
‘round and ‘round instead of just back and forth. It made an impression
that has stayed with me for 30 years.

Jeremy


On Sat, Dec 11, 2021 at 2:00 AM Hal Murray <halmurray at sonic.net> wrote:

>
> Erik E. Fair said:
> > This apparently relevant paper is, alas, behind a paywall:
>   ...
> > The magic (google-fu) word is "latency" ...
>
> Ah... Thanks.
>
> NIH should have a lot of papers on visual stuff,
>   so I fed >pubmed visual latency< to Google
> That got a bunch of hits.  Some are behind paywalls.
>
> This looks like more than I wanted to know:
>
> Event timing in human vision: Modulating factors and independent functions
>   https://pubmed.ncbi.nlm.nih.gov/32853238/
>
> SOA is a magic TLA: Stimulus-onset asynchrony
>   https://en.wikipedia.org/wiki/Stimulus_onset_asynchrony
>
> The ballpark from the graphs is 30-50ms depending on accuracy.
>
> Along the way, I learned about Pulfrich
>   https://en.wikipedia.org/wiki/Pulfrich_effect
> The latency depends on brightness.  You get neat illusiions if you put a
> dark
> filter over one eye.
>
> From Wikipedia:
> > The Pulfrich effect has typically been measured under full field
> conditions
> > with dark targets on a bright background, and yields about a 15 ms delay
> for
> > a factor of ten difference in average retinal illuminance.[7][8][9][10]
> These
> > delays increase monotonically with decreased luminance over a wide (> 6
> > log-units) range of luminance.[7][8] The effect is also seen with bright
> > targets on a black background and exhibits the same luminance-to-latency
> >
>
-- 
Jeremy Nichols
Sent from my iPad 6.