[NNagain] Fwd: separable processes for live in-person and live zoom-like faces

[Dave Taht]

sending again as my server acted up on this url, I think. sorry for the dup...

---------- Forwarded message ---------
From: Sebastian Moeller <moeller0 at gmx.de>
Date: Fri, Nov 17, 2023 at 3:45 AM
Subject: Re: [NNagain] separable processes for live in-person and live
zoom-like faces
To: Network Neutrality is back! Let´s make the technical aspects heard
this time! <nnagain at lists.bufferbloat.net>
Cc: <joy.hirsch at yale.edu>, Dave Täht <dave.taht at gmail.com>


Hi Dave, dear list

here is the link to the paper's web page:
https://direct.mit.edu/imag/article/doi/10.1162/imag_a_00027/117875/Separable-processes-for-live-in-person-and-live
from which it can be downloaded.

This fits right in my wheel house# ;) However I am concerned that the
pupil diameter differs so much between the tested conditions, which
implies significant differences in actual physical stimuli, making the
whole conclusion a bit shaky*)... Also placing the true face at twice
the distance of the "zoom" screens while from an experimentalist
perspective understandable, was a sub-optimal decision**.

Not a bad study (rather the opposite), but as so often poses even more
detail question than it answers. Regarding your point about latency,
this seems not well controlled at all, as all digital systems will
have some latency and they do not report anything substantial:
"In the Virtual Face condition, each dyad watched their partner’s
faces projected in real time on separate 24-inch 16 × 9 computer
monitors placed in front of the glass"

I note technically in "real-time" only means that the inherent delay
is smaller than what ever delay the relevant control loop can
tolerate, so depending on the problem at hand "once-per-day" can be
fully real-time, while for other problems "once-per-1µsec" might be
too slow... But to give a lower bound delay number, they likely used a
web cam (the paper I am afraid does not say specifically) so at best
running at 60Hz (or even 30Hz) rolling shutter, so we have a) a
potential image distortion from the rolling shutter (probably small
due to the faces being close to at rest) and a "lens to RAM" delay of
1000/60 = 16.67 milliseconds. Then let's assume we can get this pushed
to the screen ASAP, we will likely incur at the very least 0.5 refresh
times on average for a total delay of >= 25ms. With modern "digital"
screens that might be doing any fancy image processing (if only to
calculate "over-drive" voltages to allow or faster gray-to-gray
changes) the camera to eye delay might be considerably larger (adding
a few frame times). This is a field where older analog systems could
operate with much lower delay...

I would assume that compared to the neuronal latencies of actually
extracting information from the faces (it takes ~74-100ms to drive
neurons in the more anterior face patches in macaques, and human
brains are noticeably larger) this delay will be smallish, but it will
certainly be only encountered for the "live" and not for the in-person
faces.


Regards
        Sebastian

P.S.: In spite of my arguments I like the study, it is much easier to
pose challenges to a study than to find robust and reliable solutions
to the same challenges ;)


#) Or it did, as I am not directly working on the face processing
system any more
*) Pupil diameter is controlled by multiple factors, ranging from its
"boring" physiologic function as adaptive aperture the visual system
uses to limit the amount of light hitting the retina, to some effect
of cognitive processes or states of the sympathetic nervous system see
e.g. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6634360/ the paper,
IMHO does over play the pupil diameter reasponses by not acknoledging
that these might result from things as boring as not having the true
faces and zoom faces sufficiently luminosity matched.
**) Correcting the size of the projected image to match in degrees of
visual angle only gets you so far, as we do have some sense of
distance, so the same visual angle at 70cm corresponds to a smaller
head/face than the same visual angle at 140cm... this is both
nit-picky, but also important. I also note that 70cm is at the edge of
a typical reach distance, while 1.4 m is clearly outside, yet we do
treat peri-personal space with-in effector reach differently from
space beyond that.


> On Nov 16, 2023, at 22:57, Dave Taht via Nnagain <nnagain at lists.bufferbloat.net> wrote:
>
> Dear Joy:
>
> good paper that extends the idea of zoom fatigue into something closer
> to zoom-induced somnolence. Thanks for doing this kind of detailed
> measurements!
>
> I would be very interested in a study of brain activity while varying
> latency alone as the variable for videoconferencing. One being say, a
> live video feed between the participants (0 latency) vs zoom (at
> 500ms), or with one jittering around, or one at, say 60ms vs 500ms. I
> tend to be much happier after a day using "galene.org" which tries for
> minimum latency than zoom, and still find my ability to interact
> quickly across a dinner table hard to get into after too many hours on
> it. Are y'all pursuing further studies?
>
> The link to the paper is mildly puzzling in that the token is
> required, and I am assuming that perhaps it is generating a
> watermarked version differently on every download?
>
> https://watermark.silverchair.com/imag_a_00027.pdf?token=AQECAHi208BE49Ooan9kkhW_Ercy7Dm3ZL_9Cf3qfKAc485ysgAAAzQwggMwBgkqhkiG9w0BBwagggMhMIIDHQIBADCCAxYGCSqGSIb3DQEHATAeBglghkgBZQMEAS4wEQQMBvAQsisJ_ABhWglzAgEQgIIC5womb1HIyE-rX0v_xte9EwVGyabIjMO6g80txKAFqHmQPVEv7FostAfIK-4yXUZnSyLivNxp6pummVVwxB_kCJEyG2DtAH2R8ywkWTTjGw22vpotfz5injZM6fMRQNyTq8dcjtMTTFpEjbsrbupEoMFo7Z0wxqV8bmbPD8xO6hu1T8I8gg5579PZNHt7-PMNgqJVlEaxPY3nMvc1XkKYdh1RIhFetQkAdhhro2eWfu_njMvzdRWVeN2ohY6OnSJSDljWiWxyUOqnKX6tps2XFtVBWUh2sE3HK-EsI-w0EmpBlAC7huyQsXkXW7tmPOwA7yiGQm4uSfcOn_EKGhvzhjHsdP8Mm1QJat6_rWSPZZGwhFzPB2Wl92DDfiSOesKKQBv_OvmGc3FUmFAhqIeAlzlyNkdBydk2hQqvS46OTGfdBEvwpIH_AZclDiLeuyJPP5v2YaoByFQ7w4uXHMyNhEo5mR2_pQ3WM7CpzknZixRvA5TQySW830iH0k00QZwt6a3nphgV6R4int5Pl-QdmCKzFoJ2EuPIBKvG9H5yBq18E6r1jyk1mdFKpo0-OEpLNIBpGm-1SomHw2qo5uCRWoAW6MO7K-sKZokirXGgJ7rIdRznq3BXvYxFKVn7tqJlIAAX6qDrC0bkefj8PEweuk2zIraj1Ri3otbdX3h0zBsKgmdY6qiOn8LtyxIy3vvXLnbiaIColztgAt1cHuI6b0w3rLg7BGSE2cetBDTyGS9OS0NKq91xqljwDAZBFkuKwtfYLzxIeeBy4KrG-PBqGtUEholGjHHyKCwxytw12qvgrTjdX7cXhYJSrs-HBJtRgiP5Yb6DJAQrlqEKeGnyTlPv2o3jNVvT0CZ9zWX8Qm0O6wiGo1PqpxCM3VLw0VXVsWcHJ39eLYN30GuHznYCaH5INdtgZoJdQbmZO3o_tF7itz1uYHItxNK_ZQ3oFKoUQd0e7sx51xaFj6VnNNo39Ms3mdyEQOEp
>
>
> --
> :( My old R&D campus is up for sale: https://tinyurl.com/yurtlab
> Dave Täht CSO, LibreQos
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-- 
:( My old R&D campus is up for sale: https://tinyurl.com/yurtlab
Dave Täht CSO, LibreQos