
The Liar's Walk: Detecting Deception with Gait and Gesture - DyslexicAtheist
https://arxiv.org/abs/1912.06874
======
ggggtez
>However, in the deceptive condition, the confederate is wearing the same
hoodie with the hood pulled up while wearing sunglasses.

Yikes. Anyone getting a feeling of some racial bias in this experimental
setup?

[https://www.dailytarheel.com/article/2018/04/diversity-0426](https://www.dailytarheel.com/article/2018/04/diversity-0426)

>As of fall 2017, UNC-Chapel Hill had a 7.8 percent enrollment rate for Black
students, one of the lowest in the state, while just over 22 percent of
residents in North Carolina are Black.

Not to mention, there doesn't seem to have been any _control_ in this
experiment. What a bunch of nonsense. These students were told to act sketchy,
and predictably probably hammed it up to please the experimenters (see: they
stuck their hands in their pockets, looked around a lot, etc).

~~~
lewiscollard
You are entirely right.

I am scared that our "AI" (really ML) future will be ML trained from bad data
and it's pre-crime-fun for anyone that just acts a bit weird or tries to not
stand out too much.

I hope there are enough people like you in the institutions where it matters
to be all "hey, wait a fuckin SECOND here".

~~~
wnkrshm
Yeah, like people with high functioning autism spectrum disorder who need to
mask themselves. Or people with anxiety disorders who may just freak out
internally about looking nervous. Lots of examples.

~~~
Fnoord
I have autism (previously diagnosed with anxiety disorder), so I thought I'd
fit this one, and indeed I do. I wear hoodies (pref. ski sweaters) practically
throughout half the year. They help prevent rain and cold on my head, and
allow me to reduce external senses. Ski sweaters allow me to protect my hands
from cold and dirt.

I also wear glasses which color with the sun (not like dark sunglasses) but
work normal inside. When I go outside, I hardly notice the difference with
regards to light. I'm not sure what the effect is on blue light filters etc.

I wasn't aware of a racial bias regarding hoodies (I'm what Americans call
Caucasian white, but European).

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SQueeeeeL
This seems sorta unethical, like this could very easily be biased against one
group by training data. Then if this were rolled out to a Target, they could
use this to profile people and just point to the "algorithm". Oh, the computer
says you look "shady", you can't shop here...

~~~
uoaei
Phrenology in the Cyberpunk Age

~~~
in3d
Phrenology ideas were junk but that doesn’t mean that looking at people you
learn nothing. For example, the brain size is 0.3-0.4 correlated to IQ.

~~~
tsimionescu
And since IQ is an almost meaningless measure, so is brain size!

~~~
asguy
Meaningless to whom? Do we have a better intelligence metric these days? ...
or is this satire?

~~~
tsimionescu
The fact that we don't have a good metric of intelligence doesn't make iq a
useful measure of intelligence.

IQ is only useful in determining pathologies, at the lower end, where any test
is usually helpful. For anything else, it's almost entirely snake oil.

If you want to know whether someone is good at something, the best way to test
that is to do a test for that particular thing. A test for general
inteligence, based on the assumption that general intelligence aptitude is
normally distributed in the population, is just not good for anything, and is
unlikely to be a reflection of reality, it's pure scientism (instead of
science).

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bobobooey
Lying/deceiving about what?

Also: what does "we recorded many participants performing tasks involving
deceptive walking" mean? Does this AI detect those who perform deceptive
walking, or people who are actually deceptive walking?

~~~
sampleinajar
They had participants carry a folder between two points, one contained papers
and one contained money that they were told to conceal and hand off to a
person wearing a hoodie and sunglasses. They compared the way the participant
walked.

~~~
ggggtez
You missed the key part of the experiment: They basically completely changed
the experimental setup between the two runs: The confederate changed how they
were dressed, the item was on the floor instead of on the table, and, most
importantly: they told the participant to hide what they were doing and
otherwise act sketchy!

So yeah! No surprise! They told the participant to act sketchy, and they did!
What did the participant do? They put their hands in their pocket and looked
around a bunch more than normally. Why? Because they were basically told to!
That's not "deceptive walking".

Where is the control for picking up the papers off the floor, or the money off
the table? How do we know it's not just that people will walk differently when
they are about to crouch down? Maybe that would be an interesting paper by
itself, but instead the authors think that this type of research is capable of
identifying _" deception"_ with 93% accuracy? Absurd!

There is so much wrong with the experiment, that you could write a rebuttal of
almost every decision they made.

~~~
justanotherjoe
You're not kidding. "In this procedure, the deceptive walk is induced by the
_experimenter during the briefing_ , the type of object, and the appearance of
the confederate"

This is not deceptive walking, this is honest walking. They are honestly
trying to broadcast the signal that they were told to broadcast.

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DyslexicAtheist
TLDR of this paper is here
[https://twitter.com/jackclarkSF/status/1207474543368912896](https://twitter.com/jackclarkSF/status/1207474543368912896)

~~~
notahacker
I think the 'Phrenology's back, baby' comment in the thread below captures it
quite well. Aside from the ethical implications of designing a camera that
automatically classifies people as suspicious based on their gait, what the
paper appears to actually cover is that an ML process can accurately classify
the movement differences between people walking towards a chair to pick up
some papers on it and people walking towards a chair to pick up some money
under it...

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sporkologist
I'd certainly hate to be convicted of deceptive walking. The punishment is
probably something like 5 hours of honest walking per day.

~~~
arpa
You can offset the deception classifier by 31.87% by putting in two bananas in
front pockets of your jacket. Nobody knows why.

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Jugurtha
Figure 1. illustrates the results of an LSTM that's sexually attracted to tall
muscular guys, accusing everyone else of being deceptive.

> _Deceivers put their hands in their pockets and look around more than the
> participants in the natural condition._

Doesn't it depend on _context_? If I recall correctly, one of the main
giveaways that lead to the identification of the Boston bombers was precisely
their composure during the whole situation, which investigators deemed "off"
in _that_ context and made them persons of interest.

> _Each participant was randomly assigned to walk either naturally or in a
> deceptive manner, as described below._

So it's like training a "terrorist detection" system by asking your buddies to
act "terroristy"? The experiments trains on people displaying behaviors they
think convey deception, while deception really tries to convey deceitful
behavior.

A better experiment would have been not telling the subjects about the nature
of the experiment. Then create a situation where there's a real incentive for
the subject to be deceitful. An example would be an experimenter explaining
there's a payout for the experiment. The payout must be either monetary or
something related. Like saying the study will be at some exotic location, all
accomodations taken care of, for a month, and you can bring your significant
other.

Then stopping on one answer in particular that disqualifies the subject from
the pool of people eligible to that payout.

And then explaining that the experimenter will let this slide but their
colleague will probably not; they then instruct the subject and coach them on
what they need to avoid saying on several points and before they're done
explaining, the "colleague" enters the room and starts going through the
checklist.

Now you have incentive to be deceitful and a slightly less crappy experiment
than asking people to be deceitful.

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js2
"Faster. Slower. How We Walk Depends on Who We Walk With, and Where We Live —
Men tend to walk differently with other men than with women. And Americans
walk faster with children, whereas Ugandans move more leisurely."

[https://www.nytimes.com/2018/09/19/well/move/faster-
slower-h...](https://www.nytimes.com/2018/09/19/well/move/faster-slower-how-
we-walk-depends-on-who-we-walk-with-and-where-we-live.html)

Article is a summary of this paper ("Children are not like other loads: a
cross-cultural perspective on the influence of burdens and companionship on
human walking"):

[https://peerj.com/articles/5547/](https://peerj.com/articles/5547/)

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gowld
Congratulations, your AI model can differentiate people intentionally play-
acting "deceptive" from people intentionally play-acting "non-deceptive"

After a few years of convtroversry about the low repeatability low-N
psychology research published peer-reviewed journals, now we're sharing and
upboting non-peer-reviewed non-published psychology papers?

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mc32
I can’t believe something like this would be effective against say
pickpockets: people for whom an illicit activity has become commonplace in
their lives and become natural.

~~~
bryanrasmussen
pickpockets do have extremely regular patterns however, I could definitely
believe an AI identifying potential pickpocket groups.

------
Jamwinner
Aka, kenematic phrenology. Cmon hn. We are better than this.

~~~
sli
That's probably why the comments are highly critical and not supportive of
this idea.

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mcculley
I grew up on boats and docks. I noticed as a kid that dogs on boats could
differentiate people walking on a dock without seeing them. The dogs would
become alert and start barking when they heard someone who wasn't normally
there. I still wonder if they detect known gaits or the gait of someone who is
not walking with a purpose.

~~~
jrowley
They almost certainly used their sense of smell to detect unknown people as
well.

~~~
mcculley
I agree, but I was struck by how a dog and I would detect a person at the same
time, hearing them walk along the dock. The dog could tell if the person
should be there. I could not. Because the dog perked up at the same time as I
heard the footsteps, I assumed it was the sound that the dog was using.

~~~
Spooky23
The other thing with dogs is that they are empathic and attuned to you.
Sometimes they are reacting to what you are communicating to them, before you
are even conscious of it.

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joe_the_user
Of course, they didn't go on to generate "deceptive walking" in the wild. They
generate video or pictures as deceptive or non-deceptive and they are able to
distinguish the generated stuff without labels once they'd trained a network
with labeled data.

This might (or might not) serve to prove that these deceptive gestures do
exist. The problem of even this is are that there may be a zillion cue
characteristic of the subjects being given their directions.

But even if such gestures exist, it seems pretty given that this would be
overwhelmed the complexity of images captured in the wild, where many other
variable govern behavior.

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lubesGordi
There's an anime called PsychoPass which explores this kind of tech applied
widely in society. It's very well done.

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Jimmc414
I am glad someone is finally tackling the problem of deceptive walking.

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moretai
Does it take into account anxiety as contributing to gait and posture?

~~~
longerthoughts
I didn't see any distinction between types of "deception" in the paper which
means it's classifying things like social anxiety and generally self-conscious
behavior as deceptive. While strictly true it makes the algorithm useless for
detecting security threats at this stage.

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ggm
Made me think of the whole _labrador dogs cannot hide guilt_ thing, which is
hugely anthropomorphic but it feels like it should be true: if they learned
how to model positive and negative human emotion to communicate with us for
their advantage, they probably learned shame as well.

Reddit is awash with videos of Labby dogs doing a really bad job of saying "I
didn't do it" or of dobbing in the innocent puppy, or whatever.

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blt
Can't wait for this to become the next polygraph: not admissible as evidence,
but extremely useful for coercion and extracting false confessions!

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yalogin
Aren't these kind of ideas applicable only until they are identified? Once
this become common knowledge it will just adapt.

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knolax
Somebody needs to burn down the soft "sciences" and start over. As the other
commentors pointed out this a mockery of empiricism and will do real harm when
it gets parroted by law enforcement world-wide.

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the_snooze
Is this actually either under review or a forthcoming paper somewhere
reputable?

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anigbrowl
While I could point out several questionable aspects of their methodology, I'm
even more troubled by the complete absence of the word 'ethics' from this
paper.

Do the people working on these projects never reflect on the ridiculously
broad scope of the capabilities they're claiming, the multitude of
possibilities for false or inappropriate positives (eg people who are trying
to conceal their emotional states, but for wholly valid reasons), the abuses
that will be committed by over reliance on such technology and rationalized
with spurious claims of objectivity, and the overall rush to make public
spaces and the world at large into a giant prison camp where techno-
utilitarians pass judgement on the rest of the human race?

Almost every paragraph I look at in this paper makes me roll my eyes. A small
sample:

 _We recruited 88 participants (51 female, 30 male, 7 preferred not to say,
age = 20.35) from a university campus._

Wow, fantastically diverse sample.

 _In the deceptive condition, the participant is supposed to conceal their
activities from these “onlookers.” The experimenter stresses that [an
experimental prop] is a secret, and because of the amount of money involved,
it is really important that the participant keeps anyone from noticing as he
/she does these things [with the prop]. In the natural condition, the
confederate is wearing a hoodie with the hood pulled down. However, in the
deceptive condition, the confederate is wearing the same hoodie with the hood
pulled up while wearing sunglasses. Because of this setting, the participant
makes a deliberate attempt to conceal his/her activities, resulting in
deceptive behavior_

 _We use these findings and consider the following set of gestures:{Hands In
Pockets, Looking Around, Touching Face, Touching Shirt /Jackets, Touching
Hair, Hands Folded, Looking at Phone}. We chose this set because it includes
all the hand gestures observed in the walking videos of participants, and
these gestures have been reported to be related to deception_

 _Figure 7. Gesture Features: We present the percentage of videos in which the
gestures were observed for both deceptive and natural walks. We observe that
deceivers put their hands in their pockets and look around more than
participants in the natural condition._

So you got a recruited a bunch of college students and then told some of them
to be super-covert while dealing with someone dressed up to look like a
stereotype of a shady person, but somehow you imagine this will give an
'honestly deceptive' result that accurately reflects the behavior of deceptive
people, rather than the awkward-embarrassed parody of deceptive behavior from
someone who feels they're playing a silly game.

Besides all the ethical pitfalls, their research is bad. It's like trying to
predict crime based on the observed behavior of people in a school drama class
putting on a play about cops and robbers. This is why we have so much of a
problem with junk forensic science.

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cowpig
What exactly is "deceptive walking"? I've never heard this phrase before
reading it in the abstract

~~~
rypskar
It is probably defined by The ministry of the silly walks

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zamadatix
Seems like the perfect kind of content for one of those 2 Minute Papers
videos.

~~~
DyslexicAtheist
see the twotter thread shared below.

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layoutIfNeeded
I wonder what this AI would say about Kevin Spacey in The Usual Suspects...

~~~
reidjs
Once he starts dragging his foot I assume he’d fall into the deceptive
category

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the-peter
"Keyser Söze detected with 98% confidence"

