have you ever considered how your eye
scans across a landscape I think most
people assume that like a video camera
it pans smoothly across the scene but I
don't actually think that's what happens
in truth I think the eye jumps from
image to image as it moves across this
scene so I'm going to try to find a
volunteer to help me demonstrate that
what I'd like you to do is scan across
this landscape as smoothly as you can
you try that
tell me about the process of scanning
across you know from the point it just
feels like you're stopping and go and
like stop in and go in and yeah it's
feels like like there's a pause all the
time constantly when you're going across
it's not like you're just looking
straight across yeah it's not smooth the
eye is capable of tracking smoothly
however if something moves across your
field of view your eye can lock on to it
and move smoothly with it
what I like to do is I'd like to repeat
that little game but I would like to ask
you just to walk across on those rocks
and then I'd like you to just like
follow her along with your eyes except
possible yeah okay let's give it a shot
you wanna go over there okay
all right go yeah go for it can I just
get your reaction on on what that was
like
how was that the sound were different I
felt a lot smoother because I was
following something sort of just looking
at something yeah I don't know just like
if you follow something you're just your
brain focuses on that one thing and you
just kind of just go with it why would
that be useful to be able to pan with a
moving object how does that affect our
perception of motion well I think it
makes most motion seem quite smooth and
makes it more difficult for us to
determine when things are accelerating
one last question since I've got you
guys here so what I want to do is I want
to drop the ball I want you guys to
watch it and then tell me how the ball
moved is that fair enough watch it till
hits the ground and then afterwards
you're gonna tell me how to move okay
three two one okay I'll do it just one
more three two one
could you tell me about the motion of
the ball what was it doing as it went
down it's fast I don't know it just
seemed like it just dropped but it
wasn't even moving
you just seen the ball drop the ball not
was it you didn't see it like here you
just saw it from there to there would
you say its speed was constant or do you
think its speed was changing constant
yeah it was the same yeah the whole way
down yeah no acceleration the goal of my
whole experiment today I'll let you guys
in on the secret is to point out that
the eye tracks motion very smoothly so
when the ball light goes down is really
easy for us to track that yeah and it
looks like it's just doing one constant
thing but in fact it is speeding up the
whole time when I release it it's not
moving at all and when it hits the
ground it's actually going quite fast so
that was kind of my point if you scan
across like a stationary scene then your
eyes doing this weird jumpy thing yeah
but then if you're actually moving with
an object or with a person or something
then your eyes are so smooth you don't
even notice yeah yeah but something
that's telling you have to me that's
when it starts to jump but if it's
something moving your eyes and follow
that it's much easier yeah excellent