Eye Tracking and Acceleration

How do our eyes scan across a landscape? Contrary to popular belief, they don't scan smoothly across a scene, they observe a series of images. The eye is capable of panning smoothly however. If something moves in your field of view, your eyes track it smoothly. This has an important effect on our perception of motion. It makes it more difficult to see when objects are accelerating since the eye tracks all motion quite smoothly.

Category:

Education

Tags:

• science literacy
• acceleration
• eye tracking
• eye pan
• evolution of sight
• perception
• motion
• falling object

[jamesahibbard]

I have a question, does the angle at which we view the ball (ie we watch it drop from eyelevel, rather than drop past eye level have any effect on our perception of the speed of the ball. (ie the further down it is, the less the angle off the horizontal (Angle of depression? There is a correct term that I can't think of) changes, in terms of distance dropped, possibly balancing out (to some degree) the change in speed.

[1veritasium]

@jamesahibbard This is a good point - but I've tried it with people at many different angles, close up and far away and they still see it as moving with constant velocity. Therefore I think the perception is more a result of our smooth tracking eyes.

[thebottlemusician]

I have a question. Is there a positive side to this. In like a biological standpoint. Would this mentally slow down predator to us giving us more time to react? Or is this just a simple fact to counter misconception.

[1veritasium]

@thebottlemusician yes there is a positive side - we track smoothly those things that are moving, which makes us well coordinated and able to track prey and avoid predators. It just has the funny side effect of obscuring the laws of physics.

[harokkorah]

it accelerates at 9.81m/s² down

[MrShanehaider]

booobs

[fcoalvaradov]

in Medicine this movements are called fixation (the focusing on an object) and saccadic movement (the fast movement of the eyes from one image to the next one you're trying to see)... what happens is this: on the landscape you see one house, then another then another then the beach.. your eyes will jump from one place to another... following something we will fixate that focusing on that movement thus, a smooth movement, try the following: see a tree while driving a car, then back to the road ;)

[fcoalvaradov]

well let me ask something... If we stare at someone who is walking (constant velocity) and then he starts running (accelerating) we can notice that change of velocity... don't we? the ball is falling so fast and at that height you can just analyze that acceleration with a camera... common sense will say they were at the same speed

[compaq1275]

she has really pretty eyes... :)

[OliverWattsDesign]

your videos are so interesting an you are a champion, looking forward to more

[musicplayah]

I actually know why it goes from frame to frame with big skips when going over horizon also. If we didn't the environment would blend, just like the ball falling to the ground. The fact that the ball gets a little smudgy doesn't matter as much as if your whole view does.. kinda figured it out from the Vsauce on chickens and how they can't move their eyes and therefore they bob their heads back and forth with their head, let the body catch up then bob another distance.