the IdeasBlog

Perceptual Threshold


Animation, films and television “work” exactly because we humans don’t perceive the fact that the illusion of lifelike motion can be created from a succession of quickly changing still images.

You intellectually know that a movie is just a bunch of still photos presented really fast. But what you perceptually know is that it is believably realistic. Our threshold for fooling ourselves about that experience is remarkably low.

You could engineer in more changes per second or increase the resolution of the images, but – for the most part – we just wouldn’t notice the difference. Digital images – which were laughably crude, chunky and clunky only a few years ago – now far outstrip our perceptual threshold.

In the usability game, perception is everything.

Seeing is believing. Sort of.

One of our first object lessons came with the making of computer-generated spaceflight sequences for “Star Wars”. The visually crisp imagery moved right, but didn’t look right until Industrial Light & Magic realized that they needed to smear the spaceships a little (kind of like the blurry moving image artifact you get in a still frame). Only then did we humans accept that the image was real. It’s called motion blur.

Lets’s not overlook the positive aspects of human frailty.


User Experience: It ain’t just for the InterWeb.