BRmovie.com: Blade Runner Souvenir Magazine - Official Collector's Edition

Syd Mead came up with the designs for the incredible Voight-Kampff machine. He had a discussion about it with Ridley and me and then came up with about three or four schemes. Finally we came down to a unit that opens up and has a breather and an oscillator and all sorts of gadgets. Basically it was a lie-detector machine. the lie is, I am not a replicant.
- LAWRENCE G. PAULL (Production Designer)

Ridley drew a sketch of this machine, which he said was an exotic kind of lie detector, and it reads the iris contraction. When you lie, or are under stress, your iris tends to contract or expand. The Voight-Kampff machine would center on the pupil and the operator would have a full-screen enlarged picture of the iris. the machine would measure the contractions of the iris and put it on a graph or something.

Ridley wanted this machine to be fairly delicate, briefcase size, easily portable, but it also had to look very dangerous sitting on a desk, very threatening, and sort of like a giant tarantula. Since it isn't dangerous because it's large, it had to be dangerous because it's threatening. So we decided it should breathe. My rationale for that was that the machine would draw in air samples in the immediate area. when you are scared or apprehensive, your body gives off an odor. and I think it's minute molecular detachments of protein or something that your sweat glands give out. So your chemistry changes when you're tense. You unfold the machine and it starts itself as soon as the subject walks in the room; this arm moves around and focuses at the supect's eye. It's sort of alive in a way all by itself, and it's very, very threatening.
- SYD MEAD (Visual Futurist)