After landing on Tau Ceti, Barbarella is captured by feral children who tie Barbarella to a set of poles and turn a set of robot dolls on her.
The dolls exhibit some crude intelligence. They walk on their own toward Barbarella. Stomoxys (or is it Glossina? It’s tough to tell with these two.) twists a knob on a control panel of four similar, unlabeled knobs, and the dolls’ piranha-toothed mouths begin to crank open and slam shut. They then attack Barbarella, clinging and biting her legs and arms.
At first the dials seem a strange choice for a killing device, but then you realize that this isn’t mean to be efficient. Rather, the choice of dials for controls fits the childrens’ awful goal. Stop dials are best for setting variables within a range of values. The dolls must have a few variables, like walking speed, biting force, and biting speed, that the horrible children will want to play with as they entertain themselves with this torture.
And of course to “improve” this interface you might want to label the dials so a new user would know what does what, but who would really want to make torture toys more usable?