Touch Walls


When exploring the complex, David espies a few cuneiform-like characters high up on a stone wall. He is able to climb a ladder, decipher the language quickly, ascertain that it is an interface rather than an inscription, and figure out how to surreptitiously operate it. To do so, he puts his finger at the top of one of the grooves and drags downward. The groove illuminates briefly in response, and then fades. He does this to another groove, then presses a dot, and presses another dot not near the first one at all. Finally he presses a horizontal triangle firmly, which after a beat plays a 1:1 scale glowing-pollen volumetric projection.

The material and feedback of this interaction are lovely. The grooves provide a nice, tactile, physical affordance for the gesture. A groove is for dragging. A dot or a shape is for pressing. But I cannot imagine what kind of affordances are available to this language such that David can suss out the order of operation on two undifferentiated grooves. Of course presuming that the meaning of the dot and triangle are somehow self-evident to speakers of Architect, David has a 50% chance of getting the order of the grooves right. So we might be able to cut this scene some slack.


But a few scenes later, this is stretched beyond credulity. When David encounters a similarly high-up interface, he is able to ascertain on sight that chording—pressing two controls at once—is possible and necessary for operation. For this interface, he presses and drags 14 different chords flawlessly to open the ancient alien door. This is a much longer sequence involving an interaction that has no affordance.


Looking at the design of the command, an evaluation depends if it’s just a command or a password. If it’s just a control that means “open the door,” why would it take 14 characters’ worth of a command? Is there that much that this door can do? Otherwise a simple press-to-open seems like a more usable design.

If it’s a door security system then the 14 part input is a security password. This would be the more likely interpretation since the chamber beyond contains the deadly, deadly xenomorph liquid. With this in mind it’s a good design to have a 14-part password that includes a required interaction with no affordance. I’m no statistician, but I think the likelihood of guessing the correct password to be 14 factorial, or around 87,178,291,200 to 1. I have no idea what the odds are for guessing the correct operation of an interaction with zero affordance. We’d have to show some aliens MS-DOS to get some hard numbers, but that seems pretty damned secure. Unfortunately, it also stretches the believability of the scene way past the breaking point, to presume that David can just observe the alien login screen and guess the giant password.

3 thoughts on “Touch Walls

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