The Null Device
The next thing after the study of human-computer interaction might be feline-computer interaction. Now there are iPad games and painting apps ostensibly designed specifically for cats, and hackathons to develop apps for cats, and now, on the first of April, HCI guru Jakob Nielsen has published a study into Essential Design Principles for Felines. The study found that Fitts' Law holds for cats as it does for humans, but that apps for cats require larger tap targets, should respond to swiping and use blinking and animation copiously, and should have a pause mode triggered by the user lying on the tablet. Unsurprisingly, the game Fruit Ninja performed fairly well with feline users.
While it is possible to write apps for existing tablets optimised for feline users, I suspect that human-oriented tablet hardware may be somewhat suboptimal for them. Certainly sound systems designed for humans (whose hearing range extends to barely above 20kHz when young, and deteriorates with age) would sound muffled to an animal whose hearing range goes well into the ultrasonic (apparently up to 75kHz). Designing a screen for a cat's eyes would probably result in a very different device than one for humans (though, since humans have to develop and debug them, there would have to be some overlap). Needless to say, scratchproofing would also be a consideration. Also, it remains to be determined whether there is any way of allowing a cat to select different apps (or different activities) from a device, or indeed whether a non-tool-using animal such as a cat could conceive of a tablet as being anything other than a random phenomenon it reacts to.