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Hi! Today we’re going to be comparing the usability of various household devices (Microwave, TV remote, keyboard, etc.) against those of research devices (like eye trackers and brain-computer interfaces).
Information Transfer Rate and Bits/Min
To do this, we’ll be investigating each device’s information transfer rate (ITR), or how fast the user can communicate with the device. We have some intuitive sense of this — obviously the keyboard allows for faster and more varied input than the TV remote. It’d be easy to compare the speeds if they had the same number of buttons, but since they don’t, we have to define some common metric to measure information input speed. This will be calculated in units of bits per minute.
This metric encapsulates buttons, screens, and more, and works across devices to let us compare various interfaces. It’s calculated by taking the log of the number of possible inputs, then multiplying by how many times you can perform that input in one minute (for instance, hitting any of 8 buttons at a button per second gives you a 3*60 buttons/sec = 180 bits/min).
Inspiration
While reading about the information transfer rate of tech still in development (eye tracking, brain-computer interfaces, etc.), I wanted to see how far they were from being practical e.g. in comparison to normal devices we use today. Since most researchers will standardize their results into units of bits per minute, I…
