Session instrument
Task chronometry
Tempo
Measures: How long the decision took, and, above all, how that time grows
It is the only one of these methods that tests a law directly, instead of illustrating it. If someone argues that splitting the menu into two steps improves the decision, the prediction of the William Edmund HickMeasured decision time as a function of the number of alternatives, and found the logarithmic relation that bears his name.One reference in this work:1952On the rate of gain of informationSee on Wikipedia ↗See in the bibliography →–HymanRefined Hick’s measurement the following year, which is why the law carries both names.One reference in this work:1953Stimulus information as a determinant of reaction timeSee in the bibliography → law can be checked in an afternoon.
The two most cited laws on this site were born of a stopwatch, not a scanner. Hick and Hyman measured reaction time against the number of alternatives; Paul Morris FittsMeasured, in 1954, the time to point at a target as a function of its distance and size. Young, right-handed, in a laboratory.One reference in this work:1954The information capacity of the human motor system in controlling the amplitude of movementSee on Wikipedia ↗See in the bibliography → measured pointing time against the distance and size of the target. Neither of them needed to see a brain. That means their predictions are reproducible with the instrument you already have: a prototype capable of logging timestamps. Chronometry turns opinion into measurement, and it has the rare virtue of being able to fail: if the curve does not appear in your context, the law was not holding there, and that is also a result.
How to run itRecord the interval between the screen appearing and the action happening, with at least twenty repetitions per condition. What matters is not the absolute value: it is the curve, when you vary the number of options or the distance to the target.
SeesIt tests a theoretical prediction with the prototype that already exists, and accepts being proved wrong.
Does not seeTime does not distinguish cause: hesitating out of doubt and hesitating out of distraction give the same number.