Chapter 24 The value of reaction times and error rates in psychology
Any neuronal activity in our brains takes time. And more complicated things take more time! Which is great for us as psychologists as this gives us the opportunity to understand how our mind works by studying reaction times and error rates!
Thus, adding something extra to a task typically slows us down (and increases our error rates). Let’s take a look at what is perhaps the simplest example of this idea: The comparison of simple and choice reaction time. In fact, this idea was introduced more than 150 years ago in one of the most influential publications in the history of psychology:
The idea occurred to me to interpose into the process of the physiological time [i.e., simple reaction time, J.D.] some new components of mental action. If I investigated how much this would lengthen the physiological time, this would, I judged, reveal the time required for the interposed term.
F. C. Donders (1869), On the speed of mental processes
Simple reaction time task
Try out a simple reaction time task. There are 24 trials overall. Once finished, you will be presented with your mean RT for this task.
Click here to run the simple reaction time task.
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Choice reaction time task
Try out a choice reaction time task. Again, there will be 24 trials overall. You must get at least 21 out of 24 trials correct to obtain your mean RT for this task.
Results
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Note that the cost of making a choice is typically between 100 and 300 ms. Given that raw RTs in a simple reaction time task are typically between 200 and 350 ms, this represents a substantial cost.