In the experiment by Peterson and Peterson that demonstrated the decay of short-term memory over 20 seconds, why did they ask their subjects to count backward by threes during the delay?

Question

Quizplus · Accepted Answer

The reason why the subjects were asked to count backward by threes during the delay was to prevent rehearsal of the information and thus demonstrate the decay of short-term memory. Rehearsal is a process that can extend the duration of short-term memory, so by engaging the subjects in a distracting task, the researchers aimed to prevent them from rehearsing the information and facilitate memory decay.

In the Experiment by Peterson and Peterson That Demonstrated the Decay