Add arousing pre-task

[DominiqueMakowski]

Some people do a brief arithmetic task before the RS to try to "normalize" the level of arousal / state of mind.

Could be a good idea to add some optional task that:

• is arousing, i.e., requires you to mentally wake up
• is sensitive: could provide some crude measure of "attentional focus", which could be an objective measure/check of engagement/sleepiness

I am thinking either some of the analytical test with like little problems that they have to answer yes/no (the ones that we might use in PROOF) or like a brief flanker.