The capability field is a match: skill held up against what the task demands. If the demands sit far above,
it is experienced as overload. If they sit far below, engagement falls. In between lies what
Csikszentmihalyi called flow. That is why the curve is an inverted U — both too little and too much cost something.
It is the best evidenced of the four fields. Brain imaging has shown boredom, flow
and overload as three distinct states in the same experiment, and learning research finds
the same pattern.
It holds for rule-following too. Too few frames leave people unsure what is expected;
too many competing rules make adherence fall. We measured it on our own service:
with 56 rules in play at once, average adherence fell to 33 %. The right amount lies in between — and it can be measured.