To achieve a goal, the people working toward it must possess a suitable,
flexible repertoire. They must be able to engage in whatever behaviors
are necessary to obtain that goal – despite changing circumstances and
environmental disturbances. In some cases, this will involve carrying
out a routine that has been specified in advance by someone else. In
other cases, it will require figuring out — on the spot — an appropriate
course of action. In many situations, the end to be achieved will remain
constant but the conditions under which it is to attained will vary
.