Now that the ability to make decisions is regarded as unmeasured in IQ tests, one might ask what the ability comprises.
In it's simplest form the making of a decision based on what we call thought as compared with instinct requires anticipation of a future event. One wonders where thought begins and instinct ends. Also, might one include intuition as a contributor to thought, as something standing on it's own right, or as an aspect of instinct.
In any event, thought may not be conscious, but a product of drill, practice, brain washing or propaganda, feelings translated into words on which decisions are based.
Thinking is normally considered to be a verbal activity, but as we know any of the senses might be involved and some of the senses bypassed. Decisions might thus arise before verbal reasoning, as would occur in many athletic activities, in art, creativity, symbolic reasoning.
How a decision making entity arrives at a decision is obviously varied. At some point, however, sufficient energy is released to make a decision have effect in action. Decision taking is thus a different stage of activity when compared with considering.
All decisions are a result of a trigger and once the trigger is activated a result representing a choice occurs. One aspect of this is to consider whether decisions arise from triggers that are sufficiently well understood. We make many choices, and often very quickly. How effectively we arrive at a choice that requires no correction is critical in evaluating decision making ability.
Obviously, many people will make decisions thinking that they can revise them later on based on a variety of criteria. The ability to move along the decision taking course of actions will also vary from person to person. Some will make few revisions and fast decisions while others will make many revisions and innumerable choices to refine decisions further and further over time.
Thus, it is not simple to measure decision taking abilities as these may themselves be a matter if style, which again may be a matter of intelligence, memory abilities, visualization, patience, breadth of consideration, and so on. Gets pretty complex doesn't it. That should teach us how divided seemingly simple processes can become, and even Occam's Razor may need a prior Razor!