Why do we cut short our decision-making process?

This 2014 Zurich study found that people adapt their goal-directed decision-making processes in certain ways.

First, the researchers found that the subjects usually acted as though the computational cost of evaluating all outcomes became too high once the process expanded to three or more levels. Their approach to a goal involved developing subgoals. For example, for a three-level goal:

“Level 3 was most frequently decomposed into a tree of depth 2 followed by a depth-1 tree.”

A level 3 tree had 24 potential outcomes (24 outcomes = 3*2x2x2) whereas a level 2 tree followed by a level 1 tree had 10 potential outcomes (10 outcomes = 2*2×2 + 1*2).

Second, the subjects memorized and reused subgoals after their initial formation. The researchers found that this practice didn’t produce results significantly different than the optimal solutions, but that could have been due to the study’s particular design. The design also ensured that the subjects’ use of subgoals wasn’t influenced by rewards.


“It is known that nonhuman primate choices, for instance, depend substantially on their own past choices, above and beyond the rewards associated with the decisions. Similar arguments have been made for human choices in a variety of tasks and settings and have been argued to be under dopaminergic and serotonergic control.”

Third, ALL 37 subjects were unwilling to evaluate decisions that had initial large losses, even if they could see that the path to reach the optimal solution went through this loss outcome! The researchers termed this behavior “pruning” and stated:

“Pruning is a Pavlovian and reflexive response to aversive outcomes.”

The lead author relied on a previous study he coauthored to elaborate on the third finding. One statement in the previous study was:

“This theory predicts excessive pruning to occur in subjects at risk for depression, and reduced pruning to occur during a depressive episode.”

The current study’s subjects were screened out for depressive conditions, though. They were somewhat conditioned by the study design, but not to the extent where their behavior could be characterized as Pavlovian responses.

Fourth, the subjects’ use of larger subgoals wasn’t correlated to their verbal IQ.

So, what can we make of this research?

  1. Are shortcuts to our decision processes strictly a cerebral exercise per the first and second findings?
  2. Do we recycle our decision shortcuts like our primate relatives, uninfluenced by current rewards?
  3. Or is it rewarding to just not fully evaluate all of our alternatives?
  4. Do all of us always back away from decisions involving an initial painful loss, even when we may see the possibility of gaining a better outcome by persevering through the loss?
  5. Is it true that we excessively cut decision processes too short – such that many of our decisions are suboptimal – when we’re on our way to becoming depressed?
  6. Are we overwhelmed when depressed such that we don’t summon up the effort to cut short or otherwise evaluate decisional input?

Let me know your point of view.

http://www.pnas.org/content/112/10/3098.full “Interplay of approximate planning strategies”

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