I found a blog post "Is postdecisional dissonance functional?" that takes exception to calling "Post-decision dissonance" irrational (post-decisional dissonance is where the self-judged value of a chosen item increases, and the value of a declined item decreases, compared to the self-judged values before the choice is made: http://en.wikipedia.org/wiki/Cognitive_dissonance#Post-decision_dissonance ).
"Is postdecisional dissonance functional?" seems like a yes/no question, but the answer can change from situation to situation. We can construct a situation where this bias is "Irrational/dysfunctional", or is "Rational/functional".
Example: If postdecisional dissonance is the way that one "stops" the decision process, instead of endlessly revisiting a decision and wasting time and energy, then postdecisional dissonance is functional (this is the point raised by Konrad Talmont-Kaminski). If postdecisional dissonance keeps you from switching decisions when later you are offered the alternate choice along with a small but real payment, because you deny yourself the additional payment even though the options were judged to be identical in value, postdecisional dissonance is dysfunctional.
Which is the most likely scenario? What is the cost of a more rigorous and rational analysis? Different answers from subtle changes to these questions...
All of these biases, because they are manifest in humans today, cannot absolutely prevent reproductive success or success in cultural transmission of ideas, obviously. So you are on very shaky ground calling these biases non-adaptive. And if you cannot call them non-adaptive, what is the exact basis for calling them "Irrational/dysfunctional"?
Modeling, instead of using the language of Bias and Rationality and Functionality
|George Mason University,|
Dept of Statistics,
Gallery of Great Statisticians,
George E. P. Box
(1) the failure mode of decision that you are trying to avoid and
(2) how you are modeling the
(2A) cost of falling victim the failure mode and the
(2B) cost of remedy
(3) how you are modeling the likelihood of different scenarios taking place.
And different models will give different answers. As George E. P. Box says "All models are false but some models are useful."
Very helpful reply [ http://deisidaimon.wordpress.com/2010/07/25/is-postdecisional-dissonance-functional/#comment-1675] from academic Konrad Talmont-Kaminski, but my profound ignorance prevents me from getting much from it. I am self-taught exclusively from an engineer's perspective of decision making from Decision Analysis texts [ term coined in 1964 by Ronald A. Howard ].
I fixed the post above, to add
1) specific examples as to how postdecisional dissonance can be functional or dysfunctional,
2) why one is unjustified to call manifest biases non-adaptive, and
3) the need to model the likelihood of different situations arising, or else the the analysis is nonsensical.
[Edit #2 7/29/2010]
Konrad Talmont-Kaminski recommends the writings of Herbert Simon, Nobel Prize winner in Economics 1978.