viés
Choice-supportive bias
After making a decision, people tend to remember the positive aspects of the chosen option and to forget or play down the negative ones.
Confirm the choice, but leave the way back open.
After choosing, memory works in favour of the choice. The oldest relative of this dates from 1956, when Jack BrehmOne reference in this work:1956Postdecision changes in the desirability of alternativesSee in the bibliography → showed that, minutes after deciding between two similar options, people start rating the chosen one better and the discarded one worse. That was a change of preference, not of memory, and his method took a heavy critique in 2010, because it produces the same result even when no preference changes at all. What this page deals with is the next step, measured in memory by MatherMeasured how memory distorts in favour of the chosen option, attributing to it qualities that belonged to the other.One reference in this work:2000Choice-supportive source monitoringSee in the bibliography → and Johnson in 2000. Nothing changes in the two options, only the fact that one of them has become yours, and from there the person grows more comfortable with the decision and a worse judge of it at the same time, without noticing either.
What the brain does with it
The biological mechanism behind the effect, and how much of it was actually measured.
After deciding, the person remembers the chosen option as having more qualities and the rejected one as having more flaws than either of them had at the moment of choice. It is a memory distortion in favour of the decision already made, measured by comparing the judgement before and after. Remembering is reconstructing, and the reconstruction depends on the hippocampusThe structure that turns recent experience into lasting memory. Everything your interface asks the person to remember tomorrow passes through it today.See it in Memory →See in the glossary → and on the prefrontal cortexThe region behind the forehead, where the person decides, plans and sustains attention. It keeps one thing in focus at a time and inhibits the rest: it is where the bottleneck of conscious decision usually tightens.See it in Memory →See in the glossary →, which judges where each piece of what came back came from, as MitchellOne reference in this work:2009Source monitoring 15 years later: what have we learned from fMRI about the neural mechanis…See in the bibliography → and Johnson reviewed in 2009. Those structures were measured in memory tasks, not in this bias, and the link is mine.
The body this law presumes
Who it was measured on, and what changes when the body on the other side is another.
The mechanism is cognitive and asks for no specific sense or repertoire, which would make it a good candidate to cross any body. Except that the source of the statement is precisely a study about age. Mather and Johnson measured older adults aged 64 to 83 and young adults aged 18 to 22, and the bias came out stronger in the older ones, even with the two groups matched on memory accuracy. The review by LindReviewed the choice-supportive bias and separated four forms of it, only one has solid support, which narrows the law considerably.One reference in this work:2017Choice-supportive misremembering: a new taxonomy and reviewSee in the bibliography → and colleagues narrows the rest by separating what is measured. Of the four forms of the bias, one has solid support: the memory that attributes to the chosen option a quality that actually belonged to the other. The other three, distorting the fact, inventing the memory and forgetting what is unfavourable, have much weaker support, and there is a study that found the effect in no age group at all.
How design translates it
What to do with it on a screen, without turning a finding into a rule.
How to measure this in your product
After the decision, a visual reinforcement, a positive confirmation and a welcoming message consolidate satisfaction and reduce retroactive doubt. The “order confirmed” screen that shows what was chosen, and not just a reference number, does that job. And, since the bias also makes the person a worse judge of their own choice, the way back stays open and visible, with swap and cancel to hand, without that looking like a mistake on their part.
Onde vira manipulação
The same lever, pointed at the person on the other side.
Validating decisions already made without leaving room for reappraisal. The ethical practice is the opposite: offering alternatives and making reviews and reversals easy.
Where it breaks
Where the law does not hold, holds less, or holds in reverse.
Of the four forms of the bias, only one has solid support, and that narrows quite a lot what can be claimed. The person remembers what they chose better, and from there to concluding that they rewrite memory in favour of the choice is another matter. The practical caution is straightforward. If your product asks the user whether they liked the decision they made there, you are measuring the bias, not the decision.
Um caso
A real product where this showed up, with what happened and where to check it.
The cancellation screen that lists what you lose
A month after choosing a plan, almost nobody remembers the reservations they weighed when choosing. Memory reconstructs the decision already cleared of the objections. The cancellation screen that lists everything you are about to lose works on top of that: it reactivates the good side, which memory preserved, against a present annoyance that it did not keep. The honest way round is not to remove the list, it is to balance it. Show also what the person stops paying, keep the cancel button at the same visual weight as the stay button and leave the way back open afterwards. Whoever cancels and is treated well comes back; whoever cancels and has to fight does not.
Experimente
A piece to check in your own body what the text has just claimed.
What you remember about the plan you chose
Choose one of the two plans. After a short distraction, tick which caveats belonged to the plan you chose.
Before going on, a quick count: how many filled circles are there?
Which of these caveats belonged to the plan you chose?
Choose a plan.
After the choice, memory keeps the good side of what we chose and the bad side of what we rejected. That is what the cancellation screen listing everything you will lose leans on. Here the distraction lasted seconds; in real life it lasts a month, and the bias grows in that interval.
Neighbouring concepts
Structures linked by a bridge of my own
Sibling concepts
Fontes
Enunciado citado de Mather; Johnson, 2000.
- MATHER, M.; JOHNSON, M. K. Choice-supportive source monitoring. Psychology and Aging, v. 15, n. 4, p. 596-606, 2000. DOI
Leitura complementar: Choice-supportive bias Wikipedia em inglês