Lack of information doesn’t discourage confident decisions

Like it or not, it's near impossible to have every piece of information about a given situation, whether that's something that's going on at work, a news event, or a relationship. Yet we're not always great at acknowledging that – not knowing what we don't know, as Socrates put it. There's even a theory, the Dunning-Kruger Effect, addressing our lack of self-awareness in this area, suggesting that people with particularly limited knowledge of a subject are likely to vastly overestimate their abilities.

In a new study, a team looks at what happens when we believe we have adequate information when making a decision. They find that people tend to assume they have the same amount of information as everyone else — making them feel they're just as competent as anyone to make thoughtful, sensible decisions that everyone will agree with.

Firstly, the 1,261 participants were given a passage to read, describing a school based in an area where a local source of water was drying up. Because of this, the school had to make a decision: either stay put and hope for more rain, or merge with another school in an area with more water.

However, different groups of participants saw different arguments. The control group saw an article outlining seven features of the situation, including the benefits of merging, the benefits of staying put, and a more neutral statement. The pro-merge group only saw arguments describing the benefits of merging, and the pro-separation group saw only arguments about the benefits of remaining as is.

They then indicated whether they felt they had enough information to make a decision about what the school should do and if they felt they were able to make a competent decision, before deciding whether they thought the schools should merge or not. Participants also indicated whether they felt others would make the same decision as them, if they felt they understood the key details of the situation, and how curious they would be to read more about the situation.

After answering these questions, half of participants read a second article outlining the remaining arguments, which they hadn't yet seen. They then had the opportunity to update their recommendation on what the school should do.

Even though the pro-merge and pro-separation groups received half the information that the control group did, they felt as if they had enough information to make a decision, and that they were competent enough to do so. Participants in all groups also felt that most people would agree with their decision, regardless of how much information they'd seen (62% in the control group, 68% in the pro-merge group, and 65% in the pro-separation group).

There were similarly high levels when it came to confidence in their decision: again, although they only had half of the information available to them, those in the pro-merge and pro-separation groups were confident about their final decisions. In these groups, 71% endorsed their final decisions even after receiving further information, as opposed to 65% in the control group.
This all suggests that people generally believe the information they have is enough to allow them to make good decisions, and that others would agree with them given the same info — even when that simply isn't true.

Though the team had hypothesised that participants would change their recommendations after reading additional information, this actually wasn't the case — 64% of participants in the pro-merge group stuck with their original recommendation even after seeing extra arguments, and 68% in the pro-separation group. The overall final recommendations from those groups, though, were "indistinguishable" from the control group, which the team argues is evidence for the fact people are open to changing their mind when given new information.

While the topic of merging hypothetical schools was intentionally uncontentious, it's possible that these findings may not extend to many pressing debates in the real world as a result. Future research could focus on information adequacy when it comes to topics people already feel passionately about, or on those people already know a fair amount about.

As for the practical ramifications of the study, the team argues that the results underline the need for humility. "Although people may not know what they do not know," they write, "perhaps there is wisdom in assuming that some relevant information is missing." Assuming that we don't know everything and staying curious about gaps in our knowledge may result in smoother, more informed decision making processes for all.

Read the paper in full:
Gehlbach, H., Robinson, C. D., & Fletcher, A. (2024). The illusion of information adequacy. PLOS ONE, 19(10), e0310216. https://doi.org/10.1371/journal.pone.0310216

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