A new study by Hunter Gehlbach, Carly D. Robinson, and Angus Fletcher focuses on a specific form of confirmation bias, although the researchers don’t make the connection. They’re investigating what the authors call “the illusion of information adequacy.” This phenomenon refers to the tendency for people to assume that they have enough information to make an informed decision when they often don’t know all the relevant facts. This can lead to misunderstandings, especially in social situations involving multiple perspectives.

The study involved 1,261 participants, who were divided into different groups. Some participants were given complete information about a hypothetical situation, while others were given only half the information. It was striking that those given less information still felt they had enough knowledge to make a good decision. These participants felt just as competent as those who had received complete information, and their decisions were strongly influenced by the specific information they received.

This illustrates an important point: even when people have only partial information, they are often convinced they are right. They think that others would make the same decision as they do, even though they do not have the whole picture. This stems from a combination of naive realism and, therefore, the illusion of information adequacy. People often assume that their perspective is objective and that others know the same facts and would draw the same conclusions.

The research also shows that even when people are given the complete information afterwards, they often stick to their original judgment. This highlights how deeply ingrained this illusion can be. These findings have important implications for dealing with disagreements in everyday life. Whether in personal relationships, work decisions or social issues, the tendency to assume that we know enough can lead to misunderstandings and conflict.

One lesson from this, also relevant for pupils and students, is that we need to be more aware of what we do not know. By asking more often, “Do I have enough information?” we may be able to respond to others with more humility and understanding. At a time when polarization and misinformation are widespread, this attitude could help us work better together and avoid being too quick to judge.

Abstract of the study:

How individuals navigate perspectives and attitudes that diverge from their own affects an array of interpersonal outcomes from the health of marriages to the unfolding of international conflicts. The finesse with which people negotiate these differing perceptions depends critically upon their tacit assumptions—e.g., in the bias of naïve realism people assume that their subjective construal of a situation represents objective truth. The present study adds an important assumption to this list of biases: the illusion of information adequacy. Specifically, because individuals rarely pause to consider what information they may be missing, they assume that the cross-section of relevant information to which they are privy is sufficient to adequately understand the situation. Participants in our preregistered study (N = 1261) responded to a hypothetical scenario in which control participants received full information and treatment participants received approximately half of that same information. We found that treatment participants assumed that they possessed comparably adequate information and presumed that they were just as competent to make thoughtful decisions based on that information. Participants’ decisions were heavily influenced by which cross-section of information they received. Finally, participants believed that most other people would make a similar decision to the one they made. We discuss the implications in the context of naïve realism and other biases that implicate how people navigate differences of perspective.