Knowing biases does not make one immune: the bias blind spot

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Every time one discusses and communicates with another person, there is the tendency to think that the counterpart shares the same thoughts, considerations, beliefs on the world and anything that characterizes it as ours. But, when a divergence about some subject arises, one thinks that the other came to that conclusion because they were influenced by a distorted, subjective perception, while their own vision is considered as “the reality”, pure and objective.

Thus, there is the belief that others are much more influenced by biases and heuristics than us, while in actuality we are subjected to them in the same way. This happens even when a certain bias and how it influences our decisions is explained to us. This phenomenon is called blind spot bias, one of the many cognitive errors that are part of the group of biases defined as “self-serving”.

The average American

A team of researchers from Stanford University conducted a series of surveys, aiming at analyzing the entity of this effect in people. In a first study, 24 students completed a questionnaire as an assignment for a psychology class.

Inside the questionnaire, there was the description of eight different biases, called with a neutral term such as “effect” or “tendency”, to avoid attributing negative characteristics to the phenomenon. Then, they were asked to evaluate, on a scale from 1 to 9, how much this bias influenced the average American and themselves.

The average score for the influence on themselves was 5.31, while the average American scored 6.75, thus significantly considered as more subjected to the various biases presented. In the questionnaire, there was also a question that asked to compare one parent to the average American. Curiously (or maybe not), even the parent was considered as less influenced by these cognitive errors when compared to the average American.

Later studies confirmed this effect even with respect to other social classes, such as, for example, their own fellow classmates. Even in this case, others were considered as more subjected than themselves, although at a lesser extent (5.85 vs. 5.05).

“I am better than others”

In the following study, the researchers wanted to investigate if the blind spot bias was mitigated by the knowledge of another important self-serving bias: the “better-than-average” effect, in other words the tendency to consider oneself as better than others.

In this experiment, 91 students had to evaluate themselves on six characteristics, three positive dimensions (dependability, objectivity, and consideration for others) and three negative dimensions (snobbery, deceptiveness, and selfishness). After the self-evaluation, the participants would have read the description of the “better-than-average” effect:

«Studies have shown that on the whole, people show a “better than average” effect when assessing themselves relative to other members within their group. That is, 70-80% of individuals consistently rate themselves “better than average” on qualities that they perceive as positive, and conversely, evaluate themselves as having “less than average” amounts of characteristics they believe are negative».

Everytime one communicates with another person there is the tendency to think that the counterpart shares the same beliefs.

Following this description, the participants were then asked if their first evaluation was objective or not, with a multiple-choice question. The three possible answers were:

  1. The objective measures would rate me lower on positive characteristics and higher on negative characteristics than I rated myself.
  2. The objective measures would rate me neither more positively nor more negatively than I rated myself.
  3. The objective measures would rate me higher on positive characteristics and lower on negative characteristics than I rated myself.

The first answer corresponded to the recognition of the bias, while the second one claimed objectivity in their self-evaluation. At last, the third one claimed modesty in self-evaluation.

On average, participants claimed to possess more positive characteristics (6.44) and less negative characteristics (3.64) than the average student, which scored 5 on both. In addition, 87% showed a score for all the six dimensions that corresponded to the “better-than-average” effect.

After the presentation of this phenomenon, only 24% claimed they were influenced by this bias. In fact, 63% considered their evaluations as objective. 13% even thought they had been too modest!

These results suggest that, even after presenting this bias in their decision, having learned of its existence was insufficient to make them aware of the fact that they were influenced as much as others.

According to previous research, our belief of perception of reality without distortions derives from the fact that we don’t have access to the cognitive and motivational processes that influence our perceptions. Researchers suggest that, since we cannot access these processes, we cannot have direct and conscious experience of the effects of the biases that influence us.

In a perfect world, the researchers add, people would reach a higher awareness of their own biases, acknowledging the fact that they are influenced in the same way as others. But, living in an imperfect world, they should at least make the effort to think that the counterpart is as sincere and honest as them in expressing their positions and feelings, although they could be influenced by their experiences and anything that surrounds them.

In the business world, in case a conflict arises, it is advisable to ask for a third-party opinion, but not to offer a uniquely objective point of view, which would be rejected by both parties. The third party in fact has to help in finding a common ground on which to co-plan a solution that brings benefits to both.

Carlo Sordini


  1. Personality and Social Psychology Bulletin, 28(3), 369–381.
  2. Psychological Review, 84(3), 231–259.

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