Confirmation bias
People are not likely to change their point of view from what they already believe because of confirmation biasBRENDAN SMIALOWSKI/AFP/Getty Images

People tend to see and notice views that already confirm their own personal view of the world. This effect is known as confirmation bias and a new study carried out at the University Medical Center Hamburg-Eppendorf and the University of Amsterdam (UvA) has finally found the mechanism upon which it works.

Confirmation bias, according to researchers, is the tendency to filter out facts and figures that already support a preconceived notion about a subject, even if the information is new and something that was not previously known, so long as it aligns with a certain belief.

The new study has taken this one step further, notes a report by UvA, where researchers found that the bias exists not only in important matters that shape a person's view but also in rather simple cases and that people "excessively" focus only on evidence that supports past choices.

Going back to the fifth century, this bias has been well-documented but not much is known about how it works and brain activity that leads to it. As a way to understand the brain's mechanism with regards to this bias, researchers set about creating a visual experiment where participants were told to make simple decisions about how they perceive visual stimuli.

"It is commonly believed that people make their decisions not just based on the relevant evidence, but also show cognitive biases that ensure consistency between choices," says Dr Anne Urai, joint first author of the study. The study investigated whether choices actually influence the later decision process itself.

As part of the experiment, respondents were shown a video that demonstrated a cloud of dots, and were asked to choose the general direction in which the dots were moving according to them. Researchers later showed a second video and then asked the participants to actually estimate an average direction of movement between the dots.

People are more likely base future decisions on past happenings rather than look into new evidenceMax pixel via Creative Commons

They reportedly used computational modelling to find out what effect the first video had on the decision made by the participants and their final judgement.

"What we discovered was that participants were more receptive to evidence that agreed with their initial decision", says Bharath Talluri, joint first author from the University Medical Center Hamburg-Eppendorf.

This indicates that even when making a simple and emotionally neutral decision, people don't act in a way that does not put in some level of context. Instead, people are more likely to be guided by evidence, especially what is consistent with and verifies their initial decisions. "This suggests that our choices may act as cues to selectively direct attention to those pieces of incoming information that agree with them," says Talluri.

The study and its findings were first published in the journal Current Biology.