People show confirmation bias even about which way dots are moving

September 13, 2018, Cell Press
This visual abstract depicts findings that people show confirmation bias even about which way dots are moving. Credit: Prat-Ortega & de la Rocha, Current Biology

People have a tendency to interpret new information in a way that supports their pre-existing beliefs, a phenomenon known as confirmation bias. Once they've made a decision about which house to buy, which school to send their kids to, or which political candidate to vote for, they have a tendency to interpret new evidence such that it reassures them they've made the right call. Now, researchers reporting in Current Biology on September 13 have shown that people will do the same thing even when the decision they've made pertains to a choice that is rather less consequential: which direction a series of dots is moving and whether the average of a series of numbers is greater or less than 50.

"Confirmation biases have previously only been established in the domains of higher cognition or subjective preferences," for example in individuals' preferences for one consumer product or another, says Tobias Donner from University Medical Center Hamburg-Eppendorf (UKE), Germany. "It was rather striking for us to see that people displayed clear signs of bias when judging on sensory input that we expected to be subjectively neutral to them."

The findings by a team of researchers from UKE and Tel Aviv University, Israel, suggest that confirmation bias is linked to , a process in which people react to certain bits of information or stimuli and not others when several are presented at the same time. They also set the stage for studies to unravel the underlying brain mechanisms, the researchers say.

Although confirmation bias is well known, it hadn't been clear what drives it. Is it that people, after making a decision, become less sensitive to new information? Or do they actually filter new information so as to reduce conflict with the decision they've already made?

To explore this question, the researchers, including first authors Bharath Talluri and Anne Urai, both from UKE, asked study participants to look at two successive movies featuring a cloud of small white dots on a white computer screen. Their task was to report the direction the coherently moving dots, which was challenging because these dots were embedded in many more dots that moved about randomly. After the first movie, participants were asked to choose between two categorical options: whether the coherent motion pointed clockwise or counterclockwise from a reference line drawn next to the cloud of dots. After the second movie, they were asked to drag the mouse over the screen to indicate their best continuous estimate of the average direction across both movies they had seen.

The experiments showed that participants, after making an initial call based on the first movie, were more likely to use subsequent evidence that was consistent with their initial choice to make a final judgment the second time around. The finding suggests that the initial choice a person made in the simple visual motion task acts as a cue, selectively directing their attention toward incoming information that's in agreement.

In a second series of experiments, the researchers presented a related numerical task. At first, they were asked to judge whether a series of eight two-digit numbers averaged greater or less than 50. In a second, they were asked to provide a continuous estimate of the average between 10 and 90. Again, participants' answers showed a pattern of confirmation bias and selective attention.

The researchers say the findings help to identify the source of confirmation biases, with implications for understanding the bounds of human rationality. For those of us attempting to make informed decisions in the real world, the new study offers a reminder.

"Contrary to a common phrase, first impression does not have to be the last impression," Talluri says. "Such impressions, or choices, lead us to evaluate information in their favor. By acknowledging the fact that we selectively prioritize agreeing with our previous choices, we could attempt to actively suppress this , at least in cases of critical significance, like evaluating job candidates or making policies that impact a large section of the society."

Explore further: How people use, and lose, preexisting biases to make decisions

More information: Current Biology, Talluri and Urai et al.: "Confirmation Bias through Selective Overweighting of Choice-Consistent Evidence" www.cell.com/current-biology/f … 0960-9822(18)30982-5

Related Stories

How people use, and lose, preexisting biases to make decisions

August 16, 2018
From love and politics to health and finances, humans can sometimes make decisions that appear irrational, or dictated by an existing bias or belief. But a new study from Columbia University neuroscientists uncovers a surprisingly ...

Self-consistency influences how we make decisions

May 23, 2018
When making decisions, our perception is influenced by judgments we have made in the past as a way of remaining consistent with ourselves, suggests new research published in eLife.

Decider or ditherer? How we make decisions

April 3, 2018
Professors Peter Brown and Rafal Bogacz in the Nuffield Department of Clinical Neurosciences describe their research team's discovery that a certain 'hold your horses' function in decision-making occurs in an extremely brief ...

Video games can improve decision-making

March 11, 2016
Research on decision-making bias found that interactive training exercises using video games actually improved participants' general decision-making abilities and when used alongside other traditional training methods. The ...

Recommended for you

Use of electrical brain stimulation to foster creativity has sweeping implications

September 18, 2018
What is creativity, and can it be enhanced—safely—in a person who needs a boost of imagination? Georgetown experts debate the growing use of electrical devices that stimulate brain tissue, and conclude there is potential ...

Engineers decode conversations in brain's motor cortex

September 18, 2018
How does your brain talk with your arm? The body doesn't use English, or any other spoken language. Biomedical engineers are developing methods for decoding the conversation, by analyzing electrical patterns in the motor ...

Team identifies brain's lymphatic vessels as new avenue to treat multiple sclerosis

September 17, 2018
Lymphatic vessels that clean the brain of harmful material play a crucial role in the development and progression of multiple sclerosis, new research from the University of Virginia School of Medicine suggests. The vessels ...

Circuit found for brain's statistical inference about motion

September 17, 2018
As the eye tracks a bird flying past, the muscles that pan the eyeballs to keep the target in focus set their pace not only on the speed they see, but also on a reasonable estimate of the speed they expect from having watched ...

Mouse study reveals that activity, not rest, speeds recovery after brain injury

September 17, 2018
When recovering from a brain injury, getting back in the swing of things may be more effective than a prolonged period of rest, according to a new Columbia study in mice. These findings offer a compelling example of the brain's ...

Fine-tuned sense of smell relies on timing

September 17, 2018
If you can tell the difference between a merlot and a cabernet franc just by smell, it's probably all in the timing.

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.