Study links hippocampus with unconscious bias
Brain diagram. Credit: dwp.gov.uk
(Medical Xpress)—A new US study into brain function has found links between preferences and the regions of the brain involved in connecting new memories to old ones. The associations formed provide shortcuts the subconscious can use for decision making.
The hippocampus is an area of the brain known to be one in which links between memories are formed, but until now it was not known that this brain region is involved in steering the brain towards making particular choices over others when faced with new decisions for which we have no previous experiences to draw on.
In a paper published in the journal Science, research psychologists G. Elliott Wimmer and Daphna Shohamy of Columbia University in New York report on their study, which used functional magnetic resonance imaging (fMRI) of regions of the brain. In the study, they asked 31 volunteers to complete a three-part task while in the machine. Throughout the task their brain activity was determined by the fMRI.
In the first part of the task (association) the subjects were shown paired images. One image of each pair was a circle with a colorful pattern inside, while the other was either a landscape, body part or human face. The same circle was shown with the same image each time, enabling the subjects to associate each image with the appropriate circle.
This video is not supported by your browser at this time.
Our brains are biased to make certain choices based on memories we aren’t even aware of. As illustrated here in a simple animated example, this can arise because of how the brain builds associations in memory, how these associations are automatically recollected, and finally how reward value can spread across associations. Video courtesy of G. Elliott Wimmer and Daphna ShohamyIn the second part of the task (reward) the volunteers were shown images of just the circles, and this time they were told that they would receive a reward of $1 for viewing half of the circle images. In this way the subjects were able to learn to associate some of the circle images with money.
In the third part of the task (decision making) the subjects were shown paired images again, but this time the pairs were either two of the circles or two of the original images of landscapes, body parts or faces. Participants were asked to choose one of each pair for a possible reward.
The researchers expected the subjects to select the images initially linked with the circles that earned them rewards in the second part of the task, and they did find that most of the participants behaved as expected, selecting images associated with the circles that had earned them $1. However, the subjects varied in their ability to make the association, and this variation allowed the researchers to study the differences in brain activity among subjects during the three stages of the experiment. The data for three of the participants was excluded because they showed no evidence of simple reward learning.
The study found that subjects in whom the hippocampus was most active in the second phase were more likely to select images associated with the rewarding circles, but those same subjects also reported being unaware of the associations, which strongly suggests the linkages were being made in the hippocampus at the subconscious level.
Subjects also showed a stronger bias towards the images associated with the reward circles if there was heightened activity during the second stage in the regions of the brain associated with vision or in the striatum, which is the reward center.
The results suggest that several areas of the brain are involved in evaluating new stimuli and associating them with previous memories, but the process is strongly associated with the hippocampus.
The findings could have application, for example, in the design of new products, which could incorporate aspects of earlier products (such as color, logo or font) to stimulate the association and produce an unconscious bias towards those products over other equally new products.
The findings also suggest that misguided biases such as racism could stem from unconscious associations. (Guilt by association is a commonly known bias.) These biases have long been known, but the current study clearly shows their association with the hippocampus.
More information: Preference by Association: How Memory Mechanisms in the Hippocampus Bias Decisions, Science, 12 October 2012: Vol. 338 no. 6104 pp. 270-273. DOI: 10.1126/science.1223252
Every day people make new choices between alternatives that they have never directly experienced. Yet, such decisions are often made rapidly and confidently. Here, we show that the hippocampus, traditionally known for its role in building long-term declarative memories, enables the spread of value across memories, thereby guiding decisions between new choice options. Using functional brain imaging in humans, we discovered that giving people monetary rewards led to activation of a preestablished network of memories, spreading the positive value of reward to nonrewarded items stored in memory. Later, people were biased to choose these nonrewarded items. This decision bias was predicted by activity in the hippocampus, reactivation of associated memories, and connectivity between memory and reward regions in the brain. These findings explain how choices among new alternatives emerge automatically from the associative mechanisms by which the brain builds memories. Further, our findings demonstrate a previously unknown role for the hippocampus in value-based decisions.
Journal reference: Science
© 2012 Medical Xpress
- A mind at rest strengthens memories, researchers find Jan 27, 2010 | not rated yet | 0
- Pure Novelty Spurs The Brain Aug 14, 2006 | not rated yet | 0
- Psychologists compare learning achievement with and without stress Aug 08, 2012 | not rated yet | 0
- Novelty aids learning Aug 03, 2006 | not rated yet | 0
- Impulsiveness linked to activity in brain's reward center Dec 20, 2006 | not rated yet | 0
- Motion perception revisited: High Phi effect challenges established motion perception assumptions Apr 23, 2013 | 3 / 5 (2) | 2
- Anything you can do I can do better: Neuromolecular foundations of the superiority illusion (Update) Apr 02, 2013 | 4.5 / 5 (11) | 5
- The visual system as economist: Neural resource allocation in visual adaptation Mar 30, 2013 | 5 / 5 (2) | 9
- Separate lives: Neuronal and organismal lifespans decoupled Mar 27, 2013 | 4.9 / 5 (8) | 0
- Sizing things up: The evolutionary neurobiology of scale invariance Feb 28, 2013 | 4.8 / 5 (10) | 14
Pressure-volume curve: Elastic Recoil Pressure don't make sense
May 18, 2013 From pressure-volume curve of the lung and chest wall (attached photo), I don't understand why would the elastic recoil pressure of the lung is...
If you became brain-dead, would you want them to pull the plug?
May 17, 2013 I'd want the rest of me to stay alive. Sure it's a lousy way to live but it beats being all-the-way dead. Maybe if I make it 20 years they'll...
MRI bill question
May 15, 2013 Dear PFers, The hospital gave us a $12k bill for one MRI (head with contrast). The people I talked to at the hospital tell me that they do not...
Ratio of Hydrogen of Oxygen in Dessicated Animal Protein
May 13, 2013 As an experiment, for the past few months I've been consuming at least one portion of Jell-O or unflavored Knox gelatin per day. I'm 64, in very...
Alcohol and acetaminophen
May 13, 2013 Edit: sorry for the typo in the title , can't edit I looked around on google quite a bit and it's very hard to find precise information on the...
Marie Curie's leukemia
May 13, 2013 Does anyone know what might be the cause of Marie Curie's cancer
- More from Physics Forums - Medical Sciences
More news stories
For combat veterans suffering from post-traumatic stress disorder, 'fear circuitry' in the brain never rests
Chronic trauma can inflict lasting damage to brain regions associated with fear and anxiety. Previous imaging studies of people with post-traumatic stress disorder, or PTSD, have shown that these brain regions can over-or ...
Neuroscience May 18, 2013 | 5 / 5 (1) | 0 |
The neural machinery underlying our olfactory sense continues to be an enigma for neuroscience. A recent review in Neuron seeks to expand traditional ideas about how neurons in the olfactory bulb might encode information about ...
Neuroscience May 17, 2013 | 4 / 5 (1) | 0 |
(Medical Xpress)—What if the quality of your work depends more on your focus on the piano keys or canvas or laptop than your musical or painting or computing skills? If target users can be convinced, they ...
Neuroscience May 17, 2013 | 3.7 / 5 (3) | 0 |
Neurological disorders can have a devastating impact on the lives of sufferers and their families.
Neuroscience May 17, 2013 | 5 / 5 (1) | 0 |
If you're a left-brain thinker, chances are you use your right hand to hold your cell phone up to your right ear, according to a newly published study from Henry Ford Hospital in Detroit.
Neuroscience May 16, 2013 | 2 / 5 (2) | 0 |
In their quest to learn more about the variability of cells between and within tissues, biomedical scientists have devised tools capable of simultaneously measuring dozens of characteristics of individual ...
24 minutes ago | not rated yet | 0 |
Scientists at Johns Hopkins have turned their view of osteoarthritis (OA) inside out. Literally. Instead of seeing the painful degenerative disease as a problem primarily of the cartilage that cushions joints, ...
24 minutes ago | not rated yet | 0 |
The hunt for an HIV vaccine has gobbled up $8 billion in the past decade, and the failure of the most recent efficacy trial has delivered yet another setback to 26 years of efforts.
4 hours ago | not rated yet | 0
The devastating effect of Alzheimer's disease on bilingual people has been thrown into focus in Canada, where the sudden loss of a second language can leave sufferers feeling like strangers in their own country.
2 hours ago | not rated yet | 0
Regular consumption of coffee is associated with a reduced risk of primary sclerosing cholangitis (PSC), an autoimmune liver disease, Mayo Clinic research shows. The findings were being presented at the Digestive Disease ...
11 hours ago | not rated yet | 0 |
Patients with treatment-resistant major depression saw dramatic improvement in their illness after treatment with ketamine, an anesthetic, according to the largest ketamine clinical trial to-date led by researchers from the ...
11 hours ago | 4.7 / 5 (3) | 0 |