Humans are wired for prejudice but that doesn’t have to be the end of the story

Check out my article leading today on The Conversation US! Posted February 4th, 2015 on the

Humans are highly social creatures. Our brains have evolved to allow us to survive and thrive in complex social environments. Accordingly, the behaviors and emotions that help us navigate our social sphere are entrenched in networks of neurons within our brains.

Social motivations, such as the desire to be a member of a group or to compete with others, are among the most basic human drives. In fact, our brains are able to assess “in-group” (us) and “out-group” (them) membership within a fraction of a second. This ability, once necessary for our survival, has largely become a detriment to society.

Understanding the neural network controlling these impulses, and those that temper them, may shed light on how to resolve social injustices that plague our world.

Our brains can almost instantly assess in-group or out-group status. Daniela HartmannCC BY-NC-SA

Prejudice in the brain

In social psychology, prejudice is defined as an attitude toward a person on the basis of his or her group membership. Prejudice evolved in humans because at one time it helped us avoid real danger. At its core, prejudice is simply an association of a sensory cue (e.g., a snake in the grass, the growling of a wolf) to an innate behavioral response (e.g., fight-and-flight). In dangerous situations time is of the essence, and so human beings adapted mechanisms to respond quickly to visual cues that our brains deem dangerous without our conscious awareness. The rub in all of this is that our brains have inherited the tendency to erroneously deem something dangerous when it is in fact benign. It is safer to make false-positive assumptions (avoid something that was good), than to make false-negative assumptions (not avoid something that was bad).

Neural structures that underlie components of a prejudiced response. The neuroscience of prejudice and stereotyping, David M. Amodio

Neuroscience has begun to tease out the neural underpinnings of prejudice in the human brain. We now know that prejudiced behavior is controlled through a complex neural pathway consisting of cortical and sub-cortical regions.

A brain structure called the amygdala is the seat of classical fear conditioning and emotion in the brain. Psychological research has consistently supported the role of fear in prejudiced behavior. For this reason, the vast majority of brain research on this topic has focused on the amygdala and the cortical regions that influence it.

Focus on the amygdala

In one study by Jaclyn Ronquillo and her colleagues, eleven young, white males underwent functional magnetic resonance imaging (fMRI) while being shown photographs of faces with varied skin tones. When they viewed black faces, it resulted in greater amygdala activity than when they viewed white faces. Amygdala activation was equal for light and dark black faces, but dark-skinned white people had greater activation than those with lighter skin tone. The authors concluded that Afrocentric features drove an unconscious fear response in white participants.

Darker faces elicited more amygdala activity when white subjects were fMRI scannned. The effect of skin tone on race-related amygdala activity: an fMRI investigation, Ronquillo (2007)Author provided

More recent imaging research has supported the intractable nature of prejudice in the human psyche. Chad Forbes and colleagues found that even self-reported non-prejudiced subjects could be prejudiced in some situations. White study subjects had increased amygdala activation while viewing images of black faces when they were listening to violent, misogynistic rap music, but not when listening to death metal or no music. Interestingly, they found that a region of the frontal cortex – an area of the brain expected to tamp down amygdala activation – was also activated.

The researchers speculated that the music reinforced a negative stereotype about black subjects, creating a situation in which the white subjects were not able to temper their prejudiced emotions. In fact, the authors speculated that the frontal cortices – generally thought of as areas of “higher” brain function – were instead recruited to help justify the feelings of prejudice felt by the participants listening to rap music.

Other research has shown that the amygdala response to out-group faces is not strictly bound to characteristics such as race. The amygdala responds to any out-group category, depending on whatever someone deems is salient information: your sports team affiliation, gender, sexual orientation, where you go to school, and so on.

Brains can control bias too

The Forbes et al study highlights that our ability to control reactionary implicit bias is dependent on the frontal cortices of the brain. A particularly important region of the cortex is the medial prefrontal cortex (mPFC).

The mPFC is the seat of empathy in the brain. It forms impressions about other people and helps us consider other perspectives. A lack of mPFC activity is associated with prejudice marked by dehumanization and objectification of others. For example, it is known that mPFC activation increaseswhen we view a person of high esteem or prestige – for example, firefighters or astronauts – but not when we view someone marked with disregard or disgust, such as a drug addict or homeless person. Men with highly sexist attitudes have less mPFC activity when viewing sexual images of female bodies. These men also believed sexualized women have “less control over their own lives.”

Taken together, it seems that though the frontal cortices are able to reduce our innate prejudices about certain people, they are greatly influenced by context. In other words, our desire to not be prejudiced may sometimes get trumped by exposure to media supporting stereotypical portrayals of certain groups. Moving forward, it is essential to take into account not only the neural architecture of prejudice, but also the context in which we humans live.

Babies aren’t born with prejudices. Babies image via

Current questions being addressed in this field of research include whether or not amygdala activation in response to those of other races is something we’re born doing or a learned phenomenon. So far, research suggests that amygdala activity in response to out-group members is not innate, and develops later in adolescence. Also, studies support the notion that childhood exposure to diversity can reduce the salience of race in adulthood.

In today’s world people are more connected than ever – from social media to Skype, to the never-ending news cycle – people are exposed to increasing diversity. Due to these advances, we as a global community are also faced with the knowledge that prejudice-based discrimination and violence still exist. It’s become a human imperative to transcend divisive impulses which no longer serve our survival. Neuroscience has started to educate us about innate human drives. It’s now up to all of us how to use this information.


Why We’re So Easily Fooled, and Why It Matters

Originally Published on December 8, 2014 in Brain Babble on

The holiday season is fast approaching, and that means gift buying. With each passing season, finding the perfect gift for loved ones seems to become more and more difficulta phenomenon not unrelated to the seemingly exponential growth in buying options each year.

So how do we do it?

Many of us would like to believe that our decision-making is based in logic and objectivity. Studies have shown, however, that our preferences are highly biased, based on our expectations.

For decades, psychological research has supported the presence of inherent bias in human perception. A 2001 study titled The Color of Odors examined the effect of color on odor and taste perception of wines. In the experiment, wine experts were presented with two glasses of wine: one red and one white. Each was asked to describe the wine as they experienced it. The experts used words like citrus, flower, lemon, and honey to describe the white wine, whereas they used words like clove, musk and crushed red fruit to describe the red.

However, all of the experts had been unwittingly duped: both glasses actually contained the same white wine, the only difference between them being a little red food coloring in one glass. Not a single expert was even able to identify that both glasses contained white wine, and they all described the colored white wine as they would have a red. This classic study reveals the power that expectations have on how we perceive the world.While this and other studies have revealed a lot about the underlying motives of human judgment, they rarely touch on the neurosciencebehind these phenomena. A 2008 CalTech study, however, began to shed light on how preconceived notions and labels influence our thinking.

In this study, subjects were placed in a functional magnetic resonance imager (fMRI) and presented with two glasses of wine, one labeled $5 and a second labeled $90. However, the subjects were not told that the wine in each glass was actually the same $90 wine. They found that the average self-reported experienced pleasantness (EP) score was greater for the wine labeled $90 as compared to that labeled $5. More important, the higher EP score corresponded to an increased blood-oxygen level dependent (BOLD) signal in the medial prefrontal cortex (mPFC) of the brain, meaning that this area was more active when tasting the wine labeled as more expensive. The frontal lobe of the cortex is an area of the brain important for high-level cognitive function and top-down processing. It has been shown to be essential for decision making, planning for future events, and reward comparison.

This study revealed that the mPFC did not respond to the wine, per se, but rather in accordance to whether or not it had received the better wine. An earlier Stanford study revealed that the mPFC responds when the outcome of a reward comparison is revealed and the mPFC is active only after a reward is gained. Therefore, the activation of the mPFC is not directly tied to true sensory signals or inherent quality, but to the markers and labels—signals of quality. The mPFC performs at a higher level of abstraction than brain areas that objectively sense the world around us. In fact, in studies involving the insular cortex—the area of the brain that perceives taste—no difference between the two wines was detected.These studies demonstrate how our own brains can fool us, stemming from the fact that different parts of it process stimuli differently. Bottom-up processing is when we perceive reality objectively based on stimulus—we let the sensations guide our perceptions. Top-down processing is when we drive our own reality based on perception. The frontal cortex’s predisposition for top-down processing is one reason why the subjects in these studies were so easily tricked, and it is why we humans are predisposed to bias.

However, expectation can influence more than just our perceptions of wines—it can influence our expectations of people, too. A study conducted by Rosenthal and Jacobson established what is known as the Rosenthal Effect, which states: The greater the expectation of achievement, the greater the level of success.

The study went like this: To test whether a teacher’s expectation of student performance affected student achievement outcomes, researchers gave an IQ exam to elementary school students and ranked them based on scores. Teachers were told that the top 20% of students have high potential to succeed and were provided with the names of these students. What the teachers didn’t know was that they had actually been given a random list of names. At the end of the school year, the researchers returned and administered the exam again to the same group of students.

What they found was astonishing: The second- and third-graders who’d been labeled as “bright” at the beginning of the year had advanced significantly beyond their peers—with significantly higher IQ scores on average. The researchers concluded that the teachers’ expectations of student achievement actually became self-fulfilling. Those students labeled “smart” actually became so. The teachers, consciously or unconsciously, paid closer attention to these students, or treated them differently when they were having difficulty. The teachers and students at this elementary school believed in the existence of “smart” and “not-so-smart” students, and so they made it their reality.

This idea extends beyond labels of intelligence: Subsequent studies have shown that labels based on race, class, and gender can influence our perceptions of people just as strongly.

All that being said, does it mean you should be doing your holiday shopping with a blindfold to protect yourself from unconscious biases? Should you blindly grope through racks of wool and cashmere to find something inherently pleasing to the touch? Probably not, though it might be worth the befuddled reactions you get from sales associates. But there is something to be said for trying to minimize harmful bias.

Holiday shopping may be a small-stakes enterprise when it comes to upholding the ideals of equality and fairness in our society, but these principles will surely slip away if we are not vigilant in maintaining our awareness of these prejudices. The goal here is not to entirely eliminateprejudice—that would be a futile undertaking indeed—but to let science enlighten our culture to them.

Minerva Studio/Shutterstock


Darley, J.M., Gross, P.H. (1983). A hypothesis-confirming bias in labeling effects. Journal of Personality and Social Psychology, 44, 20-33.

Eberhardt, J. L., Dasgupta, N., & Banaszynski, T. L. (2003). Believing is seeing: The effects of racial labels and implicit beliefs on face perception. Personality and Social Psychology Bulletin, 29, 360-370.

Knutson B, Fong GW, Bennett SM, Adams CM, Hommer D (2003) A region of mesial prefrontal cortex tracks monetarily rewarding outcomes: Characterization with rapid event-related fMRI. Neuroimage 18(2):263–272.

Miller EK, Cohen JD (2001). “An integrative theory of prefrontal cortex function”. Annu Rev Neurosci 24: 167–202. doi:10.1146/annurev.neuro.24.1.167

Rosenthal, R., & Jacobson, L. (1992). Pygmalion in the classroom: Expanded edition. New York: Irvington Winawer, J., Witthoft, N., Frank, M. C., Wu, L., Wade, A., & Boroditsky, L. (2007).

My first post on The Conversation US! What is SAD?

Explainer: what is seasonal affective disorder? Originally published on October 31st, 2014 on the

by: Caitlin Millett


It’s that time of year again – the end of daylight savings and the beginning of the dark season. While many of us look forward to seasonal festivities, millions can also expect feelings of depression, fatigue, irritability and poor sleep. This form of mental illness, commonly known as the “winter blues”, is Seasonal Affective Disorder (SAD).

SAD occurs most frequently in populations furthest from the equator. It is estimated that 1-2% of North Americans have a mood disorder with a seasonal pattern, with 10% of New Englanders versus 2% of Floridians affected. Symptoms include feelings of hopelessness, low concentration, sluggishness, social withdrawal, unhappiness and irritability.

Circadian rhythms

Decades of research has uncovered the culprit behind SAD: lack of sunlight and disruption of circadian rhythms.

A circadian rhythm is a process the body goes through following a 24-hour cycle. Circadian rhythms are entrainable, that is, they can be reset based on an external influence like light. The human sleep cycle is an example of a circadian rhythm and is shifted based on light levels.

This is why we experience jet lag after travelling across time zones. Similarly, seasonal changes can affect circadian rhythms, due to shorter days and loss of daylight in winter months.

Daylight and your brain

Although most people are able to adapt to the change in seasonal light levels, what makes some vulnerable to seasonal depression? To understand how sunlight affects mental health, we need to first understand how our brains use sunlight to modulate certain behaviour and hormonal processes.

The pineal gland

In humans, the hormone melatonin is an marker of external darkness. When darkness descends, melatonin is secreted from a structure called the pineal gland, a pine cone-shaped endocrine gland located in the center of the brain. This gland modulates sleep patterns in both circadian and seasonal rhythms. The secretion of melatonin from the gland corresponds to the length of darkness; as the nights get longer, melatonin secretion follows suit.

The timed production of melatonin is controlled by another area in the brain – the suprachiasmatic nucleus (SCN) of the hypothalamus. The hypothalamus is the primary hormone-producing structure of the brain, controlling body temperature, sleep, circadian rhythm, moods, sex drive, thirst, hunger, and the release of other hormones. The SCN is the “pacemaker” of the brain, consisting of about 20,000 neurons. It maintains an autonomous signal which operates on an approximate 24-hour cycle. Even outside the body, as seen in the laboratory, SCN neurons will continue their circadian cycling. The SCN regulate sleep cycles, alertness, hormone levels, digestive activity, body temperature and immune function.

The eyes have it

Many studies have cited disruption in the circadian control center as a contributing factor to several mood disorders, including major depressive disorder and bipolar disorder. Even though these illnesses are not necessarily seasonal, both entail loss of consistent sleep/wake cycles as seen in SAD.

However, unlike depression and bipolar disorder, the major form of therapy for SAD is the use of artificial light, which alleviates symptoms in 50-60% of people.

Light boxes provide relief to many, and come in a few varieties. Typically light boxes are advertised as broad spectrum light sources, which is pure white light. Some light boxes can also give full spectrum light, which has a broader range of wavelengths, including infrared to near ultraviolet light, and everything in between.

Although full spectrum light boxes provide a source closest to that of natural sunlight, they usually come with a screen to protect against UV rays. In this way, it is often preferable to use a broad spectrum light box to avoid UV ray exposure.

The use of light as a treatment indicates that it is not only the SCN implicated in the onset of this disorder, but there may be a contributing cause related to how we process light in the eye. In fact, various studies have pointed to mutations in a retinal pigment called melanopsin as a source of SAD.

Melanopsin is a molecule which absorbs light in the eye, and through a chemical change, can translate external light levels into messages for the brain. Unlike rod and cone cells, melanopsin is found in specialized cells of the eye which react slowly to changes in light, and are known to regulate the timing of circadian rhythms. Whereas rods and cones are responsible for the detection of motion, color, images and patterns, studies have shown that melanopsin-containing cells contribute to various unconscious responses of the brain to the presence of light, including circadian rhythms.

Overall, melanopsin can translate messages directly from the eye to the SCN. This in turn influences the production of melatonin. The SCN not only projects to the pineal gland, but has wide-ranging connections to other important areas in the brain. So if there is disruption in melanopsin in the eye, which is passed on to the SCN, the potential exists for many areas to be affected.

Though SAD is not fully understood, genetic research into melanopsin, as well as hypothalamic genes associated with serotonin production, holds promise.

In the meantime, the use of antidepressants, therapy, and artificial light may help SAD sufferers through the upcoming dark months. And with holidays approaching, spending time with family, friends and good food is something we can all benefit from.

Should Graduate Students Meditate?

My most recent post for Lions Talk Science!

Lions Talk Science

By: Caitlin Millett, 3rd year PhD candidate in the Neuroscience Graduate Program

“Educating the mind without educating the heart is no education at all.”
― Aristotle

7912377858_d1e19cbf35 Moyan Brenn (Flickr)

Meditation is an ancient practice dating back at least three millennia. It’s a fundamental component of many Eastern religious traditions and belief systems including Hinduism, Buddhism and Daoism, to name just a few.

The term meditation refers to a broad variety of practices meant to clear the mind and build compassion and kindness. It may also ease some health issues, such as high blood pressure, depression, anxiety, and stress. The National Center for Complementary and Alternative Medicine (NCCAM), a component of the National Institutes of Health, notes that:

“Meditation may be practiced for many reasons, such as to increase calmness and physical relaxation, to improve psychological balance, to cope with illness, or to enhance overall health and well-being.”

Due to its purported benefits, recent…

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Sexual objectification is linked to coercive behavior in heterosexual relationships

To sexually objectify someone means to think of them as an object whose sole purpose is to fulfill sexual desires, rather than as a human being with thoughts and emotions.

“Objectification from one’s romantic partner may be particularly powerful, given that physical attraction is a key element of romantic relationships and investment in romantic relationships is a feminine norm.”

A new study published in Psychology of Women Quarterly The Object of Desire: How Being Objectified Creates Sexual Pressure for Women in Heterosexual Relationships found that females who are sexually objectified by their male partners tend to experience sexual pressure (the belief that a man deserves sex and the woman is obligated to provide it) and coercion (generally or through violence and manipulation) within their relationship.

Sexual objectification of female bodies is an epidemic in this country, and is influenced largely by media’s portrayal and overall hypersexualization of women. For an overview on male gaze theory, and the impact of media’s portrayal of women in society, please check out my blog, and specifically the post The Male Gaze, Part II: Consequences.


What is even more troubling than the objectification itself is the disheartening conclusion from the study- that women tend to internalize their own objectification. Internalized objectification results in feelings of shame and low self-esteem, which makes it more difficult for a woman to assert herself. Moreover, women who are objectified find it more difficult to express what they want and don’t want to do sexually.

In order to fully address the issue of intimate partner objectification, a wholistic perspective of how our culture treats women is necessary. Research has shown that men who consume  media with sexually explicit and degrading images of women are less empathetic to female victims of  rape, and are more likely to sexually coerce and harass women. Considering that hypersexual images of women are ubiquitous in media, it’s difficult for any woman to escape these negative impacts.

The authors of this study encourage people in relationships to be aware of objectification, and to take proactive measures to  prevent and/or remove it from their intimate lives. Women who are objectified by male partners tend to experience lower levels of sexual satisfaction, not to mention many other negative impacts to her self-esteem, self worth and body image. Therefore, it is of the upmost importance for women to remove themselves (if possible/safe) from these types of situations.

“How Can I Join a Lab as an Undergraduate?”

A post by me from Lions Talk Science!

Lions Talk Science

By: Caitlin Millett, 2nd year PhD candidate in the Neuroscience Program

girls in a labThere are many benefits to participating in undergraduate research. In most cases, especially in STEM fields, writing a research thesis is a requirement for graduation. Moreover, it’s necessary for a strong application to graduate or medical school.

That said, there are many aspects of choosing a lab that can be quite nerve racking. In order to avoid common pitfalls on the path to a thesis, students should be aware of the most important aspects of this process.

Here are a few gems of wisdom for a lab-bound undergrad…

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Congratulations to Winners of the 1st Annual Lions Talk Science Blog Award!

Lions Talk Science

10553501_493503330779647_3927423967298963676_nThe judges’ scores have been tabulated, and we’re thrilled to announce the winners of our inaugural blog award!

Thanks to everyone for participating. We’ll be back with a shiny new prompt next year!

We’d like to extend a huge thanks to Dr. Michael Verderame, Dr. Kirsteen Browning, Amanda White, and Jordan Gaines Lewis for judging the competition this year.

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