Discrete versus dimensional models of emotion?

Eliza Bliss-Moreau
Eliza Bliss-Moreau

Over the last number of months as an Associate Editor at Emotion, as well as a reader of the literature, I have seen an increasing number of scholars refer to “discrete emotion models” and pit them against “dimensional emotion models” in order to set up a primary hypothesis and its alternative.  This is a false dichotomy.  My challenge as an editor is that I have not been able to find a singular “quick read” piece of writing in the literature articulating why a discrete versus dimensional contrast doesn’t make sense (although there are longer papers on this that do make this point such as this, this, this, and this – if you know of others that are near and dear to you, send them my way).  I did a quick – entirely nonscientific – review of papers with the keyword “emotion” and “discrete or dimension or dimensional” published in 2017 and 2018 and there is some evidence that this is a problem in the published literature as well.  My first take was “I should write a manuscript about this”, and I may, ultimately. My goal here, however, is not to call people out for this analytical problem per se but to provide an explanation as to why pitting discrete emotion models against dimensional emotion models is logically problematic, so that folks can fix it if it is in their writing (or thinking) or not make it in the first place. I don’t see any way around that goal if I were to undertake writing a manuscript which would require appropriate scholarly referencing.  So, writing a blog post seemed like a good option.

The problem
There are lots of theories and models of emotion that focus on discrete emotions – how they come to be, their outputs, their functions, and so on.   They vary widely in their hypotheses about all of those features of emotion. But there is no dimensional theory of emotion.  Dimensions  – typically valence and arousal –  are characteristic of affect [i], not emotion.  According to a number of the major theories in our field, affect is thought either to be the causal foundation of emotion or one of the most important components of emotion.  Saying that affect is a causal foundation or critical component of emotion is very different, however, from saying that affect is emotion – and so, theories of emotions which recognize differences between affect and emotion are not reductionist about emotions.  According to these theories, whatever else emotion is, it is something “more” than just affect. It is therefore a mistake to talk about theories of emotions as if they are dimensional.  As a result, there is no way to pit “discrete emotion models” against “dimensional emotion models” because a) there is no dimensional emotion model, only dimensional affect models and b) emotion theories that hypothesize that multiple dimensions of affect underlie emotions in some way or another frequently hold that these emotions can be separated into distinct types and kinds, and therefore are, metaphysically speaking, discrete entities.

The background
It goes without saying that there are many different theoretical and methodological approaches to the study of emotion. Over the last decade or so, two types of theories have dominated discussion and study (despite both being around for much longer) – what we call the Classic View of Emotion (CVE) [ii] and Theories of Constructed Emotion (TCEs).  I use this terminology with very specific intentions, not just as shorthand labeling to differentiate my writing from that of other scholars.

The CVE says that emotions are precipitated by events and then produce a stereotypical set of outputs in the face, voice, autonomic/peripheral nervous system, behavior, and, or brain.  There is a predictable mapping between the types of events that cause emotions and specific emotions. Further, each emotion is thought to have some sort of specific pattern of physiological and behavioral outputs. Because of this, to understand the emotion state of another individual, an observer (who could be the self) can “read” the outputs and, because the relationship between the outputs at the emotion causing them is mapped, infer the identity of the emotion causes the relevant outputs.

The interesting unit of analysis from the CVE can be at any step of the process – the event that causes the emotions, the process by which the effects of the event are translated into the emotion, the phenomenological experience of the emotion, the process by which the emotion generates to the outputs, the type of outputs generated by the emotions.  CVEs stipulate that some special set of, or number of, emotions cannot be reduced to more fundamental or basic parts. This belief is reflected in the moniker of one type of CVE – “basic” emotion theory.

“Basic” emotion theories typically stipulate that a small set of emotions (e.g., 5 or 6) are unique kinds.  This means that they are held by the theory to be fundamental or basic [iii], irreducible, and have a modular neurobiological architecture [iv].  These theories sometimes stipulate that more “complex” emotions (e.g., guilt) may be built via combinations of basic emotions, but even those more emotions must follow the event–>emotion–>output schema according to this theory (a view articulated here, for example). Basic emotion theories argue that relationships between events, emotions, and outputs is biologically hardwired and evolutionarily conserved; these assumptions have guided investigation into the neurobiological basis of emotion (e.g., in nonhuman animals, and in humans) and evolutionary emergence of emotion (for example).

Basic emotion theory is arguably the dominant theory that embodies a CVE, but it is not the only theory, hence my use of “CVE” and not “Basic Emotion Theory” (or something similar) to name this perspective.  For example, most appraisal theories embrace a CVE insofar as they evaluate the specific pattern of cognition (called appraisals) that people make following events that lead to emotion – that is the process by which the event translates to emotions.

CVEs do say there are discrete emotions, whether they stipulate that a small set of emotions is biologically basic and hardwired or focus on the process by which an event precipitates an emotion or even the numbers of discrete emotions that exist.  The unit of analysis is typically specific, discrete emotions and these emotions are thought to be the source of the lion’s share of variance in outputs.  These are the theories, I believe, that scholars think they are referring to when they discuss “discrete emotion models” because of their emphasis on specific emotions (like happiness, sadness, fear, disgust, elation, and so on). Further, CVEs do not typically discuss or evaluate the importance of valence and arousal – the dimensions of affect.

Valence and arousal are the dimensions of affect, which, according to TCEs forms the basis of discrete emotions.  TCEs stipulate that emotions are not hardwired modules. Instead, TCEs say that each emotion is a causal by-product of a complex interaction of more basic parts, and that these parts can vary dramatically depending on age, behavioral context, cultural context, conceptual knowledge, and any number of other important physiological and cognitive factors [v].  Nevertheless, TCEs still recognize that emotions are discrete things. TCEs differ to some degree in the ingredients that they think are critical for the emergence of discrete emotions – hence Theories of Constructed Emotion and not Theory of Constructed Emotion.  But all TCEs hold that affect is a critical ingredient.

Affect is a state that is characterized by some degree of valence (hedonics, pleasantness to unpleasantness) and arousal (physiological activation) and can, but need not be, felt consciously.  People can report on their affect (“I feel good” or “I feel bad”) or, people can report on their emotions and affective information can be extracted from those reports (e.g., one characteristic of happiness is a good or pleasant feeling). That is, affect can be organized according to dimensions (valence and arousal). That is the case because discrete emotions are organized in a systematic way with regards to valence and arousal.  Happiness?  Positive valence, just slightly activated/aroused.  Depression?  Negative valence, very deactivated.  Fear, anger, disgust?  Very negative, very activated/aroused, and so on.

TCEs say that affect is an essential component of emotion, but they do not say that affect is emotion – and so they do not reduce emotion to affect. According to TCEs, a discrete emotion has affective components, but the affective states that are components of emotions are not alone sufficient to determine the identity of the emotion of which they are part. For example, there are a slew of negative, high arousal emotions which share a negative, high arousal affective state but are not the same emotion – think anxiety, disgust, anger, and fear.  The same affective state can thus be part of a number of discrete emotions depending on the context, what the person knows about emotion, past experiences, the language the person speaks, social norms, and so on.  As a result, it does not follow to say that emotions, according to TCEs, are (or can be described by) dimensions. Scholars guided by TCEs, just like those guided by CVEs, study discrete emotions – but they may be equally likely to study the various other ingredients that go into cooking up emotions, including affect.

Why does the distinction between discrete emotions and the dimensions of affect matter?
It is important to be clear about whether we are testing hypotheses about emotions (which nearly everyone agrees are discrete entities) or testing hypotheses about affect (which everyone agrees can be analyzed as falling into at least two continuous but bounded dimensions), or testing hypotheses about some combination of the two–for example, when we ask whether (discrete) emotions or (degrees of the dimensions of) affect capture more of the variance in a given situation. Keeping this distinction in mind can help us develop strong, testable hypotheses about the nature of emotion.

For example, the goal of my lab is to understand some of the biological mechanisms that generate the emotions – and we do that work largely in nonhuman animals.  While there is huge debate about the nature of nonhuman animal emotions, I have argued that affect is species nomothetic – at least in mammals who share a similar central-to-peripheral nervous system structure.  If this is the case, and if a given behavioral or physiological phenomenon is driven by affect and not discrete emotions, then we can hypothesize that it has a homolog in nonhuman animals.

Another issue in the nonhuman animal literature that appears regularly is that scientists will make strong claims about animals’ abilities to perceive emotion stimuli when they are actually testing an affect hypothesis.  For example, in a recent study, when goats were shown pictures of human faces generating behaviors typically associated with anger and those typically associated with happiness, goats spent more time investigating the “happy faces”.   The take home message, amplified by the media, was that a) goats understand human emotions or “goats can read human emotions” and b) “goats prefer happy people”.  That may very well be true, but given the experiment as conducted, there’s actually no way to determine whether goats prefer happy people or simply pleasant, neutral arousal people compared to negative, high arousal people.   It’s entirely possible that when a happy face was compared to a serene face, goats might opt for serenity.  If this was the case, one starts to build an argument that their choice has nothing to do with valence at all (let alone emotion), but rather arousal – lower arousal faces might be favored.

The hope
What CVE and TCE theorists, as well as scientists studying discrete emotions and the dimensions of affect, all have in common is the goal of understanding the mechanisms that generate and subserve emotions. My hope is that remaining clear about the difference between a hypothesis that is about discrete emotions versus a hypothesis that is about the dimensions of affect will speed those discoveries.

 

 

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[i] Thus, there is a dimensional theory of affect.  Valence and arousal aren’t the only dimensions that have been proposed to organize affect, but they are the dimensions that consistently appear in analyses of self-reports of emotion experience and judgements of emotion stimuli.  Jim Russell’s 1980 paper is a classic on this .  Here’s a resource of a broader discussion of affect.  And here’s a recent paper which proposed additional dimensions of affect.

[ii] As far as I know this labeling originated with Lisa Barrett and a version of it (the Classical View) is used throughout her book, How Emotions Are Made.

[iii] For examples of modern articulations of basic emotion theory see: here, here, here, here, and here.

[iv] There are lots of ways that a phenomenon can be modular, for example if the same stimulus or event produces a single emotion, then that Stimulus-Response link is modular.  When framed as a neuroscience argument, modularity has typically been interpreted as their being discrete neural and biological circuity for each emotions – such that emotions have, as Lisa Barrett calls them in here book, “fingerprints” in the brain (as well as voice, face, etc.).

[v] For a historical review of Theories of Constructed Emotion.  For an edited volume on Theories of Constructed Emotion (note that many of the chapters appear to be accessible on the authors’ websites).

The emotional basis of prejudice

Kristen Lindquist
Kristen Lindquist

Across the US and the globe, there has recently been an uptick in prejudice. Prejudice is defined as a hostile or negative attitude towards others on the basis of their group affiliation, whether that group is based on race, religion, sex, political ideology, country of origin, mental abilities, or any category. People can be prejudiced towards anyone on the basis of almost anything, and history is rife with examples. Sadly, perhaps one of the most enduring features of human behavior is that people find reasons to like people who are like them, and dislike people who are not.

Decades of research show that prejudice is a deeply emotional phenomenon. Anyone who is being honest can admit to at circle-312343_960_720least occasionally feeling hatred towards their political enemies, fearful towards people who look and sound different from them, or disdainful of people who hold different religious views. Our emotions are powerful determinants of behaviors, so it sometimes seems that once these feelings are set in motion, there is no allaying prejudiced behavior. Yet research that my collaborators and I recently published in the journal Emotion demonstrates that not all emotions are equal when it comes to prejudice.

We’ve long known that even if people don’t want to feel negative towards people who are different from them, they automatically do so. This negativity can stem from any number of factors, including the fact that our society associates negative things with a certain group of people, that you’ve had a negative experience with a single individual from a group and now you generalize to that whole group, or even the fact that you just feel a little uncomfortable interacting with people who are different from you. Even well-meaning people sometimes feel uncomfortable with people who are from another race, demographic, or religion because they don’t know how to act or are afraid that they’ll say the wrong thing. These feelings typically arise as a gut reaction when you interact with a person from another group, but our research shows that precisely how you interpret that gut reaction makes all the difference for whether you feel prejudice or not towards that person.

In our research, we studied prejudice towards Black Americans amongst White American participants. We chose to study these groups given the historical prevalence of prejudice towards Black Americans in the US, but in principle, we could have studied any number of groups across time and space, and the results would be similar. In our studies, we first measured White participants’ gut reactions towards pictures of Black male faces. We did so using a procedure called the Affect Misattribution Procedure (AMP) that allows us to assess to what extent people have negative gut reactions towards certain stimuli. To do so, participants are very quickly shown pictures of either White or Black faces prior to seeing an ambiguous stimulus that participants don’t know the meaning of (e.g., a Chinese character or an abstract shape). Participants are then asked to what extent they think that the ambiguous stimulus is good or bad. Research shows that the more that people have negative gut reactions to Black faces, the more likely they are to believe that the ambiguous stimulus is bad after being very briefly exposed to Black, but not White faces. This is because they misattribute their negative gut reactions towards the faces to the ambiguous stimulus. The AMP regularly shows that people vary in how much they have negative gut reactions to Black faces, with some people having highly negative gut reactions and some people having rather neutral gut reactions to Black faces. Critically, we hypothesized that it was not just how negative participants’ gut reaction was that mattered for prejudice, but also how they made meaning of that gut reaction as feelings of specific emotions. We reasoned that if participants interpreted their gut reaction as fear towards Black Americans that this would result in more prejudiced behavior towards Black Americans. In contrast, we predicted that people who had negative gut reactions, but who interpreted their reaction as sympathy towards Black Americans due to their plight with racism and oppression throughout US history, would be less likely to show prejudiced behavior.

To test this hypothesis, we manipulated how people made meaning of their negative gut reactions. After completing the AMP, half the participants were told that it assessed feelings of fear towards Black Americans. The other half of participants were told that the AMP assessed feelings of sympathy towards Black Americans. Next, we measured participants’ reports of fear, sympathy, and their tendency to literally see Black faces as more aggressive. We found that only those participants who scored highly on the AMP, demonstrating their negative gut reactions to Black faces, who were also encouraged to interpret their reactions as fear were more likely to report finding Black Americans as threatening. Those participants were also more likely to see Black faces as more aggressive in a perceptual test. In contrast, participants with negative gut reactions on the AMP who interpreted their reactions as sympathy were less likely to report fear and to see Black faces as aggressive. Participants who were encouraged to interpret their gut reactions as fear were also more likely to show skin conductance responses–a measure of how much sweat is secreted on the skin and a physiological measure of increased emotional reactions–to pictures of Black faces.

These findings are evidence that we are not necessarily slaves to our emotions when it comes to prejudice. Even if you have negative gut reactions to people from another group, it’s how you make meaning of those reactions as specific emotions that ultimately matters for prejudice. These findings ultimately suggest that we can combat prejudice by changing people’s gut reactions and by changing how they make meaning of those gut reactions as specific emotions. Although changing the latter might ultimately be the most fruitful, it’s also likely to be difficult to do, as people’s gut reactions are automatic and unbidden. We might be better off getting people to learn to make meaning of their gut reactions in a more prosocial manner.

Photo credit: https://pixabay.com/en/circle-hands-teamwork-community-312343/

 

Does labeling your feelings help regulate them?

Kristen Lindquist
Kristen Lindquist

One of the mainstays of psychotherapy is the idea that talking about your emotions—or even writing about them—can help you to regulate them. Mindfulness-based approaches from Buddhism offer similar outcomes—the idea is that if you are “mindful,” or aware, of your feelings, then they won’t seem as strong. Until recently, it was not well understood how, or even why, labeling your feelings worked to reduce them. In some ways, it seems too simple to be true. Yet growing evidence from neuroscience suggests that labeling your feelings is in fact a good idea; telling your kids (or your spouse) to “use their words” when they’re upset just might work.emotions_-_3

In a recent paper from my lab, my collaborators and I explored the neural mechanisms at play when people are prompted to label their emotions versus when they are not prompted to label their emotions. This paper was particularly powerful because it used meta-analysis to summarize the findings across 386 neuroimaging studies of emotion (for more on the neuroimaging of emotion, see our recent post). This means that we were able to say which brain regions were consistently more active across 386 studies when individuals were prompted to label their emotions versus were not prompted to label their emotions. In many cases, participants had no clue that labeling would have an effect on their emotions. In fact, most studies were not explicitly designed to even test this hypothesis, they just conveniently asked participants to label their feelings as part of their study design (to check that participants were in fact experiencing the desired emotions, to ensure that participants were paying attention, etc.). Thus, our paper offers a unique lens for examining whether drawing people’s attention to emotion labels alters their brain activity while they are experiencing emotions.

Our findings confirmed the idea that labeling helps regulate your emotions. We found that when labels were present—at any point—in an experiment (prior to experiencing emotions or during experiences of emotions), this was associated with more consistent increases in prefrontal and temporal regions of the brain during emotional feelings. Critically, these brain regions are responsible for retrieving concepts and elaborating on their meaning. Take a second and think about the concept of “anger”–what does it mean? What does it feel like? What happens when you’re angry? You’re activating these regions now. This means that merely seeing a word such as “anger,” “fear,” or “disgust” prior to viewing a negative image may cause your brain to start retrieving knowledge about specific emotions and to start categorizing what you’re feeling, putting your feelings of negativity into more specific words. Consistent with the idea that labeling your feelings reduces them, these regions are also known to be consistently involved in deliberate emotion regulation when people try to rethink, or “re-appraise” the meaning of their initial emotional responses to a situation (e.g., “maybe I don’t feel sad the new job didn’t work out, I feel relieved…”)

In contrast, when emotion words were not present in experiments and participants were just experiencing emotions unfettered, we found greater activity in the amygdala. The amygdala is well-known to show increased activation during emotions and may be particularly involved in intense or impactful experiences. We also know that the amygdala has increased activation to ambiguous stimuli and situations. Together, these findings suggest that when you’re not prompted to access emotion words prior to viewing a negative image, your feelings may be more intense and harder for you to understand. Consistent with this interpretation, other classic findings on emotion labeling demonstrate an interplay between prefrontal regions involved in representing words and the amygdala–greater increases in word-related regions result in greater decreases in the amygdala during emotional experiences.

Taken together, our findings begin to shine light on the neural basis of why putting feelings into words may work. Teaching people to become more mindful of their feelings, or to become better at labeling their feelings in nuanced ways (a facet of “emotionally intelligence”) may be a fruitful route for getting emotions under control. In fact, kids who “use their words” following emotional intelligence training do better at school and have more positive relationships with other kids and teachers. The next time you’re feeling bad, try labeling it. You might just feel better.

 

Photo credit: https://en.wikipedia.org/wiki/Emotion

Emotional Yoga: The importance of emotional flexibility for emotional well-being

Tom Hollenstein
Tom Hollenstein

Whether you are frequently wearing Lulu Lemon gear or not, it is difficult to miss the assurgency of yoga as a popular fitness activity. Taking the emphasis away from measurement-based exercise, like marathon running or bench presses, yoga is first and foremost about flexibility. Breathe. Stretch. Relax. Repeat.

In a similar way, one branch of emotion research over the past decade has begun to show the benefits of emotional flexibility.

In the most general sense, flexibility requires change in response to an event. With objects, as with bodies, this is often reflected in bending or changing shape somehow in order to accommodate shifting conditions without losing integrity. The opposite, then, is rigidity, where the object or body resists and retains its pre-existing shape. At its core, the concept of flexibility/rigidity is all about adaptation to local conditions in the environment.

With emotional flexibility, the same distinctions apply.

From moment-to-moment, emotions ebb and flow in a constant stream from one state to the next. A simple ritual of reading the newspaper can create a sequence of anger at a politician, sadness about the passing of a favorite celebrity, and a chuckle from the cartoon on page 12. Interacting with other people also punctuates that ebb and flow through complaints, joking, or interest.

flexible-emotions-Google-SearchA group of researchers led by Peter Kuppens and Peter Koval have examined this ebb and flow as emotional inertia, or the tendency to remain in an emotional state, even when conditions are changing (rigidity). To measure inertia, they use a type of correlation called an autocorrelation, which refers to the degree of correlation between a first moment (let’s call it time 1) with the next moment (let’s call it time 2) and so on. Higher autocorrelations of emotional states means that a person’s emotions are similar across multiple instances and that they are not changing very much. This indicates greater rigidity. Imagine being stuck in an angry mood all day and not reacting positively when you see an old friend. This would be pretty rigid. Now you might think that the reverse could be a good thing—getting stuck in a positive mood in the face of negative events, but this can be rigid too. Imagine you stay positive in the face of a slew of negative events during a really bad day (e.g., you get passed up for a promotion, you learn a friend is sick, you get in a fender-bender on the way home). This might buffer you from the effects of the negative events, but staying positive might also mean that you’re not appropriately reacting to those events or doing anything to change them. It might be more adaptive to get sad or angry when you get passed over for a promotion because it will make you try harder in the future. Consistent with this logic, a series of studies demonstrated that higher inertia, of both positive and negative emotions, has been associated with rumination and low self-esteem, but especially depression and the onset of depression in adolescents. Getting stuck, even in positive states, is not desirable.

But individual’s emotions don’t rise and fall in a vacuum. Most of the time, one’s emotions are ebbing and flowing because of interacting with someone else, whose emotions are also ebbing and flowing. Now add a third person. How can we measure that complexity?

My research group examines emotional flexibility among two or three interacting people by first viewing them as complex dynamic systems. Without getting too technical, the idea is that two people – let’s call them a “dyad” (as opposed to a monad or triad) – form a system of mutual influence on each other. The emotional patterns or “dynamics” of the interaction reveal the nature of that system. At a relatively simple level, we can characterize these dyadic systems as more or less flexible by measuring (1) the range of emotional states experienced; (2) the number of changes in emotional states experienced across time; and (3) the tendency to have short vs. long durations in emotional states. The image below shows the difference between a flexible mother-child dyad discussing a conflict they have at home and a rigid dyad doing the same thing.

Flexible gridrigid grid

Figure from Hollenstein, T. (2013). State Space Grids. New York: Springer.

These state space grids depict all possible emotional states of the mother (horizontal axis) and child (vertical axis) along 5 categories of different types of emotional experiences (e.g., a Hi Pos experience might be feeling excited whereas a Lo Pos experience might be feeling calm). This is simplified for the sake of illustration but can be done with any type of emotional experiences. Each box or cell of the grid represents one state; for example, the bottom left cell is for those moments when both mother and child are in highly negative states (e.g., angry, anxious). The dots and blue lines trace the sequence of those states across the interaction, and the size of the dot indicates how long they were in that particular state. Thus, you can see that the flexible dyad on the left has a greater range of states, (more cells occupied), makes more transitions (more lines), and has shorter durations (smaller dots) than the dyad on the right. The pattern for the flexible dyad on the left is like a movie, with the parent and child sharing and exchanging emotional expressions in fluid motions. The pattern for the rigid dyad on the right is like a series of still photographs, with the parent and child posing for a while and then shifting poses only occasionally. Using this technique, my colleagues and I have been able to show how:

 

Although it is not immediately intuitive, these studies indicate that these effects occur above and beyond emotional intensity or the emotions being experienced – inertia and rigidity in both positive and negative states is problematic. The take home message is clear: experiencing and expressing emotions in a flexible way is generally indicative of healthy functioning in day-to-day life.

Colloquially, it is common to use flexibility and rigidity when describing others. We praise people for going with the flow, chilling out, or rolling with the punches, but then denigrate the stick in the mud or someone stuck in a rut. Perhaps what we are picking up on is a person’s ability to move in and out of emotional states with relative ease. In addition to making sure to do your sun salutations or enough reps, it is just as important to stretch your emotional muscles.

 

Photo credit:http://www.psycholawlogy.com/wp-content/uploads/2013/06/flexible-emotions-Google-Search.png licensed via Creative Commons

 

Where in the brain are emotions?

Kristen Lindquist
Kristen Lindquist

This post is the latest in our Introduction to the Neuroscience of Emotion series. It discusses research using healthy human subjects and functional magnetic resonance imaging (or fMRI for short) to understand the brain basis of emotions. In coming months, we’ll have posts about studying individuals and animals with brain lesions as well as other neuroscience tools.

According to Aristotle, emotions come from your heart. In his view, the brain is just a pile of meat that is used to cool the blood. We’ve learned a thing or two about the structure and function of anatomy since the time of Aristotle; almost everyone today agrees that emotions—and mental life, more generally—originate in the brain. But, the question that remains for modern neuroscientists is how this happens. Philosopher David Chalmers calls this “the hard problem” for a reason – understanding how the brain creates conscious experiences such as emotions is extremely challenging. Despite how hard this problem is, we’ve learned a lot over the past several decades about how the brain creates the mind, and in particular, how the brain creates our emotions.

One of the major focuses of my laboratory is to understand how emotions emerge from the complex firing of neurons across the brain. We typically study emotions in healthy adults, meaning that we’re interested in how emotions work when people are functioning optimally. Knowing how the brain creates emotions in healthy people helps scientists to begin to target what goes wrong when someone suffers from a mental disorder such as anxiety or depression. The majority of our research uses neuroimaging—or what is called functional magnetic resonance imaging (fMRI for short). We use the same MRI machine that your doctor uses when she examines a tear in your knee, although we put people in the scanner head-first to examine their brain activity. This feat is accomplished via a fortunate property of the blood—it has different magnetic properties when it is carrying oxygen to your neurons v. when the neurons have used up all its oxygen; changes in how much oxygen are present in brain tissue can be detected by the MRI machine. Since “active” neurons need more oxygen, we can identify regions that are relatively more active during one mental event (e.g., feeling excited about an upcoming party) v. another (e.g., feeling neutral about making dinner tonight). In our studies, we ask people to experience certain emotions by showing them evocative images (e.g., a picture of a striking snake), having them recall emotional events (e.g., the death of a loved one), or even putting them in emotional situations (e.g., telling them they need to give a speech that we will evaluate) and examine which brain regions are more “active.” Decades of research have now examined this question and have revealed some interesting and surprising findings.

From Lindquist et al. (2012)

For a long time it was assumed that each emotion has its own neural real estate in the form of dedicated neural circuitry that is responsible for its creation. This can be seen in the belief that an emotion comes from certain brain area (e.g., the amygdala) or a network of areas in the evolutionarily “old” portion of the brain (e.g., a network in the brainstem and other regions below the evolutionarily “new” cortex). However, despite what many people (scientists and non-scientist alike) believe to be true, we do not find that there is one region or circuit for a given emotion (e.g., fear). One of our most comprehensive projects was a “meta-analysis” that summarized the findings of all of the existing fMRI studies to date. Our method was designed to reveal which brain regions were consistently active across different studies and types of emotion (anger, disgust, fear, happiness, sadness) and which brain regions were specifically active during certain emotions (anger v. disgust v. fear v. happiness v. sadness). We found that much of the brain is consistently active when someone is “having an emotion”—not just the brainstem and subcortical regions (see figure above: regions in pink, orange and yellow represent regions that are consistently active across all studies of anger, disgust, fear, happiness and sadness). What was interesting about these consistently active regions was that they included brain areas that we know are involved in the types of “hot” body changes that accompany emotions (e.g., increases in heart rate, respiration, etc.), but they also included regions associated with the type of “cool” so-called cognitive functions aren’t generally associated with emotions such as attention, memories, and language. Each type of brain region was involved in all the emotions studied. Moreover, not a single brain region in our analysis was specific to any given emotion. For instance, the amygdala was not the brain basis of fear as is typically assumed (for another recent discussion from renowned neuroscientist Joe LeDoux see here). Instead, the amygdala was active across every type of emotion experience we looked at in our analysis (including fear but also anger, disgust, sadness, and happiness).

Brain_network

My latest research demonstrates that these brain regions are not just acting alone, but in concert with one another as parts of complex networks (see figure to the left for an image of what brain networks might look like–dots represent regions in the brain and lines represent connections between different regions). Take a minute and think about your social networks—you are probably part of several different social networks consisting of people who are connected by some function: you might have your work network, your family network, your neighborhood network, your exercise network, your school network, etc. Brain networks are just like this, except they are groups of brain regions working together to serve some function.

An emerging idea in neuroscience is that these groups of brain networks—what we call functional networks—are kind of like the basic “ingredients” of the brain. Just like ingredients in your pantry, they combine together to produce more complex products. Just as oil, flour, baking soda, and water can be combined to make cookies, pancakes, breads, etc. different brain networks supporting basic functions combine to create emotions, thoughts, perceptions, and all the mental stuff we experience on a day to day basis. We are finding that the particular combination of these network-based “ingredients” differs when you’re experiencing anger v. fear (see here), and even when you’re experiencing a thought v. an emotion (see here).

What’s compelling about these findings is that it appears that your emotions, and all your mental states for that matter, are created out of the same basic “ingredients” of the mind (for a more in-depth discussion, see here). These ingredients probably serve very basic functions such as activating your body for engaging in actions, representing your body changes as feelings, representing your past experiences in order to make meaning of the present, processing visual and auditory information from the world, and directing your attention to changes outside in the world or inside your body. The idea that your mental states are the complex products of basic “ingredients” is fundamentally different from the idea that each brain region serves its own special function for its own specific mental state. This new view also begins to chart a different path forward for understanding mental illness—a person with anxiety might not have something amiss with their “fear center,” but might instead have something wrong with a system that activates the body or a system that shifts attention (or both). We’re still just scratching the surface of how your brain creates emotions and fMRI offers only a single lens, but it’s already telling us important new things about how our brain creates our mental lives.

 

Photo credit: https://en.wikipedia.org/wiki/Biological_neural_network licensed for use