OUR senses appear to
show us the world the way it truly is, but they are easily deceived. For
example, if you listen to a recorded symphony through stereo speakers that
are placed exactly right, the orchestra will sound like it’s inside your head.
Obviously that isn’t the case.
But suppose you
completely trusted your senses. You might find yourself asking well-meaning but
preposterous scientific questions like “Where in the brain is the woodwinds
section located?” A more reasonable approach is not to ask a where question
but a how question: How does the brain construct this
experience of hearing the orchestra in your head?
I have just set the
stage to dispel a major misconception about emotions. Most people, including
many scientists, believe that emotions are distinct, locatable entities inside
us — but they’re not. Searching for emotions in this form is as misguided as looking
for cerebral clarinets and oboes.
Of course, we experience anger, happiness, surprise and other emotions
as clear and identifiable states of being. This seems to imply that each
emotion has an underlying property or “essence” in the brain or body. Perhaps
an annoying co-worker triggers your “anger neurons,” so your blood pressurerises; you scowl, yell and feel
the heat of fury. Or the loss of a loved one triggers your “sadness neurons,”
so your stomach aches; you pout, feel despair and cry. Or an alarming news
story triggers your “fear neurons,” so your heart races; you freeze and feel a
flash of dread.
Such characteristics are thought to be the unique biological “fingerprints” of
each emotion. Scientists and technology companies spend enormous amounts of
time and money trying to locate these fingerprints. They hope someday to
identify your emotions from your facial muscle movements, your body changes and
your brain’s electrical signals.
Some scientific studies seem to support that such fingerprints exist. But many
of those studies disagree on what the fingerprints are, and a multitude of
other studies indicate there are no such fingerprints.
Let’s start with neuroscience. The Interdisciplinary Affective Science
Laboratory (which I direct) collectively analyzed brain-imaging studies
published from 1990 to 2011 that examined fear, sadness, anger, disgust and
happiness. We divided the human brain virtually into tiny cubes, like 3-D
pixels, and computed the probability that studies of each emotion found an
increase in activation in each cube.
Overall, we found that no brain region was dedicated to any single emotion. We
also found that every alleged “emotion” region of the brain increased its
activity during non emotional thoughts and perceptions as well.
The most well-known “emotion” region of the brain is the amygdala, a group of
nuclei found deep within the temporal lobes. Since 2009, at least 30 articles
in the popular press have claimed that fear is caused by neurons firing in the
amygdala. Yet only a quarter of the experiments that we analyzed showed an
increase in activity in the amygdala during the experience of fear. Indeed, it
has long been known that certain “fear” behaviors, such as fleeing, don’t
require the amygdala.
Other evidence against the amygdala-fear relationship comes from a pair of
identical twins,
known in the scientific literature as “BG” and “AM,” who both have a genetic
disease that obliterates the amygdala. BG has difficulty feeling fear in all
but the most extreme situations, but AM leads a normal emotional life.
If emotions are not distinct neural entities, perhaps they
have a distinct bodily pattern — heart rate, respiration,
perspiration, temperature and so on?
Again, the answer is no. My lab analyzed over 200 published studies, covering
nearly 22,000 test subjects, and found no consistent and specific fingerprints
in the body for any emotion. Instead, the body acts in diverse ways that are
tied to the situation. Even a rat facing a threat (say, the odor of a cat) will
flee, freeze or fight depending on its surrounding context.
The same goes for the human face. Many scientists assume that the face clearly
and reliably broadcasts emotion (scowling in anger, pouting in sadness,
widening the eyes in fear, wrinkling the nose in disgust). But a growing body of evidence suggests that
this is not the case. When we place electrodes on a human face and actually
measure muscle movements during anger, for example, we find that people make a
wide variety of movements, not just the stereotypical scowl.
CHARLES DARWIN famously vanquished the notion of essences in biology. He
observed that a species is not a single type of being with a fixed set of
attributes, but rather a population of richly varied individuals, each of which
is better or worse suited to its environment.
Analogously, emotion words like “anger,” “happiness” and “fear” each name a
population of diverse biological states that vary depending on the context.
When you’re angry with your co-worker, sometimes your heart rate will increase,
other times it will decrease and still other times it will stay the same. You
might scowl, or you might smile as you plot your revenge. You might shout or be
silent. Variation is the norm.
This insight is not just academic. When medical researchers ask, “What is the
link between anger and cancer?” as if there is a single thing called
“anger” in the body, they are in the grip of this error. When airport
securityofficers are trained on the assumption that facial and body
movements are reliable indicators of innermost feelings, taxpayers’ money is
wasted.
The ease with which we experience emotions, and the effortlessness with which
we see emotions in others, doesn’t mean that each emotion has a distinct
pattern in the face, body or brain. Instead of asking where emotions are or
what bodily patterns define them, we would do better to abandon such
essentialism and ask the more revealing question, “How does the brain construct
these incredible experiences?”
Lisa Feldman Barrett is a professor of
psychology at Northeastern University and the author of the forthcoming book
“How Emotions Are Made: The New Science of the Mind and Brain.”
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