Welcome to Your Brain (23 page)

guaranteed) that there’s some relationship between them—but you still can’t tell what the

relationship is. For example, knowing that married people are happier on average than

single people doesn’t tell us whether your son would be happier if he got married, no

matter what you might personally believe. Being married could make people happier, or

being happy may simply make it easier to get married. Indeed, psychologists who measure

happiness in the same individuals through several years of their lives have found that both

these statements are true. Happier people are more likely to get married; that, in turn, makes

them happier still. Not all happiness research is correlational, but when we interpret

studies of this type, we need to remember that a correlation between two things can’t tell us

what we would most want to know: which thing causes the other, or if there is a third,

unknown cause of both things.

Another point to keep in mind is that, as with most psychological research, the answer

you get depends greatly on how you ask the question. For instance, when women were

asked to list the activities that they particularly enjoyed overall, “spending time with my

kids” topped the list. In contrast, when other researchers asked women to describe how

they felt during each of their activities the previous day, the average positive rating given to

interacting with children indicated that this activity is roughly as rewarding as doing

housework or answering e-mail. This finding suggests that women find their children more

rewarding in theory than in practice, at least on a moment-to-moment basis.

In its strongest form, the adaptation idea suggests that all efforts to increase happiness in an

individual or society are futile and that people’s life circumstances have no long-term influence on

their happiness. This would be pretty surprising and almost certainly isn’t correct. Indeed, some

circumstances are reliably associated with unhappiness, including chronic pain or having to commute

a long way to work.

The life events most likely to have a lasting negative influence on people’s happiness include the

death of a spouse, divorce, disability, and unemployment. In all these circumstances, people still

adapt—their happiness is much more strongly affected right after the event and then moves back

toward the baseline—but the adaptation is not complete. Even eight years after the death of a spouse,

surviving partners remain less happy than they were when their spouse was alive. Deliberate attempts

to increase happiness have also had some lasting success, though these interventions seem to be most

effective if they are repeated frequently (see
Practical tip: How to increase your happiness
).

When psychologists follow the same people over time, most of them report fairly stable

happiness. In one study of Germans over a seventeen-year period, the happiness of only 24 percent of

the participants changed significantly from the start to the end of the study, and only 9 percent changed

a lot. All individual circumstances—marriage, health, income, and so on—taken together account for

only 20 percent of the differences in happiness from one individual to another in the U.S., while

genetic factors account for about 50 percent of the differences. Identical twins reared apart (usually

because they were adopted separately) are much more similar to each other in their adult happiness

than fraternal twins who are reared apart, and about as similar in happiness as identical twins reared

together. (The mysterious remaining 30 percent includes measurement errors, such as the differences

between individuals in defining survey responses like “mostly satisfied.”)

In general, the brain seems to respond more strongly to changes than to persistent conditions, right

down to the level of single cells. Neurons also show adaptation (though they typically do it in less

than a second, not months). Adaptation is efficient because most of the information in the world is

stable, while most of the action that is important to your brain lies in the part of the world that is

changing—objects that are moving, your mate’s new facial expression, or an unexpected source of

food. If the brain can cheat by devoting its limited resources to representing the information that is

new, it may be able to more effectively help you respond to the world.

Neurons in several brain areas respond specifically to events that are “rewarding.” A reward

makes you more likely to repeat the behavior that led to the reward; examples are food, water, sex,

and a variety of more complicated things like positive social interactions. In people, we know

rewards are associated with a subjective sense of pleasure, and people, like other animals, are

willing to work for them (as well as for human-specific rewards like money). However,

opportunities to record the responses of individual neurons in humans are rare, so studies of this sort

are typically done with rodents or monkeys.

Practical tip: How to increase your happiness

Happiness is a moving target. Because of adaptation, frequent small positive events

have a greater cumulative impact than occasional large positive events. Similarly, the

elimination of daily irritants like commuting is likely to provide a substantial improvement

in happiness. It’s hard to believe that it would make you happier to spend fifteen minutes

every evening for the rest of your life having a relaxed drink with a sympathetic friend than

it would to win the lottery, but it’s almost certainly true.

What makes people happy day to day? Women who were asked to recall their emotions

at the end of each day rated having sex as the most rewarding activity, considerably ahead

of the runner-up, socializing with friends. Indeed, more sex correlates with more happiness

—and unlike money, the happiness-producing effects of sex do not diminish once you have

enough of it. How well people slept the previous night has a stronger correlation with their

enjoyment of the day than their household income. Setting realistic goals and achieving

them is also associated with happiness for most people. You probably don’t need to worry

too much about varying your daily routine, as people who stick with their old favorites are

happier than people who seek variety for its own sake.

The study of happiness is still in its infancy, but a few researchers have shown that

behavioral exercises can increase happiness. The exercises are most effective if you do

them consistently. Here are a few of the exercises that work:

• Focus on positive events.
Every evening for a month, write down three good things

that happened that day and explain what caused each of them. This exercise increased

happiness and reduced symptoms of mild depression within a few weeks, and the effects

lasted for six months, with particularly good outcomes for people who continued to do the

exercise.

• Practice using your character strengths.
You can find out what your strengths are by

going to
http://www.authentichappiness.org
and taking the VIA Signature Strengths

questionnaire. (The Web site is run by Martin Seligman, a well-known positive

psychologist at the University of Pennsylvania. You’ll need to register for access to the site,

but the tests are free.) Once you know your top five strengths, make a point of using one of

them in a new way every day for a week. This exercise and the previous one grew out of

Seligman’s research, as described in his book,
Authentic Happiness
.

• Remember to be grateful.
Every day write down five things that you are thankful for.

People who did this exercise for several weeks had more positive feelings and fewer

negative feelings than people who did a placebo exercise. However, we do not know

whether the effects are long-lasting, as the subjects were only followed for a month.

Scientists can distinguish between neurons that respond to rewards and neurons that respond to

other aspects of a stimulus, like taste. The reward neurons are those that stop responding when the

animal no longer wants the reward, like when a rat is no longer interested in a food because it has had

enough to eat (though presumably the food still tastes the same). These neurons are found in brain

regions like the orbitofrontal cortex, striatum, and amygdala, and they often respond not only to the

existence of a rewarding stimulus, but also to some particular characteristic of the reward. For

instance, one neuron might respond to one type of food but not another, or to a small reward but not a

large reward. Although different neurons within a given brain area have different preferences, the

same set of brain areas is active when the animal receives a lot of different rewards, from food to sex

to the opportunity to spend time with its mate.

Some such neurons release the neurotransmitter dopamine. These neurons are located in the

substantia nigra and the ventral tegmental area of the midbrain, and they project their axons to a

variety of other brain regions that contain reward-responsive neurons, including those discussed

above. These neurons seem to be specifically involved in reward prediction. Dopamine neurons are

activated by unexpected rewards. For instance, experimenters taught rats that they could press a lever

and get a reward—but only after a light was on. During the early stages of training, neurons were

active when the food arrived. Later on, after the animals knew the task, the dopamine neurons began

to fire as soon as the light went on—when the animal first knew it was going to get some food—and

they were inhibited when the food failed to show up on schedule. When enough disappointments

happened repeatedly, the neurons stopped firing in response to the light, and the animals stopped

pressing the lever. In a variety of situations, then, these neurons appear to tell animals about which

features of the environment predict when they will receive a reward.

What do dopamine or reward-responsive neurons have to do with happiness? We don’t know

how to define happiness in rats (it’s hard enough to define in people), but it does look as though

dopamine helps rats—and people—to choose behaviors that lead to positive outcomes. Evidence that

signaling reward is one of dopamine’s functions in people comes from Parkinson’s disease, a

movement disorder that involves the progressive death of dopamine-making neurons serving multiple

functions. In addition to their motor problems, Parkinson’s patients have difficulty learning through

trial and error. When medication makes their dopamine levels high, Parkinson’s patients learn more

about responses that are paired with rewards. In contrast, when patients are not taking medication,

and their dopamine levels are low, they learn more easily about responses that are paired with

negative consequences. These results suggest that dopamine is involved in learning to choose

behaviors that lead to positive outcomes, which sounds like a key ingredient in happiness to us.

Success is getting what you want. Happiness is wanting what you get.

—Unknown

Chapter 19

What’s It Like in There? Personality

It’s never pleasant to be disliked by someone you work with, especially when that someone plays

anonymous practical jokes. However, as Shelley found, it can be a little less unpleasant when that

someone is six inches long and has no bones—indeed, has no hard parts except for a beak.

Shelley spent one summer at the Marine Biological Laboratory, a research center on Cape Cod,

Massachusetts, working with cuttlefish. Cuttlefish are members of the cephalopod family, a strange

group of big-brained, big-eyed, multilimbed marine animals; their close relatives include octopuses

and squid. That summer, Shelley spent her days in a small room with a cuttlefish in a tank next to her

while she prepared behavioral tests for the animal. One day she felt something wet on her backside.

She turned around, and saw nothing—just a cuttlefish in the tank. She assumed it was just a random

splash from the aquarium pump. As it turns out, it was a pump—just not a mechanical one. She was

splashed again several times before she realized that the water was coming from the cuttlefish itself.

All cuttlefish have a siphon that they use to send water in specific directions. This particular

cuttlefish was using its siphon on Shelley, but only when her back was turned. Somehow, it’s hard to

shake the sense that Shelley was the victim of a repeated expression of dislike by her crotchety

experimental subject.

It’s clear that individual animals have distinctive personalities, and that personality is at least

partially inherited. Dog fanciers will gladly explain in great detail the quirks of different breeds.

Pomeranians are high-strung; pugs, agreeable and unaggressive. One can see the whole range of

behavior on display on any sunny day in a dog park. Personality also varies among species: we

present exhibit A, the notable absence of cat parks.

Most of our interest in animal personality stems from our encounters with companion animals,

such as dogs and cats. But ethologists (scientists who study animal behavior) examine individual

personality and temperament in many species, from dairy goats and horses to guppies and spiders.