The world needs hot coffee.

You walked into the psychology department of Yale University because you saw an ad a week ago that they were looking for subjects-- not only to participate in scientific experiments in person, but also to get paid-- so you came. The receptionist at the front desk is going to take you to the lab on the fourth floor by elevator. He planned to record your basic information as he went upstairs, but he had a cup of hot coffee, a record board and two textbooks in his hand, so he asked you to help him with the hot coffee.

When you come to the lab, the experimenter gives you a description of a person: Mr. An is smart, smart, frugal, decisive, practical and cautious. Then give you a questionnaire and ask you to rate Mr. An in ten aspects, five of which are related to Mr. A's enthusiasm. For example, is Mr. A happy or unhappy, generous or stingy, gregarious or antisocial, and so on. On the whole, you are more likely to think that Mr. An is a passionate person, although you have no idea who this person is, but you trust your intuition. After that, they also ask you to rate all aspects of a car. You're not surprised to do these questionnaires, because you knew before you came here that it was an experiment on personal perception and consumption. This is the end of the experiment.

At this time, you may have forgotten to bring someone a cup of hot coffee, let alone think that this cup of hot coffee has affected your judgment of Mr. A. Then let time be turned back. When you come to the psychology building, what you bring to the reception is not hot coffee, but iced coffee. Everything else is the same as last time. Then you will be surprised to find that this time Mr. An in your heart is a relatively indifferent person.

Later, you were told that you were actually taking part in a physical and psychological temperature experiment by professors Lawrence E. Williams and John A. Bargh, while the rest was just a cover. They find that physical and psychological feelings are often thought-through. The concepts of cold and heat can be used not only to describe temperature, but also to describe people's personality and feelings about certain situations. Linguists have found that people often use the external world to describe the inner spiritual world. People can feel whether others are warm-hearted or cold-blooded, call a comfortable environment "warm" and call jokes that do not have a strong reaction immediately as "cold jokes". More people are called "lively", while fewer people are called "deserted".

In the eyes of children, there are two kinds of people in the world: good people and bad people. When people grow up, they are more likely to judge people by two other indicators: enthusiasm and ability. For the latter, we judge by objective indicators, while for the former, it is often done automatically by people inadvertently. Because this automatic process is faster and more efficient, whether in the jungles where ancestors lived or in cities where modern people live, quickly distinguishing between the "friend and foe" camp is a top priority. The next step is to decide whether to approach or stay away.

So why does hot coffee increase positive judgment? In fact, it is human nature to yearn for warmth. Warmth can bring people sense of security. Even monkeys, in the famous rhesus monkey experiment, always snuggled up to the furry fake monkey instead of the wire monkey that gave him milk. The warmth of hot coffee evokes warm memories of childhood, which are always accompanied by trust, protection and nutrition, all of which allow people to look at things around them in a more positive way.

This has also been confirmed in brain studies, where neurobiological studies of attachment have found a link between babies' feelings of touch temperature and their feelings of psychological warmth and trust. Recent studies have also found that both physical and psychological temperature signals are processed in the same region of the brain.

Physical warmth can not only change our view of the world, but also affect our own behavior. In another experiment by professors Lawrence E. Williams and John A. Bargh, they asked subjects to use ice bags (ice pad) or hot pad products in the name of rating the effects of these products. Then, in order to thank them, let them choose gifts: they can choose a drink of their own, or they can choose coupons to give to their friends. Subjects who used ice bags were less willing to give gifts to friends than those who used hand warmers.

I used to hear people say, "No one hurts when your hands are cold." In fact, whether the hands are cold or not has little to do with the pain of others, but the lack of warmth in their own bodies may lead to psychological gloom and behavioral apathy. The incidence of depression is the highest in autumn and winter, and ordinary people sometimes have a little sad autumn thought, which may be related to the relatively low temperature at this time. So it seems that drinking a glass of hot milk and taking a hot bath before going to bed can really relieve insomnia, because the warmth it brings can reduce inner anxiety.

There is an old song called "the world needs warm-hearted heart". In fact, the world is not short of warm-hearted heart, everyone may see a warm world. It turns out that the cafe owner knows more about psychology. He wrote on the wall many years ago: the world is so lonely that it needs a cup of hot coffee.