Most of us find human nature a facinating subject. Science does, too, and psychologists have come up with some very interesting discoveries in the what-makes-people-tick department.

To match your wits with the findings of the experts, check which of the following questions you believe true or false -- then read the answers.

1 -- You can increase your intelligence by associating with people who are smarter than you are.

2 -- Where romance is concerned, absence makes the heart grow fonder.

3 -- Happy people have the fewest automobile accidents.

4 -- People who think nobody likes them are usually right.

5 -- Time goes by faster when you are doing difficult work.

6 -- The smarter you are, the easier it is for you to remember things.

7 -- Take life easy and you'll live longer.

8 -- In most cases, a person's voice gives him away when he tells a lie.

9 -- Poor people worry more about money than those who have plenty of it.

10 -- Women worry more than men do.

The answers are boxed to the right.

What are people afraid of?

Rather surprisingly, not war and the Bomb. At the Illinois Institute of Technology psychologists made a careful study of the fears and anxieties of a representative cross-section of American businessmen. They found that they are subject to 10 chief fears:

1 -- Financial: 80 percent were afraid they were going to lose money or not make enough.

2 -- Job security: 74 percent worried about losing their jobs, as a result of shakeups, business falling off, interoffice politics or competition from younger men.

3 -- Health: 69 percent were worried about real or imaginary ailments.

4 -- Personal appearance: 59 percent were fearful that their dress and manner were handicapping their chances of success.

5 -- Politics: Apprehensions and anxieties in this area affected 56 percent of the businessmen polled, and centered around government trends, such as taxation.

6 -- Marital difficulties: 44 percent were worried by incompatability.

7 -- Lack of self-confidence: 40 percent feared they didn't have enough "on the ball."

8 -- Religious and philosophical convictions: 37 percent were worried over what to believe.

9 -- Sexual morality: 34 percent were subject to worries and conflicts arising from temptations and/or transgressions.

10 -- Trouble with relatives: Anxieties in this department affected 33 percent, and ranged from the fear that "my mother-in-law is going to drive me out of my mind," to how to get rid of the wife's brother before he wrecks the business.

1 -- False. In wide-scale studies conducted by Army psychologists, 400 trainees were separated into two groups: those whose IQ was average or below, and those who scored in the higher brackets. Men of lesser intelligence were then billeted with personnel of higher than average IQ for extended periods of time. Subsequent tests showed constant association with men of higher intelligence had no appreciable effect in increasing the IQ or general aptitude of the less-intelligent recruits. Conclusions of the investigators: Intelligence is something that doesn't rub off.

2 -- True for men, false for women. In studies conducted at the University of Redlands, psychological tests showed that where men are concerned, separation from their mate or sweetheart does tend to make the heart grow fonder; but women's affections are more likely to cool than grow warmer.

3 -- True. Psychological studies show that people who are happy and well-adjusted are the safest drivers, collect the fewest dented fenders, smashed radiators, and so on. For example, extensive studies conducted at the University of Western Ontario show conclusively that the motorist who has a happy outlook on life is far less subject to accidents than others.

4 -- True. University of London investigators made a study of this matter. Their findings: While unpopular people are particularly dense in sizing up the feelings of others about them, people who think nobody likes them are usually 100 percent correct.

5 -- True. Experiments at Duke University have shown that when you're doing work that is difficult and requires concentration, time appears to pass much more swiftly than when you are doing work that is easy for you.

6 -- False. University studies show that memory and intelligence are two distinct functions and that a man can be extremely intelligent and have a very poor memory -- and vice versa. When memory tests were given children in New York City schools, it was found that the scores made by the mentally retarded were as high or higher than those of average or above-average intelligence.

7 -- False. New York University studies have shown that people who take life the easiest -- who are the least active mentally and physically -- age the quickest and are at least resistent to disease. Research at other universities bears out these findings and shows conclusively that leading an active and busy life plays a vital part in longevity.

8 -- True. The odds are far better than even that you can tell when a person is lying just by listening to his voice. In psychological tests conducted at De Pauw University, an audience of men and women students was asked to listen to the voices of hidden speakers and try to determine when they lied and when they told the truth. Investigators then asked the hidden speakers such questions as "How old are you?" What do you weight?" "What color is your necktie?" and so on. They were instructed to answer some of the questions falsely and to lie in as plausible a manner as possible.

In the majority of cases, the listeners were able to judge correctly which of the statements were truthful and which were false.

9 -- False. Purdue University studies of persons invarious socioeconomic brackets show that the class which has the least money does the least worrying about it. Sociologists found that people in the lower-income brackets not only worry less about money, but worry less about most other things. They showed a marked inclination to live for today and let tomorrow take care of itself.

10 -- True. Psychologists at the University of Southern California, who made a wide-scale study of men and women from various walks of life, found that women are more given to worry and feelings of depression than are men. Other investigations have shown that women are not only subject to a greater variety of fears and phobias, but that their anxiety reactions are more intense.