Here are the nation's top thinkers on how to be happy, improve our sex lives, and more

Dr Helen FisherGetty ImagesHelen Fisher, biological anthropologist

Most of us have no idea why we react certain ways or make specific decisions.

But five psychologists are up for the task of figuring out what it is that makes us human.

We recently compiled a list of 50 scientists doing amazing work around the world. Here are the psychologists whose work is redefining the way we look at what goes on inside our heads.

Scott Barry Kaufman is redefining the way we measure human intelligence.

As humans we like to think of ourselves as the most intelligent animals on the planet. But how do you measure human intelligence? Traditionally, tests focus on how well we use logic. However, that's just one of many facets that describe intelligence, according to Scott Barry Kaufman, who is redefining the way we think of what being intelligent means with his dual-process theory of human intelligence.

Kaufman argues that a person's level of passion, persistence, and ability to set and meet personal goals are as equally important as logic and reasoning when it comes to measuring human intelligence. Kaufman has published five books on his theories about what defines human intelligence. He writes a regular column for Scientific American called Beautiful Minds and hosts The Psychology Podcast.

Kaufman is the scientific director of the Imagination Institute at the University of Pennsylvania's Positive Psychology Center.

Sonja Lyubomirsky is teaching us how to be happy.

You are in control of about 40% of your own happiness, according to Sonja Lyubomirsky. The other 60% comes from a mixture of genetics and your environment.

Lyubomirsky is an expert on human happiness and author of the book 'The How of Happiness,' in which she explains science-backed ways humans can increase their happiness. In addition to exploring how to be happier, Lyubomirsky studies whether happiness is a good thing and what things make people most happy. So if you're feeling low, crack open her book. After a few pages you might just find a way to feel better.

Lyubomirsky is a professor of psychology at the University of California at Riverside.

Norman Doidge has developed a brand new field of science that revolutionizes the way we think about our brains.

If you're looking for the next big thing in neuroscience, the best person to speak to is Norman Doidge, a physician, psychiatrist, and writer. Doidge pioneered a new field of science called neuroplasticity, wherein he says the human brain is capable of repairing itself from damage or injury much better than previously thought.

Doidge has written two New York Times best-sellers on his theory, 'The Brain That Changes Itself' (2007) and 'The Brain's Way Of Healing' (2015) where he argues that the human brain can rewire itself -- change the neuropathways by which it processes information -- and thereby heal itself from learning disorders or even some of the physical consequences that result from a stroke. The way this rewiring works is through a series of mental exercises that target the impaired part of the brain. Through these incremental exercises that grow increasingly more difficult, the brain can change and heal.

Doidge is faculty member at the University of Toronto's department of psychiatry.

Helen Fisher is an expert on love, relationships, and sex.

You can call Helen Fisher a love expert -- she's spent over 30 years researching human emotions and romantic relationships. Fisher's research explores what happens when two people fall in love and how factors such as sex, lust, and marriage alter brain processes. For example, in one paper she explored the long-term use of antidepressants, finding that in some people they can halt the brain's ability to fall in love.

Fisher's chronicled her research in several books, including 'Why Him? Why Her?: How to Find and Keep Lasting Love' and 'Why We Love: The Nature and Chemistry of Romantic Love' and has shared her findings a popular TED Talk about why people cheat. Fisher puts her vast relationship knowledge to use in a practical way -- she's the chief scientific adviser to

Fisher is a biological anthropologist at Rutgers University.

Jennifer Eberhardt is improving race relations between police and the communities they serve.

Social psychologist Jennifer Eberhardt studies the ways people judge and profile others based on race, largely focusing on crime.

At a time when these biases are extremely prevalent, the findings prove particularly poignant. Eberhardt, a 2014 MacArthur fellow, works with law-enforcement officials to apply her findings, improving police policies and helping to build trust within the communities they serve.

Eberhardt is an associate professor at Stanford University in the department of psychology.

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