BERNADETTE RESHA: I like to do landscapes. So I like summer and fall that brings out the colors that I love.

NARRATOR: Burnadette Resha is an artist. She also has Down Syndrome, a genetic disorder resulting from an extra chromosome that can cause intellectual disability. But what exactly is intelligence?

NADEEN KAUFMAN: I would say intelligence is the ability to solve new problems, the most efficient way.

NARRATOR: Many people think of intelligence as book smarts— the skills that help us do well in school. But there are many types of intelligence. Bernadette is clearly gifted in other ways.

When did you first get interested in art work and expressing yourself?

BERNADETTE RESHA: All of my life.

ALAN S. KAUFMAN: I think that too often intelligence is viewed as an IQ, as one number. That is the opposite of how we define intelligence. We have different skills. And because our culture is so oriented toward verbal and academic skills, we tend to under-appreciate those children who have really good visual-spatial or artistic skills.

NARRATOR: In 1988, psychologist Robert Sternberg proposed that adults use three fundamental types of intelligence to varying degrees— analytic, practical, and creative intelligence. Other researchers such as Howard Gardner have described multiple intelligences, ranging from musical to interpersonal intelligence. Intelligence comes from a mix of nature and nurture. But the balance between those two things is unclear.

ALAN S. KAUFMAN: If your parents are more intelligent, yes, you would get their DNA. But those parents often value education and will value museum trips and other cultural endeavors. So therefore it's really hard to know what comes from where.

NARRATOR: Intelligence tests measure an individual's performance in certain key cognitive areas against the performance of others the same age to find a global score of intellectual ability, or IQ score. IQ scores fall into a bell-shaped curve. Roughly half the population falls in the average range. Scores in the below average range may lead to a diagnosis of intellectual disability. Intelligence tests have changed over the years, away from a single IQ score toward multiple measures of IQ as a way to address the perceived biases in testing.

ALAN S. KAUFMAN: There was this huge gap between what intelligence tests were measuring and what theories of intelligence were saying intelligence was.

We started looking for tasks that didn't show ethnic differences across countries, across cultures, across subcultures. It's not perfect. Children with socio-economic advantages will also have advantages on intelligence tests. But we do our best to be as fair as possible.

NARRATOR: It's also important to remember that one of the main goals of intelligence testing is to isolate individuals who may need help.

ALAN S. KAUFMAN: IQ tests are important so we know the child's strengths and weaknesses, so we can pick an intervention that should work.

NARRATOR: While intelligence is clearly important, other factors such as grit and determination may be just as crucial for achieving success.

NADEEN KAUFMAN: There's so many other aspects of success such as motivation. A person who is motivated to do well in anything will be more likely to succeed than one who doesn't. And that is not measured by an intelligence test.

Bernadette's tenacity and creative spirit stand out. With the help of friends and family, Bernadette travels the country to sell her artwork, giving her valuable exposure to other people and places.

BERNADETTE RESHA: I did get ideas outside of the world. Art is like an inspiration. I can paint and create and express myself. I love my life.

[LAUGHTER]