Intellectual ability refers to the skills required to think critically, see connections between disciplines and problem solve in new or changing situations. Memory, creative problem solving and vocabulary also contribute to the level of an individual's intellectual ability. While scientists differ on one standard definition of intellectual ability, most agree that intellectual ability must include a high level of abstract reasoning and thinking skills, the ability to acquire knowledge and problem-solving abilities.

Genetic Correlations

Research indicates that intellectual ability is partially inheritable. A research team from the University of Edinburgh compared DNA from more than 3,500 people that took an intelligence test. The study concentrated on fluid and crystallized intelligence. The results showed that more than 40 percent of the differences in intelligence existed due to genetic variations. The remaining differences in intelligence resulted from environmental factors and genes that the researchers couldn't capture. Scientists at Kings College in London discovered a gene that appears linked to intellectual ability. Researchers discovered that individuals with a high-functioning NPTN gene tended to perform better on intelligence tests. Those with a high-functioning NPTN gene also showed evidence of a thicker cerebral cortex, a portion of the brain linked to intelligence.

Fluid and Crystallized Intelligence

The ability to apply creative, novel solutions to a given problem indicates a high level of intellectual ability. When presented with a difficult and new situation, someone with a high degree of intellectual ability shows a greater ability to understand the problem and comes up with adequate solutions. Scientists identify two types of intelligence -- fluid and crystallized intelligence. Fluid intelligence refers to the ability to solve novel problems and respond to situations. Crystallized intelligence relies upon experience, developed skills and previously learned knowledge to solve a problem. Both fluid and crystallized intelligence contribute to an individual's ability to solve problems.

Memory

The ability to recall and memorize information plays a role in intellectual ability. A good memory helps individuals solve problems more effectively, but stressful situations and lifestyle choices can also affect memory. Individuals can improve their memory to help boost certain aspects of intellectual ability. Specifically, increasing your ability to store information can increase your fluid intelligence. According to the National Institute of Health, working memory enables an individual to keep important thoughts in an easily accessible state and is correlated to fluid intelligence and scholastic ability.

Vocabulary

Vocabulary helps an individual articulate and formulate ideas. An advanced vocabulary can help individuals dissect words and understand new words they haven't yet learned. The Wechsler Abbreviated Scales of Intelligence test, designed to assess intellectual ability and perceptual organization uses vocabulary partially to determine levels of intellectual ability. Since vocabulary comes from a person's ability to absorb new words and learn new concepts, a large vocabulary indicates a high level of intellectual ability.