Intelligence is often described as our ability to learn about our environment, learn from interactions with the environment, and understand this newly incorporated information (Intelligence, 2009). This ability is supported by neural networks within our brain composed of two major brain areas. Our ability to reason, plan, and organize is supported by our frontal lobe, while our ability to incorporate sensory information to inform our decisions is supported by our parietal lobes (Intelligence, 2009). Together, both of these systems help us to conduct spatial awareness, verbal, mathematical, and mental dexterity tasks, which are all measured by researchers in order to compute an intelligence quotient, or IQ, score. Researchers utilize these IQ scores as a way to operationalize and measure an individual’s intelligence level (Intelligence, 2009). There are many different types of intelligence that researchers focus on. Two of these intelligence types are fluid and crystalized intelligence.
Fluid intelligence can be described as our cognitive ability to perceptualize our individual representations of the environment, or our external world. This type of intelligence supports our ability to think logically, think abstractly, reason, and work our way through novel situations and new problems we may encounter in life (Salas, Escobar, & Huepe, 2021; Petrican, Graham, & Lawrence, 2021). This type of intelligence is believed to be supported by the same structures that support our ability to critically think and make goal-oriented decisions, our frontal lobe. Evidence for this can be seen in fMRI studies which reveal that when individuals are given tasks that require fluid intelligence, such as working through a puzzle, this area of the brain becomes highly active (Salas, Escobar, & Huepe, 2021). An example of a way in which researchers can test one’s fluid intelligence level can be observed by looking at the Ravens Progressive Matrices test, or RPM. In this test, individuals are given various types of patterns with individual pieces missing. From a pool of options, individuals are required to find a piece that would the most likely to be the missing puzzle piece (Petrican, Graham, & Lawrence, 2021).
On the other hand, crystalized intelligence is believed to be supported by our long-term memory systems. The reason for this is that crystalized intelligence is a measurement of our ability to store declarative information, or what we know about people, places, and things, and procedural information, or how to utilize this learned knowledge in order to do specific tasks (Salas, Escobar, & Huepe, 2021). This information is made up of all of the different concepts that a person has learned from their personal experience and from their academic life. For example, some researchers measure crystalized intelligence by looking at one’s vocabulary level, their ability to fluently incorporate words, and utilize mathematical knowledge (Salas, Escobar, & Huepe, 2021). An example of a test measuring one’s crystalized intelligence is a proverb comprehension test. In this type of test, a researcher may ask a participant to providing meanings of various proverbs utilized in their respective language (Petrican, Graham, & Lawrence, 2021). This type of intelligence is supported by many of the same structures utilized in long-term memory. For example, in order to access memory needed in crystalized intelligence tests, one would rely on brain systems including the basal ganglia, anterior temporal lobe, superior temporal sulcus, hippocampus, and the medial temporal lobe (Gazzaniga, Irvy, & Mangun, 2018).