Although intelligence is difficult to measure in an animal that cannot take IQ tests as humans can, one measure of intelligence is the degree to which the cerebral cortex of the brain is folded. The dolphin's cerebrum contains a complex of tissue folded to a similar degree as that of the human brain. Also, its brain–to–body mass ratio is quite similar to that of the human, another potential indicator of intelligence. The dolphin's brain–to–body mass ratio is greater than most other mammals.

It is thought that the dolphin requires a larger brain (for its body size) to learn to adapt to different environments, learn a variety of feeding strategies, and even learn to interact with man. But scientists believe the major reason for such a large brain is to process information from the dolphin's complex echolocation, or biosonar system. Dolphins show the ability to learn rapidly and to learn about many things. They can remember events and learn concepts, changing their behavior as a result of previous experience. They can understand symbolic (sign) language.