The "Flynn effect" describes the increase in IQ scores that has been observed over the past century. On the other hand, the "Zeigarnik effect" is the tendency to remember unfinished tasks better than completed ones. The "Hawthorne effect" is the change in people's behaviors while they are being observed, and can occur in research subjects. Last, the "Cattell-Horn-Carroll theory" or CHC theory is the most supported intelligence theory, and states that intelligence includes three strata: general ability or "g," broad abilities, and several narrow abilities.

Howard Gardner is the father of the theory of Multiple Intelligences, which divides intellectual intelligence into seven different modalities (music, logical/mathematical, bodily/kinesthetic, visual/spatial, interpersonal, intrapersonal, linguistic).

Fluid intelligence involves the ability to reason and solve novel problems. The example of Bob solving an unfamiliar math problem is the only example that involves a novel situation. Bob being able to recite the former presidents and solve a math problem using familiar formulas are examples of crystallized intelligence (Gc), which refers to stored knowledge. Bob remembering how to ride a bike does not fit into Gc and Gf theory, but rather is an example of procedural/implicit memory.