Fluid intelligence is the ability to solve novel reasoning problems and is correlated with a number of important skills such as comprehension, problem-solving, and learning.
[8] Fluid intelligence (gf) involved basic processes of reasoning and other mental activities that depend only minimally on prior learning (such as formal and informal education) and acculturation.
[9] Examples of tasks that measure crystallized intelligence are vocabulary, general information, abstract word analogies, and the mechanics of language.
[11][12] Fluid ability and Piaget's operative intelligence both concern logical thinking and the "eduction of relations" (an expression Cattell used to refer to the inferring of relationships).
Like fluid ability's relation to crystallized intelligence, Piaget's operativity is considered to be prior to, and ultimately provides the foundation for, everyday learning.
[18] Individuals have to apply concepts by inferring the underlying "rules" for solving visual puzzles that are presented with increasing levels of difficulty.
As the level of difficulty increases, individuals have to identify a key difference (or the "rule") for solving puzzles involving one-to-one comparisons.
The most difficult items require fluid transformations and cognitive shifting between the various types of concept puzzles that the examinee had worked with previously.
[18] In the Analysis–Synthesis test, the individual has to learn and orally state the solutions to incomplete logic puzzles that mimic a miniature mathematics system.
Increasingly difficult items involve a mix of puzzles that requires fluid shifts in deduction, logic, and inference.
[17] The Wechsler Intelligence Scales for Children, Fourth Edition (WISC-IV)[19] is used to have an overall measure in cognitive ability with five primary indexing scores.
This task assesses the child's ability to discover the underlying characteristic (e.g., rule, concept, trend, class membership) that governs a set of materials.
Since Matrix Reasoning and Picture Concepts involve the use of visual stimuli and do not require expressive language, they have been considered to be non-verbal tests of gf.
[25][26] Crystallized intelligence typically increases gradually, stays relatively stable across most of adulthood, and then begins to decline after age 65.
[27] Working memory capacity is closely related to fluid intelligence, and has been proposed to account for individual differences in gf.
Crystallized intelligence appears to be a function of brain regions that involve the storage and usage of long-term memories, such as the hippocampus.
Some researchers, however, question whether the results of training interventions to enhance gf are long-lasting and transferable, especially when these techniques are used by healthy children and adults without cognitive deficiencies.
"[32] In a series of four individual experiments involving 70 participants (mean age of 25.6) from the University of Bern community, Jaeggi et al. found that, in comparison to a demographically matched control group, healthy young adults who practiced a demanding working memory task (dual n-back) approximately 25 minutes per day for between 8 and 19 days had significantly greater pre-to-posttest increases in their scores on a matrix test of fluid intelligence.