As promised in my first post, I wanted to discuss the notions of crystallized intelligence, fluid intelligence and heritability to make more sense of the IQ scores that we use in our arguments. I decided to make short and to expand myself more in the comment section.
Crystallized intelligence is the ability to use skills, knowledge, and experience. It does not equate to memory, but it does rely on accessing information from long-term memory. Crystallized intelligence is one’s lifetime of intellectual achievement, as demonstrated largely through one’s vocabulary and general knowledge. This improves somewhat with age, as experiences tend to expand one’s knowledge.
The terms are somewhat misleading because one is not a “crystallized” form of the other. Rather, they are believed to be separate neural and mental systems. Crystallized intelligence is indicated by a person’s depth and breadth of general knowledge, vocabulary, and the ability to reason using words and numbers. It is the product of educational and cultural experience in interaction with fluid intelligence.
Crystallized intelligence is the most visible part of intelligence, it is reflected by scholastic achievement, wisdom or understanding of one’s subjective percieved reality. It could simply be summarized as the ability to learn from teachings and life experiences and to make a practical use of accumulated knowledge. On this variable, no ethnic, social or racial difference has been identified in terms of crude ability. However actual performance may be affected by different factors such as attitudes toward education, cultural views and practices and quality of teaching.
Crystallized intelligence impacts fluid intelligence by managing what a person learns from exposure to an environment or lifestyle that requires increased use of rational reasoning. Crystallized intelligence has experienced no change throughout the history of psychometric testing and it can be thought as a relatively fixed human-specific ability comparable to our senses such as sight and taste. On the other hand, fluid intelligence has made gains in the industrialized world that mirrored the diminishing influence of religion, superstition, biased theories, stereotypes and other irrational logic systems as well as dogmatic teaching styles that promoted memorizing without understanding.
Fluid intelligence or fluid reasoning is the capacity to think logically and solve problems in novel situations, independent of acquired knowledge. It is the ability to analyze novel problems, identify patterns and relationships that underpin these problems and the extrapolation of these using logic. It is necessary for all logical problem solving, e.g., in scientific, mathematical, and technical problem solving. Fluid reasoning includes inductive reasoning and deductive reasoning
Fluid intelligence is the variable for which ethnic, racial and social differences have been observed throughout the history of cognitive testing. Considering that rational thinking is by itself a partly or totally acquired skill handled by crystallized intelligence, a variable for which no group difference in crude ability has been observed, the major issue faced by attempts to measure fluid intelligence is identifying the role played by acquired knowledge in test-taker’s performances and to distinguish it from crude fluid reasoning ability.
Early childhood, when little knowledge has yet been accumulated, seems to be the most relevant period in order to understand the genetic component of fluid intelligence. By this time, cognitive function is raw, instinctive and untamed by social and environmental awareness. Interestingly, it is during early childhood that heritability is at its lowest point, that between-group differences are at their narrowest and that Black children tend to outperform White children evolving in a very similar environment. However, heritability as well as the magnitude of ethnic, social and racial differences has been shown to increase with age.
To explain the increasing heritability of IQ with age, two different logics can result in two different conclusions:
- Increased age equals to an increased time of exposure to a similar environment.
- The unknown genes that affect IQ scores reach the peak of their expression in adulthood.
The first hypothesis can be validated if we are able to prove that each supplementary year in life is one more year of experience in a given environment that is shared with a biologic parent. One empirical example is the heritability of racism, very low in childhood, it increases as one evolves in a similar race-conscious environment as one’s parents. Language has a similar evolution, unpredictable infantile speech and teenage slang eventually turn to similar adult language patterns with social and ethnic specificities. Childhood dreams of becoming firefighter, astronaut, doctor or princess often vanish in a career that is more or less similar to that of parents in terms of SES and part of the Flynn effect may be attributed to the post-war era of massive inter-generational upward mobiliy trends observed in the industrialized world that have led children to deal more frequently with pressures to rational thinking than their parents.
The second hypothesis can be validated if we find the involved genes and discover that they have the property of expressing themselves with more strength during adulthood. I don’t personally know any polygenic trait that has this kind of development, identical twins tend to be identical at any age except for behavior that has higher variation and needs to be proven to equalize independantly of social and cultural factors as age increases.
The two hypotheses make sense in their own respective paradigms which are handled by crytallized intelligence leading people to perceive different notions of logic depending on their culture and life experience. The first proposition is linked to a logic system in which facts need a direct proof to be considered true. The second one makes sense in a paradigm in which direct factual proofs are not necessary to establish the irrefutable truth. Though none of the two propositions must be considered stupid or illogic as if it was self-contradicting, the second one would fail on most tests of fluid intelligence which are designed with the rational idea that facts must be demonstrated by the most direct evidence in order to be considered true.
To make a short conclusion:
Crystallized intelligence is our ability to make use of what we know or believe whereas fluid intelligence controls the way we deal with the unknown. Crystallized stupidity is when one makes an error, acknowledges it as an error and willfully repeats it. Crystallized intelligence obviously varies greatly between individuals and no genetic cause of this variation must be excluded but no difference has ever been recorded between groups. Fluid stupidity does not exist however, every one makes use of a particular logic when trying to solve a problem. How coherent this logic is depends on the rational quality of one’s accumulated knowledge. Thus, IQ tests must be interpreted in terms of learnt rationality instead of crude intelligence.
