Intelligence
Intelligence can be defined as the ability to solve complex problems or make decisions with outcomes benefiting the actor and has evolved in lifeforms to adapt to diverse environments for their survival and reproduction. For animals, problem-solving and decision-making are functions of their nervous systems, including the brain, so intelligence is closely related to the nervous system.
Intelligence can be defined as a general mental ability for reasoning, problem-solving, and learning. Because of its general nature, intelligence integrates cognitive functions such as perception, attention, memory, language, or planning. Based on this definition, intelligence can be reliably measured by standardized tests with obtained scores predicting several broad social outcomes such as educational achievement, job performance, health, and longevity. A detailed understanding of the brain mechanisms underlying this general mental ability could provide significant individual and societal benefits. Structural and functional neuroimaging studies have generally supported a frontoparietal network relevant to intelligence. This same network has also been found to underlie cognitive functions related to perception, short-term memory storage, and language. The distributed nature of this network and its involvement in a wide range of cognitive functions fits well with the integrative nature of intelligence. A new key phase of research is beginning to investigate how functional networks relate to structural networks, with emphasis on how distributed brain areas communicate with each other.
Intelligence is hard to define and can mean different things to different people. Once we consider the origin and function of intelligence from an evolutionary perspective, however, a few important principles emerge. For example, different lifeforms can have very different types of intelligence because they have different evolutionary roots and have adapted to different environments. It is misleading and meaningless to try to order different animal species on a linear acumen scale, such as when trying to judge which dog breed is the smartest, or whether cats are smarter than dogs. It is more important to understand how a particular form of intelligence evolved for each species and how this is reflected in their anatomy and physiology.
Various definitions of intelligence tend to converge around similar notions designed to capture the essence of this psychological factor. Jensen notes Carl Bereiter’s definition of intelligence: “what you use when you don’t know what to do”. After their extensive survey, Snyderman and Rothman7 underscored reasoning, problem-solving, and learning as crucial for intelligence. The “mainstream science on intelligence” report coordinated by Gottfredson8 highlights reasoning, planning, solving problems, thinking abstractly, comprehending complex ideas, learning quickly, and learning from experience. The American Psychological Association (APA) report on intelligence acknowledges that “individuals differ from one another in their ability to understand complex ideas, to adapt effectively to the environment, to learn from experience, to engage in various forms of reasoning, to overcome obstacles by taking thought”.
In a book, Birth of Intelligence (Oxford University Press, 2020), Lee traces the development of the brain and intelligence from self-replicating RNA to different animal species, humans, and even computers to address fundamental questions on the origins, development, and limitations of intelligence.
Any cognitive ability refers to variations in performance on some defined class of mental or cognitive tasks. Abilities reflect observable differences in individuals’ performance on certain tests or tasks. However, this performance involves the synthesis of a variety of abilities: “spatial ability,” for instance, can be regarded as an inexact concept that has no formal scientific meaning unless it refers to the structure of abilities that compose it. The problem of defining (and measuring) acumen is the problem of defining the constructs that underlie it and of specifying its structure.
IQ tests are interpreted as measures of general intelligence or g-which is construed as a heritable component of the commonality among measures of intellect that relates to the acquisition of knowledge. Intelligence changes over life-span-it with age and the IQ phenotype are more congruent with the genotype. Intelligence is influenced by cohort-specific exposures and requires exposure to formal education for its development. It is not easily changed and intelligence influences educational performance and occupational status.
The relation between intelligence quotient (IQ) and cognitive control skills is well established (Blair, 2006; Shamosh and Gray, 2008). The IQ is commonly divided into two factors: fluid and crystallized intelligence. Fluid intelligence refers to the capacity to solve and think logically about novel problems. It is independent of the acquired knowledge. It is measured by a non-verbal test that requires abstract reasoning, such as a Matrices test. These tests are designed to reduce the influence of culture, educational level and verbal comprehension. On the other hand, crystallized intelligence depends on experience and knowledge and it could be defined as the ability to use these factors. Generally, Vocabulary and Verbal tests are used as a measure of this aspect of acumen. Two important cognitive control abilities are filtering out interfering information and controlling impulsiveness. Interference suppression, i.e., filtering out interfering information, is a process that requires sustained attention to process relevant information and ignore irrelevant information. Furthermore, impulsivity could be considered as the consequence of dysfunctional inhibitory processes and strong impulses (premature execution of the response) and is modulated by dispositional and situational variables.
Human acumen is, mental quality that consists of the ability to learn from experience, adapt to new situations, understand and handle abstract concepts, and use knowledge to manipulate one’s environment. Theories of intelligence, as is the case with most scientific theories, have evolved through a succession of models. Four of the most influential paradigms have been psychological measurement, also known as psychometrics; cognitive psychology, which concerns itself with the processes by which the mind functions; cognitivism and contextualism, a combined approach that studies the interaction between the environment and mental processes; and biological science, which considers the neural bases of intelligence. What follows is a discussion of developments within these four areas.
Humans perceive the environment, attend to relevant stimuli, memorize episodic and semantic information, communicate, and so forth. However, these activities must be integrated in some way for (i) adapting our behaviour to the environment; (ii) selecting the most appropriate contexts; or (iii) changing the world when adaptation and selection are not an option.10 In our view, the integration of cognitive functions and abilities is dependent on the very general mental ability we call “general intelligence” or g for short. This integration is consistent with g as ability or as an emergent property of the brain.
“There is no longer any doubt that a larger brain predicts greater acumen. Several research teams, using differing scan protocols, populations, and cognitive measures, have all shown that IQ and brain volume correlate at about the 0.40 level replication of this effect is no longer required. What is required now is a more fine-grained analysis of why it is that a larger brain predicts greater intelligence, and what it is about acumen that is most directly related to brain volume”.
It is well-known that IQ, both fluid and crystallized intelligence is positively associated with some cognitive control processes. The interference tasks require similar processes to be solved as those involved in the Matrices test of intelligence (fluid intelligence). Both tasks require processes such as representing information, attending to relevant information and inhibiting premature responses. Moreover, resolving interference tasks not only requires one to solve and think logically but also is an important ability to use previous experience and knowledge. The relation between IQ and cognitive control abilities could be suggested that when resolving interference tasks, it is important to combine abstract reasoning (Matrices) and learned knowledge (Vocabulary). The association between IQ and cognitive control processes could be explained by assuming that crystallized intelligence may partially depend on fluid intelligence, that is, a combination of both bits of intelligence is important to resolve interference. However, the relation between impulsivity and IQ is more divergent. While some studies show a negative relation between impulsivity and IQ, others show that impulsivity is relatively independent of IQ.
