Definition of General Intelligence & 5 Factors of IQ
3 dimensions of IQ
Our general intelligence (G) can be understood in terms of 3 underlying dimensions, made up of 5 factors:
(1) our knowledge base (crystallized intelligence)
(2) our thinking skills (fluid intelligence, visual intelligence)
(3) our cognitive efficiency or ‘brain power’ (processing speed, working memory/short-term memory)
General intelligence (G) – the ‘G’ factor
A person’s general intelligence is their ability to grasp situations, reason, problem solve and act efficiently and effectively in a purposeful way.
Definition of intelligence
David Wechsler – the creator of the most widely used psychometric IQ test, the WAIS – defined intelligence as:
the global capacity of the individual to act purposefully, to think rationally and to deal effectively with his environments.
While people have different cognitive strengths and weaknesses, psychologists have found that there is a common component called ‘general intelligence’ or ‘G‘. Individuals differ in their ‘G Factor’ & valid IQ tests give a good measure of those individual differences.
IQ tests are widely used in our society. Universities use IQ tests (e.g. SAT) to select students, companies use IQ tests (job aptitude tests) to screen applicants, and high IQ societies such as Mensa use IQ test scores as membership criteria. IQ scores have a distribution that looks like a bell curve.
IQ tests are designed so that the average IQ score is 100. In this graph, you can see that 68% of the population has an IQ score between 85 and 115. Around 2% of the population has an IQ greater than 130 which is a ‘very superior’ intelligence or ‘gifted’ intelligence. This is the IQ needed to become a member of Mensa. An IQ of 115 or more is considered a high IQ. Here is a table for what IQ scores mean:
Crystallized (verbal) intelligence (Gc)
Crystallized intelligence can be thought of as our knowledge bank – the product of what we invest our fluid intelligence into learning and knowing about. It is our crystallized knowledge – not our fluid reasoning and analysis.
Definition of Crystallized Intelligence (Gc)
Crystallized intelligence (Gc) is defined as:
Gc is typically described as a person’s breadth and depth of acquired knowledge of the language, information and concepts of a specific culture, and the application of this knowledge. Gc is primarily a store of verbal or language-based (‘knowing what’) and procedural (‘knowing how’) knowledge acquired…during formal and informal educational and general life experiences. Dr. Kevin S. McGrew (Reference)
Tests of Crystallized Intelligence
Language development, Lexical knowledge, Listening ability, General (verbal) information, Information about culture, Communication ability, Oral production and fluency, Grammatical sensitivity.
Fluid intelligence (Gf)
Our fluid intelligence (Gf) is our reasoning, problem solving and learning ability in new situations.
Definition of Fluid Intelligence (Gf)
Fluid intelligence (Gf) refers to the ability to reason and to solve new problems independently of previously acquired knowledge. …it allows us to adapt our thinking to a new cognitive problem or situation. Gf is critical for a wide variety of cognitive tasks, and it is considered one of the most important factors in learning. Susanne Jaeggi
Fluid intelligence is used for:
- problem solving
- making inferences
- deductive and inductive reasoning
- concept formation and classification
- generating and testing hypotheses
- seeing relations and patterns
Tests of Fluid Intelligence
Deductive reasoning, inductive reasoning (Matrices tests, such as Ravens Advance Progressive Matrices), quantitative reasoning, and speed of reasoning.
Visual spatial intelligence (Gv)
Our visual spatial intelligence (Gv) is our the ability to manipulate mental visual images to solve problems.
Definition of Visual Spatial Intelligence (Gv)
The ability to generate, store, retrieve and transform visual images and sensations. Gv abilities are typically measured by tasks (figural or geometric) that require the perception and transformation of visual shapes, forms or images and/or tasks that require maintaining spatial orientation with regard to objects that may change or move through space. Dr. Kevin S. McGrew
Tests of Visual Spatial Intelligence
Visualization. Spatial relations. Visual memory. Spatial scanning. Serial perceptual integration. Length estimation. Visual illusions. Imagery.
Processing speed (Gs)
Processing Speed is the speed at which basic cognitive processes are executed.
Definition of Processing Speed (Gs)
Processing speed, a mental efficiency factor, determines the speed of scanning, reading, writing and reasoning. It is defined as:
The ability to automatically and fluently perform relatively easy or over-learned elementary cognitive tasks, especially when high mental efficiency (attention and focused concentration) is required. Dr. Kevin S. McGrew
Tests of Processing Speed
Perceptual speed. Rate of test taking. Speed of reasoning. Reading speed. Writing speed.
Short Term Memory / Working Memory (Gsm)
Short term memory and working memory are both aspects of a short term information storage systems for integrating and processing the information that is attended to while thinking, comprehending and decision-making.
Definition of Processing Speed (Gs)
A definition of short-term memory (Gsm) is:
The ability to apprehend and maintain awareness of a limited number of elements of information in the immediate situation (events that occurred in the last minute or so). A limited-capacity system that loses information quickly through the decay of memory traces, unless an individual activates other cognitive resources to maintain the information in immediate awareness. Dr. Kevin S. McGrew (reference)
The ability to manipulate information while screening out distracting information is a type of short-term memory called working memory. With working memory you think with and comprehend information, as well as briefly storing it.
Tests of Short Term Memory / Working Memory
Memory span. Working memory capacity. The n-back is a direct test of working memory capacity.
Quantitative intelligence (Gq)
Quantitative intelligence is our store mathematical knowledge and quantitative reasoning ability.
Definition of quantitative intelligence (Gq)
Quantitative intelligence is made up of other factors – particularly crystallized intelligence (Gc), fluid intelligence (Gf ) and short-term/working memory (Gsm) as described above. It is not understood as an independent factor of general intelligence in itself. It has been defined as follows:
The breadth and depth of a person’s quantitative or numerical knowledge. Gq is largely acquired through the investment of other abilities primarily during formal educational experiences. Gq represents an individual’s store of acquired mathematical knowledge. Dr. Kevin S. McGrew (reference)
Tests of Quantitative Intelligence
Mathematical knowledge. Mathematical achievement.