An analogy refers to a similarity in behaviour, function, or relationship between entities or situations that are in other respects different from each other. The prefrontal cortex is involved in analogical reasoning. Analogical reasoning uses multiple areas in the prefrontal cortex, unlike simple semantic retrieval.

Inductive reasoning or induction is the attempt to infer some new principle or proposition from observations or facts that serve as clues. It is also called hypothesis construction. It is reasoning that is founded on perceived analogies or other similarities. Inductive reasoning is prone to several biases:

1. Availability bias
   People tend to rely too strongly on information that is readily available to us and ignore information that is less available (e.g: people tend to believe that a lot of people die from shark attacks because it gets a lot of news coverage, but this is not correct).
2. Confirmation bias
   People tend to look for information that confirms the hypothesis, rather than look for information that disproves the hypothesis.
3. Predictable-world bias
   People tend to believe that there are patterns in the world that do not exist (e.g: in a game of chance people that have seen a certain card a few times tend to go for another card, even though the probability is just as high, because they feel like the first card can’t come up again).

Deductive reasoning is the attempt to derive logically the consequences that must be true if certain premises are accepted as true. There is a bias in deductive reasoning. This occurs when people tend to use their knowledge rather than formal knowledge in answering deductive reasoning questions.

Insight problems are problems that are specifically designed to be unsolvable until one looks at them in a different way. These problems are generally very difficult, because their solution depends on abandoning a well-established habit of perception or thought, referred to as a mental set, and then viewing the problem in a different way. There is a mental set known as functional fixedness, in which there is a failure to see an object as having a function other than its usual one. There is a design stance in which people assume that some tools are designed for an intended function. This leads to more user-efficiency. People solve insight problems best if they take some time off from the problem, do something else and come back to it. This is known as the incubation period.

The broaden-and-build theory states that negative emotions tend to narrow one’s focus of perception and thought. The understanding of what is expected of a participant in a test is culturally dependent. People from non-western cultures are also more likely to sort things by function instead of taxonomy. In cultures such as China and Japan, the reasoning is more holistic and less individually centred.

In the early ages of intelligence testing, the testing of intelligence was focussed on schoolwork, rather than other intelligence-related concepts, such as abstract thinking or logical reasoning. The first intelligence test commonly used in North America was the Stanford-Binet Scale. This intelligence test, tested verbal comprehension, perceptual processing, working memory and processing speed. This test gives you an IQ score as a result and the average IQ of the population is 100.

The strength of the correlation between performance on the job and IQ depends on the type of job. There is a positive correlation, but the correlation gets stronger with more demanding jobs.

The positive manifold holds that scores always correlate positively with one another if the sample Is large enough when giving different mental tests to people who are part of the same broad cultural group. General intelligence (g) is the underlying ability that contributes to a person’s performance on all mental tests. General intelligence is usually measured by getting the average of several mental tests, which is done in most IQ tests nowadays.

Cattell argued that general intelligence consists of two parts that correlate positively with each other:

1. Fluid intelligence
   This is the ability to perceive relationships among stimuli independently of all previous specific practise or instruction concerning those relationships (e.g: finishing a pattern of not previous seen symbols). Tests in this category depend on ‘raw reasoning’.
2. Crystallized intelligence
   This is the mental ability derived directly from previous experiences (e.g: a test of knowledge). Tests in this category depend on previously learned information.

There is a positive correlation between general intelligence and mental speed, the inspect time that is required to detect certain patterns. The working-memory span also positively correlates with general intelligence. People with higher general intelligence perform better on executive function tasks. It is possible that general intelligence has been selected during human evolution because it helps us deal with novel problems.

Heritability is the degree to which variation in a particular trait, within a particular population of individuals, stems from genetic differences as opposed to the environmental differences. This is often quantified by the heritability coefficient. It does not say anything about how much of any trait is due to genetic factors, only what percentage of the difference in a trait within a specific population can be attributed to inheritance. Heritability is relative, varying with the environmental conditions in which people within the population live.

Heritability=r identical twins-r nonidenticaltwins*2

When the heritability is 1.0, it means that the environment for everyone in the population is the same and the differences in the population are fully caused by differences in genes. If the heritability is 0.0, it means that the genes are exactly the same for everyone and all the differences are caused by differences in the environment.

The influences of families on intelligence exists, but this effect disappears in early adulthood because by then the individuals choose their own environment.

If there are two wheat fields, each planted from the same package of genetically diverse wheat seeds, but with different soils, then there will be big differences between the wheat fields, but the differences within a wheat field are determined by genes and not the differences between the wheat fields.

There is a difference in IQ scores in the United States between blacks and whites, because of the social designation of black and white. Besides that, there is a stereotype threat. Stereotypes of a race influence the results on an IQ test.

Involuntary or castelike minorities on average score lower on IQ scores, because they are treated differently by society, than voluntary minorities. The Flynn-effect is the effect that the average IQ rises 9 to 15 points every 30 years. This effect could occur because of the improvements in modern life. More people receive education, more people have intellectual demanding jobs and modern technology is also increasingly intellectually demanding.