Far from being an indefinable concept, a single measure of intelligence underpins our problem-solving, musicality and even creativity and emotional skills

When researchers talk about intelligence, they are referring to a specific set of skills that includes the abilities to reason, learn, plan and solve problems. The interesting thing is that people who are good at one of them tend to be good at all of them. These skills seem to reflect a broad mental capability, which has been dubbed general intelligence or g.

That’s not to say people don’t specialise in different areas. Some will be particularly good at solving mathematical problems, others will have particularly strong verbal or spatial abilities, and so on. When it comes to intelligence tests, although these specific skills account for about half of the variation between people’s performance, the other half is down to g. “If you took a sample of 1000 people and gave them all IQ tests, the people who do better on the vocabulary test will also do better, on average, on the reaction speed test, and so on,” says Stuart Ritchie, an intelligence researcher at the University of Edinburgh, UK.

Our thinking on human intellect is clouded with misinformation. But the latest science of intelligence is surprisingly enlightening.  This seems to fly in the face of old ideas. In the early 1980s, Harvard psychologist Howard Gardner argued for the existence of multiple intelligences, including “bodily-kinaesthetic”, “logical-mathematical” and “musical”. However, most researchers now believe these categories reflect different blends of abilities, skills and personality traits, not all of which are related to cognitive ability. Likewise, recent research indicates that so-called emotional intelligence – the ability to regulate one’s emotions and relate to other people – is simply a mixture of general intelligence and personality.

Even creativity is related to g. There is a linear correlation up to an IQ of about 120 – classified as above average intelligence – although the link breaks down after that. “The idea that you can be creative without being intelligent is a myth: it takes a certain level of intelligence to acquire raw data to be creative with,” says neuropsychologist Rex Jung at the University of New Mexico.

So, what is the biological basis of g? One suggestion is that it reflects “mental energy”: the brains of people with high IQs seem to use less energy when performing mental tasks, and their neurons conduct signals faster. Possibly then, clever brains are more efficient. Another idea is that smart people have greater working memories, so can hold onto and process more information at any given moment. For now, the g-factor has a lot in common with the X factor: we don’t know precisely why it makes someone stand out, just that it does.
(Linda Geddes, New Scientist 22 July 2018)

An Epicurean enjoys the company and friendship of intelligent people, but also respects the conversation and views of those who haven’t been so amply blessed.  Some call it “being a lady or a gentleman”.