Primary & Secondary Mental Abilities: Definition & Examples

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  • 0:03 Intelligence
  • 1:18 Primary Mental Abilities
  • 3:00 Secondary Mental Abilities
  • 5:25 Lesson Summary
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Lesson Transcript
Instructor: Devin Kowalczyk

Devin has taught psychology and has a master's degree in clinical forensic psychology. He is working on his PhD.

In this lesson, we will look into what primary and secondary mental abilities are, including fluid and crystallized intelligence and ways that they can be measured.


Intelligence is a surprising thing to measure, when you get into it. I remember one time I was working with a county program and I measured this guy's IQ. He seemed pretty normal and could hold up a conversation easily. But after measuring his IQ, it turned out that he was actually in a category labeled borderline, which is between very below average and just above mentally handicapped.

Intelligence is loosely defined as an innate ability to learn and retain information to deal with problems or situations. I say loosely for two reasons. The first, which is a general reason, is that it is not a physical structure or something that we can pull out of the head and measure. It is a theoretical construct, meaning we have learned about it from psychological experiments, testing and developed theories on how we process information. This means, while we are measuring it as a real thing, it isn't quite as easy as measuring the output of your spleen or the volume of your skull.

The second reason we are loosely defining intelligence is that there is a debate between primary and secondary mental abilities. Both of those are going to take a bit to explain, so let's make them their own sections.

Primary Mental Abilities

Primary mental abilities were first discussed by L.L. Thurstone in 1935 and could be described as latent core constructs that can explain nearly all cognitive differences. Thurstone was doing research at a time when intelligence tests were first coming on the scene and people were arguing between two basic camps. One camp stated that all intelligence was just a reflection of a single, general intelligence. Others believed that intelligence is multifaceted and that you can have higher and lower facets.

Thurstone administered dozens of psychological tests and found that, while he could not answer if intelligence all comes from a single source or is multifaceted, that we do show our intelligence in just a handful of ways. That's a little confusing, since I seem to be saying two opposite things. What Thurstone found was that when measuring intelligence, there are only a handful of aspects that really matter. For example, he found the following aspects:

  • Verbal comprehension
  • Spatial orientation
  • Inductive reasoning
  • Number facility
  • Word fluency
  • Associative memory
  • Perceptual speed

The thing is, these are fairly difficult to study on their own. Think about trying to study associative memory without also mixing in some language. Or, how does one use numbers without also using some language? Or, there may be other things influencing or supporting these primary mental abilities. To fully grasp all the primary abilities, we are going to need to look at secondary mental abilities.

Secondary Mental Abilities

Secondary mental abilities are organized clusters of primary mental abilities. Sorry about using 'primary mental abilities' in the definition of secondary, but it was the best way to explain it. Basically, primary mental abilities are like pieces of an erector set or Legos. On their own, they are unique and exclusive ways to measure intelligence, but you can't really do much with a single Lego or a piece of an erector set. What secondary mental abilities do is hook primary mental abilities together into something measurable and functional.

The two big pieces of secondary mental abilities are looking at whether information is new to the person or if the information is already known by the person. Fluid intelligence is a person's ability to think laterally and understand new and novel ideas. This is one type of mental ability that decreases as we age, and basically consists of most of the primary abilities dealing with taking in new information and then figuring it out.

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