In this video I introduce the concept of intelligence and the difficulties of defining and measuring intelligence. I mention the tendency toward reification when thinking about IQ scores and the importance of remembering that intelligence is a hypothetical construct, not a directly observable object. I also introduce one of the first intelligence researchers, Charles Spearman, who used factor analysis to propose a definition of general intelligence as a single factor (called g-factor) which influenced multiple cognitive abilities.
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Video Transcript
Hi, I’m Michael Corayer and this is Psych Exam Review. In this video we’re going to start a unit on intelligence and testing. This means we’re going to start with a question, what is intelligence? Now you probably have a common sense understanding of intelligence and you can use this term freely and people will know what you mean when you say someone is highly intelligent but if we’re going to study this scientifically we need to have a more precise definition. So what exactly are we talking about when we talk about intelligence? Do we mean just that someone’s able to get good grades in school or do we mean that they’re able to successfully complete a complicated task? Do we mean they always know the right answer? Or maybe we mean they get to the answer faster than everyone else. Now if we’re going to study intelligence, we need to have a precise definition and we’ll see that researchers will disagree on exactly what that definition should be.
Now once we have a definition of intelligence, then we can think about attempting to measure intelligence. So hopefully we can create some sort of tests or tools that allow us to assess a person’s intelligence and hopefully those assessments allow us to make predictions about real-life outcomes. So if I know someone’s performance on some intelligence assessment then maybe I can make predictions about their school performance or their job performance or some other aspect of their life?
Now in doing this, in talking about IQ assessments, we want to be careful to avoid a tendency towards reification. So what is reification? This refers to the tendency to treat an idea as if it were a concrete object. So we have to remember that intelligence is not a directly observable object, right? If I measure some physical object in the world and I tell you it’s 20 centimeters and, you know, you can get out your ruler and measure it as well and we can pretty easily agree on, you know, the length of this physical object.
But when it comes to intelligence this is an abstract idea. It’s a hypothetical construct. It’s not something we can directly observe. That means if I give some intelligence assessment and I tell you this person scored 100 on this assessment, well, you can ask, well, how do you define intelligence? Maybe your definition is different from mine. And then you might ask, well how exactly did you measure intelligence based on that definition? And maybe we could disagree about the best measurement for that particular definition and so both of those would influence the person’s score, right? We could have the same person, if I define intelligence one way and measure it one way, and you define intelligence slightly differently and measure it slightly differently, that same person could get very different scores, right? And that’s because this is an abstract idea, it’s not a concrete object that we’re directly observing and measuring. So we want to keep that in mind when we talk about people’s IQ score, we talk about any type of intelligence assessment, it’s going to be dependent on the definitions and the particular measurement that we’ve used for intelligence.
So with that in mind we’ll look at one of the first definitions of intelligence and this comes from a researcher named Charles Spearman. Spearman proposed that intelligence is a single underlying trait and so what I mean by that is that he thought of intelligence as a single thing that influenced a broad range of abilities. So he thought you have some level of intelligence and then that influences your performance on a number of different cognitive tasks.
And Spearman didn’t just think this up, he did this based on statistics. He used a technique called factor analysis in order to try to find whether or not there was this single underlying trait. So what is factor analysis? Well, this is a statistical technique and what it involves is measuring a whole bunch of different things and then looking for patterns in that data, looking for correlations. So let’s imagine that I think of as many different tests that I can come up with for some cognitive abilities and I give you all of these tests. I say “Ok, test A is going to be some sort of reading comprehension test and, you know, test B is a math solving, math problem-solving test, and test C is a verbal fluency test, and test D is a reaction time test. And, you know, I come up with all sorts of different tests and the idea is that if I knew your score on one test, would I be able to make predictions about your score on another test? So if I knew that you did really well on reading comprehension, you know, could I make a prediction about your math performance? Or if I knew your math performance, maybe I could make a prediction about your verbal fluency, or your reaction time, or you know any number of things.
I might wonder about all of these different relationships between all of the things that I’ve measured and I would do this for a number of different people. So I give all these people all these different tests here and what I’d hope to find is patterns that allow me to make predictions. And ideally what I would find is that there might be one thing that allows me to predict all of these scores. So I might have one thing, I’d say “Ok this thing here tells me about all of the performances on all these different skills”.
And this is what Spearman found. He found that he could find a single factor that predicted performance on lots of different skills. So he said “Ok, people who do well on A, essentially that means they’re likely to do well on B, and C, and D. People who do poorly on A also do poorly on B, and C, and D. And this indicates that there’s a single factor influencing all of them and what Spearman referred to this factor as is “g-factor“. And this stands for general intelligence.
So the idea of general intelligence is that you have some level of general intelligence and that influences your performance on a large number of different cognitive skills. Now not all researchers agree with Spearman’s definition of intelligence and we’ll get into some other proposed definitions in the next video but we’re going to continually come back to this idea of g-factor because the evidence for general intelligence is pretty strong. It does seem to be the case that you have some level of this general intelligence and it influences performance on lots of different types of tasks. Ok, I hope you found this helpful, if so, please like the video and subscribe to the channel for more. Thanks for watching!
