Sex Differences in IQ

In this video I consider sex differences in IQ scores. While average male and female IQ scores are comparable, there are differences in performance on certain types of tasks including verbal fluency, spatial ability, math problem-solving, use of complex prose, … Read More

What Causes IQ Differences?

In this video I address the question of what causes IQ differences between people. This relates to the nature/nurture debate in considering the strength of genes and environment and these interact to shape intelligence. Twin and adoption studies allow us … Read More

IQ Variation & Distribution

In this video I describe variation in IQ scores and the distribution of IQ scores in the general population. IQ scores follow a normal distribution with a mean of 100 and a standard deviation of about 15 points. Knowing IQ … Read More

Reliability of Assessments

In this video I explain the difference between validity and reliability and then describe several ways of assessing reliability including split-half reliability, test-retest reliability, equivalent-form reliability, and the related concept of standardization. Don’t forget to subscribe to the channel to … Read More

Assessing Assessments – Types of Validity

In this video I explain how we assess the validity of assessments that have been created for a particular property (such as intelligence). There are several types of validity that can be assessed including construct validity, face validity, content validity, … Read More

Assessing Intelligence

In this video I introduce psychometrics, the study and design of testing for traits and abilities. I describe the difference between power tests and speed tests for assessing intelligence and the importance of differentiating people in order to have a … Read More

How Should We Define Intelligence?

In this video I discuss a number of ways of thinking about intelligence and determining which skills should be considered part of intelligence. I briefly describe Louis Leon Thurstone’s primary mental abilities, Howard Gardner’s multiple intelligence theory, Robert Sternberg’s Triarchic … Read More

What is Intelligence?

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 … Read More

What is Heritability?

In this video I provide a basic introduction to twin studies and heritability scores. I explain how a heritability score tells us about the role of genes in explaining variance in a trait. I also discuss some common errors and … Read More

Types of Test Designs

In designing an intelligence assessment, I may want to know the level of difficulty that someone is capable of solving. In this case, I would probably look at whether a person is able to solve a particularly difficult puzzle or … Read More