Final answer:
The idea that higher scores on a repeated intelligence test are due to the Barnum effect is false. Such gains are more likely due to the practice effect or the Flynn effect, which is about population-wide IQ increases over generations, not individual test-retest improvements.
Step-by-step explanation:
The statement that instances where individuals take the same intelligence test twice and receive a higher score the second time can be explained by the Barnum effect is false. The Barnum effect refers to the phenomenon where people find vague, general statements about personality as highly accurate for themselves, not an improvement in test scores due to repeated testing. When a person takes an intelligence test a second time, any improvement or higher score is more likely due to factors such as familiarity with the test format, reduced test anxiety, or a reflection of a real increase in ability due to learning and experience (practice effect). In contrast, the Flynn effect describes the phenomenon that the population's IQ scores increase over time, not on an individual's repeated test-taking occasions. Other aspects related to intelligence and intelligence testing include Terman's study on intelligence, which found subjects with high IQs to be well-adjusted and dispelled the notion of high intelligence correlating with physical weakness, and controversies such as those sparked by Arthur Jensen's research on intelligence differences among ethnic groups.