- 68% of people scored between +1 and -1 standard deviation, scoring between 84 and 116 IQ points.
- 95% of people scored between +2 and -2 standard deviations, scoring between 68 and 132 IQ points.
- 5% of people scored between +3 and -3 standard deviations, scoring < 68 and > 132 IQ points.
- Most of the items rely on verbal comprehension (e.g., understanding the spoken word; Colman 1990).
- The WISC-R measures knowledge and memory rather than pure thinking abilities (e.g., problem solving and logic; Colman, 1990).
- The Flynn Effect (1994) observes that average scores on intelligence testing has grown by 15-25 points over the last generation. Flynn argues then that intelligence cannot have increased over that period, and therefore the tools used to measure intelligence over the past 20 years have been statistically flawed and are not in fact measuring the intelligence it has claimed (Note: The WISC-IV released in 2003/4 was adjusted in order to address the Flynn Effect).
- The WISC-R does not go far enough to measure what intelligence means for people of different ages (Siegler & Richards, 1982).
- The WISC-R is culturally biased; it represents learning through formal education that only Western children have access to, therefore it may not accurately measure intelligence as it is understood by children without formal education, such as in Senegal (Van de Vijver & Leung, 1997).
If you want to learn more about intelligence across cultures (and race and gender) I highly recommend the following The Psychologist article.