Duke TIP

Nonverbal Intelligence Tests

DGL: IQ tests measure a wide range of cognitive abilities. Do nonverbal tests measure as wide a range of skills?

Donna Ford: Traditional intelligence tests have different scales and measure different cognitive abilities or skills. However, nonverbal tests have fewer scales and therefore do not measure as wide a range of skills.

Linda Kreger Silverman: Nonverbal tests have been considered pure measures of general intelligence and are excellent indicators of abstract reasoning, particularly in the visual-spatial domain. These instruments have negligible ethnic biases, and I support their use in identifying gifted children from culturally diverse groups.

However, they do not measure as wide a range of abilities as IQ tests and would not be as predictive of success in a gifted program.

DGL: How would you reconcile poor results on a nonverbal test with a high score on a traditional IQ test?

Ford: The correlation between any two tests is imperfect. So it is possible for a child to have a high score on a traditional IQ test and a low nonverbal test score, and vice versa. Students who have limited proficiency in English, are underachievers, and are culturally diverse are most likely to score high on nonverbal tests.

Silverman: Some children obtain inconsistent test scores because of the test format itself. A child’s performance on one test will never perfectly predict his or her performance on another test.

DGL: Is there evidence that a student who does well on a nonverbal test but not on an IQ test will demonstrate high academic performance?

Ford: It is possible for a student to have a high nonverbal score and high academic achievement, depending on how achievement is measured. Is it measured by an achievement test? By grades? By an end-of-term project? Tests that measure intelligence nonverbally are likely to capture the strengths of, and not to penalize as low achievers, students who cannot read, who have poor language skills, who are bilingual, and so on.

Silverman: I am unaware of such evidence. Many school districts complain that children who do well on the Raven’s Standard Progressive Matrices but do poorly on more verbally loaded intelligence tests also do poorly in their gifted programs. This is because most gifted programs are highly verbal. It would be interesting to design a program more suited to children who perform well on nonverbal measures.

It is advisable to administer a vocabulary test along with the Raven’s to gain a fuller picture of a child’s abilities.

DGL: Do you recommend eliminating IQ tests and using only nonverbal intelligence tests? Why or why not?

Ford: I do not recommend eliminating IQ tests, but I do recommend decreasing considerably the privilege and power that we grant them. Tests should be used to inform educators about the needs and strengths of students. Too often they are used to sort and place. Traditional and nonverbal tests should be used along with grades, projects, and teacher and family information to make informed, responsible decisions about all students, not just culturally diverse ones. Nonverbal test scores provide useful information.

Silverman: We need both. Eliminating verbal tests would prevent us from discovering children with high verbal abilities, such as those in studies of African American children who show extremely high performance on verbal tasks. Nonverbal tests are often unprotected, meaning that anyone can administer them without the rigorous training that makes proper interpretation of the results possible. Nonverbal tests are often administered to groups, but individualized IQ tests are essential to discovering learning disabilities. Nonverbal tests have low ceilings. So it would be impossible to discover profoundly gifted children solely through nonverbal tests. Lastly, gifted girls tend to be highly verbal, and they should not be sacrificed in the attempt to make tests responsive to ethnicity. Gender is important, too.

- Donna Ford, PhD, is professor of gifted education at Ohio State University.

Linda Kreger Silverman, PhD, is director of the Institute for the Study of Advanced Development and of the Gifted Development Center in Denver, Colorado. Her newest book, Upside-Down Brilliance: The Visual-Spatial Learner, discusses right hemispheric gifts

Nonverbal Intelligence Tests

  • Naglieri Nonverbal Abilities Test
  • Raven's Standard Progressive Matrices
  • Universal Nonverbal Intelligence Test