The Relational Abilities Index+: Initial Validation of a Functionally Understood Proxy Measure for Intelligence

Colbert et al. (2020) built a 15-minute test called the RAI+. It measures how people solve new problems without words. The team gave the RAI+ to the adults along with full IQ tests and math quizzes.

They wanted to see if the short test could stand in for the long ones. They also checked if scores matched years of school finished.

RAI+ scores tracked closely with IQ scores (r = .79) and math scores (r = .75). A strong score on the 15-minute test almost always meant a strong score on the 90-minute IQ battery.

School years, however, did not line up. Some adults with high RAI+ scores had only finished grade 10. Others with low scores held college degrees.

Christensen et al. (2024) showed the K-BIT, another brief IQ tool, slightly underestimates adult scores in Prader-Willi syndrome. RAI+ avoids this problem by using learning tasks instead of vocabulary.

Knapczyk (1989) built a three-test battery to separate mental retardation from psychosis when IQ alone failed. RAI+ updates the same speed-versus-accuracy idea for today’s clients.

Ohan et al. (2015) tracked non-verbal IQ in autism from . A quick tool like RAI+ could make that long watch easier without repeated long tests.

You can swap the 15-minute RAI+ for a full IQ test when you need a fast estimate of reasoning. Use it at intake, reassessment, or when clients fatigue easily. Just remember: it tells you how well they think, not how far they went in school.