What GAI and CPI mean
GAI and CPI regroup WAIS subtests into two broad aspects of cognitive performance.
| Composite | Full name | What it summarizes |
|---|---|---|
| GAI | General Ability Index | Applying acquired knowledge and concepts, visual-spatial analysis, and reasoning to derive an answer |
| CPI | Cognitive Proficiency Index | Holding and manipulating information while processing simple information quickly and accurately |
Both use a scale with a mean of 100 and a standard deviation of 15. FSIQ brings a wider set of tasks together into one overall level; GAI and CPI make the contrast between knowledge and reasoning on one side and working-memory and processing demands on the other more visible.
A GAI–CPI difference shows where performance changes
When GAI is higher than CPI, understanding complex material and finding relationships or rules may be easier than retaining several pieces of information while working or producing answers under time limits. The person may understand difficult ideas well but experience more demand when they must hold information and finish within a fixed time.
When CPI is higher than GAI, retaining information and carrying out a defined process may be easier than explaining concepts verbally or finding unfamiliar relationships and rules.
The difference is most useful as a description of the task conditions in which a person can express their ability more or less easily.
The score levels matter as much as the size of the gap
The same 15-point difference can describe very different profiles. A GAI of 130 and a CPI of 115 are both above the population mean. A GAI of 100 and a CPI of 85 show the same gap, but CPI is below the same-age average.
The direction of the difference therefore does not tell the whole story. Read both score levels and the indexes and subtests that produced them.
If CPI is lower, WMI helps show whether holding and manipulating information is the main demand, while PSI shows whether rapid visual search, matching, or output contributes more. If GAI is lower, the verbal, visual-spatial, and fluid-reasoning components show where the difference arises.
How to read WAIS results places this comparison within the full profile, and WAIS index scores explains each domain.
WAIS-IV and WAIS-5 use different subtests
| Composite | WAIS-IV | WAIS-5 |
|---|---|---|
| GAI | Similarities, Vocabulary, Information, Block Design, Matrix Reasoning, Visual Puzzles | Similarities, Vocabulary, Block Design, Matrix Reasoning, Figure Weights |
| CPI | Digit Span, Arithmetic, Symbol Search, Coding | Digit Sequencing, Running Digits, Coding, Symbol Search |
GAI and CPI exist in both editions, but the component tasks are not identical. WAIS-5 also reorganizes FSIQ, the primary indexes, and the wider ancillary-index structure, so the WAIS-IV scoring structure should not be applied to a WAIS-5 report. WAIS-IV and WAIS-5 compared explains the full change.
GAI and CPI in BrainTypeIQ
BrainTypeIQ uses its own five domains and nine online tasks to show the same practical contrast between general ability and cognitive-processing demands. Its GAI is based on Gc, Gf, and Gv, while its CPI is based on Gwm and Gs. These are BrainTypeIQ scores, not interchangeable with WAIS composites.
After completing all nine tasks, the overall IQ and brain type are free. The detailed report includes the five domain scores, nine task scores, GAI, and CPI, making it possible to trace the gap back to the abilities and tasks that produced it.