How WAIS-IV and WAIS-5 indexes map to CHC abilities
Using five broad abilities from CHC theory, the main difference between the four WAIS-IV indexes and the five WAIS-5 indexes can be summarized as follows.
| CHC ability | WAIS-IV | WAIS-5 |
|---|---|---|
| Gc: crystallized intelligence | Verbal Comprehension Index (VCI) | Verbal Comprehension Index (VCI) |
| Gv: visuospatial processing | Perceptual Reasoning Index (PRI) | Visual Spatial Index (VSI) |
| Gf: fluid reasoning | Perceptual Reasoning Index (PRI) | Fluid Reasoning Index (FRI) |
| Gwm: working memory | Working Memory Index (WMI) | Working Memory Index (WMI) |
| Gs: processing speed | Processing Speed Index (PSI) | Processing Speed Index (PSI) |
WAIS-5 allows the Gv- and Gf-heavy tasks formerly combined in PRI to be read as separate VSI and FRI scores. The added index makes the structure of visuospatial processing and fluid reasoning clearer.
WAIS-IV PRI already contained both Gv and Gf tasks
The distinction existed at the subtest level in WAIS-IV even though both abilities contributed to PRI.
| CHC ability | WAIS-IV subtests | Central process |
|---|---|---|
| Gv: visuospatial processing | Block Design, Visual Puzzles, Picture Completion | Decompose and construct shapes; handle orientation and spatial relationships |
| Gf: fluid reasoning | Matrix Reasoning, Figure Weights | Derive rules from visual or quantitative relationships |
WAIS-5 did not create a new ability. It made a distinction already present among WAIS-IV subtests visible at the primary-index level.
A 2026 analysis of the 1,120-person Japanese WAIS-IV standardization sample supports this interpretation. In Bayesian model comparisons, a CHC-based five-factor model with higher-order g fit better than the conventional four-factor model.
Visual working memory and expanded WAIS-5 indexes
Beyond its primary Working Memory Index, WAIS-5 reports a Visual Working Memory Index (VWMI) from Symbol Span and Spatial Addition. Other expanded and ancillary indexes combine additional subtests to give a wider view of particular abilities.
| Index | Subtests and profile focus |
|---|---|
| Verbal (Expanded Crystallized) Index (VECI) | Similarities, Vocabulary, Information, and Comprehension for a broader view of crystallized knowledge |
| Expanded Fluid Index (EFI) | Matrix Reasoning, Figure Weights, Arithmetic, and Set Relations for a broader view of fluid reasoning |
| Quantitative Reasoning Index (QRI) | Figure Weights and Arithmetic for quantitative reasoning |
| Expanded Working Memory Index (EWMI) | Auditory and visual working-memory tasks for a broader view of working memory |
WAIS-5 has a more CHC-aligned index structure
Separating Gv from Gf and adding working-memory indexes makes WAIS-5 easier to relate to the broad-ability distinctions in CHC theory than WAIS-IV. The mapping is useful, but it is not one-to-one: every subtest draws on several processes, and an independent 2026 analysis of the 2,020-person US WAIS-5 standardization sample favored a four-group-factor model that combined Gv and Gf. VSI and FRI remain useful profile scores; their labels do not make the underlying abilities perfectly separate.
WAIS-IV and WAIS-5 compared explains the changes to subtests and FSIQ.
BrainTypeIQ calculates Gc, Gf, Gv, Gwm, and Gs separately, so you can see the five-domain cognitive profile alongside overall IQ.