FSIQ is the WAIS overall IQ score
FSIQ stands for Full Scale IQ. It combines performance across several cognitive domains to represent the broad level of general intellectual ability.
IQ is a general term for intelligence-test scores. FSIQ is the name of the overall IQ produced by the designated WAIS subtests. When someone refers to “my WAIS IQ,” they usually mean FSIQ; IQ and FSIQ are not two separate overall scores.
FSIQ uses a scale with a mean of 100 and a standard deviation of 15. IQ score bands and percentiles explains what different levels on that scale mean.
FSIQ is closely related to general intelligence
Verbal reasoning, visual analysis, working memory, and processing speed involve different tasks, yet performance across cognitive tasks tends to be positively related. The ability common across many tasks is described as general intelligence, or the g factor.
FSIQ is the WAIS composite that represents this broad general level most fully, using performance across several domains. The g factor explains the theoretical concept behind the shared variation across tasks.
The same FSIQ can come from different index profiles
Two people can have the same FSIQ even if one has similar scores across all indexes and the other has high verbal comprehension with lower processing speed. Their overall level may be similar, but the tasks in which they can express that ability most easily can differ.
FSIQ represents the overall level; index scores show how that level was produced. Both are needed to understand the result.
How to read WAIS results connects both parts of the result.
WAIS-IV uses 10 subtests and WAIS-5 uses 7 for FSIQ
| WAIS-IV FSIQ | WAIS-5 FSIQ |
|---|---|
| Similarities | Similarities |
| Vocabulary | Vocabulary |
| Information | — |
| Block Design | Block Design |
| Matrix Reasoning | Matrix Reasoning |
| Visual Puzzles | — |
| Digit Span | Digit Sequencing |
| Arithmetic | — |
| Symbol Search | — |
| Coding | Coding |
| — | Figure Weights |
In WAIS-IV, the 10 core subtest scaled scores are combined and converted to FSIQ. In WAIS-5, seven designated subtests are combined instead. In both editions, FSIQ is not a simple average of the index scores.
Information, Visual Puzzles, Arithmetic, and Symbol Search remain part of WAIS-5 and contribute elsewhere within its index structure. WAIS-IV and WAIS-5 compared explains the reorganisation.
FSIQ and the profile work together
FSIQ answers how the person performed across the assessment as a whole. Index and subtest scores explain which cognitive demands raised or lowered that overall performance. Using both gives a more useful account than discarding either one.
WAIS index scores explains the component domains. If the report includes General Ability and Cognitive Proficiency composites, GAI and CPI show how they divide the profile in another way.