Vocabulary asks the person to define a word in their own words
In the WAIS Vocabulary subtest, the person explains the meaning of a presented word aloud. They do not choose the correct answer from a set of options; they must formulate a definition of what the word means.
In the Japanese WAIS-IV, Vocabulary is a core subtest of the Verbal Comprehension Index, or VCI, alongside Similarities and Information. The person must do more than recognize that they have encountered the word. They must retrieve its meaning and express it in an explanation that another person can understand.
In the 2024 US WAIS-5, Vocabulary is a primary VCI subtest and is also used to calculate FSIQ.
The response does not need to reproduce a dictionary entry word for word. What matters is whether it captures the central meaning accurately and includes enough information to define the word. Naming a situation in which a word is used or something associated with it does not show the same depth of understanding as explaining the meaning of the word itself.
Vocabulary scores reflect breadth, depth, and the ability to explain meaning
The Vocabulary score is not determined only by how many words a person knows. Three aspects overlap in each response:
- Breadth of vocabulary — exposure to many words and knowledge of their meanings
- Depth of meaning — precise understanding of a word's scope, including how it differs from similar words
- Ability to explain — retrieving the necessary meaning and expressing it as a concise definition
A word can feel familiar even when only a situation or impression comes to mind when its meaning is requested. The open-response format makes the difference between recognizing a word and being able to define it more visible.
These are not three separate official scores. They are useful dimensions for understanding one Vocabulary score. The task strongly reflects language and meaning knowledge accumulated through reading, learning, conversation, and work rather than novel reasoning performed in the moment.
What higher and lower Vocabulary scores can show
In the Japanese WAIS-IV, a higher scaled score indicates a strength in retaining precise meanings for a broad range of words, retrieving the relevant sense when asked, and explaining it as a definition.
A lower score means that some part of retrieving a word’s meaning and turning it into an accurate definition was more demanding. The pattern of responses can make the source more specific:
- If unfamiliar words become more frequent, breadth of vocabulary may be contributing strongly to the score.
- If related situations or impressions come to mind but the central meaning remains vague, depth of meaning may be more demanding.
- If the meaning is understood but the explanation does not come together, retrieving the relevant sense or constructing the definition may be affecting performance.
The Japanese WAIS-IV scaled score compares performance with the same-age normative group. Within the person's own profile, comparing Vocabulary with Similarities and Information can help distinguish a relative strength in vocabulary knowledge from a relative strength in reasoning with acquired knowledge. How to read WAIS results explains how to combine these two comparisons.
How Vocabulary differs from Similarities and Information
Vocabulary, Similarities, and Information all draw on acquired language and semantic knowledge. They differ in the final response required.
| Subtest | Direct task | Main processing involved |
|---|---|---|
| Vocabulary | Explain the meaning of one word | Retrieving vocabulary, distinguishing precise meanings, and expressing a definition |
| Similarities | Explain what two words have in common | Comparing concepts, generating a shared relationship, and verbal abstract reasoning |
| Information | Answer a question about a general fact | Retrieving acquired general knowledge |
If Vocabulary is lower than Similarities, defining one word precisely was more demanding than reasoning toward a concept shared by two words. If Similarities is lower than Vocabulary, comparing known meanings and forming a higher-order concept was more demanding than retrieving individual definitions.
BrainTypeIQ Vocabulary (Antonyms) focuses on distinguishing word meanings
BrainTypeIQ Vocabulary (Antonyms) presents a word and asks the person to choose its most appropriate antonym from several options.
WAIS Vocabulary requires a free-response spoken definition. BrainTypeIQ reduces the demand involved in composing a definition and focuses on distinguishing the precise meaning relationship without being drawn toward a synonym or a merely related word. Its items, administration, scoring, and comparison norms are separate from WAIS. The selection format gives BrainTypeIQ a focused way to examine word knowledge within its verbal-comprehension domain.