Coding asks the person to write the symbol paired with each number
In the WAIS Coding subtest, the person uses a key that pairs numbers with symbols and writes the corresponding symbol beneath each number in a sequence. The same process is repeated for two minutes to measure speed and accuracy.
In the Japanese WAIS-IV, Coding is a core subtest of the Processing Speed Index, or PSI, together with Symbol Search. The defining feature is the continuous cycle of looking between the work area and the key, matching a number with a symbol, and reproducing the symbol by hand.
In the 2024 US WAIS-5, Coding remains a primary PSI subtest and is also used to calculate FSIQ.
The number of correct symbols written in two minutes is converted using age-based norms
In the Japanese WAIS-IV, the raw score is based on the number of symbols written correctly within two minutes. Incorrectly copied symbols are not counted as correct, so the person must continue writing while checking each number-symbol match accurately.
The raw score is converted to a scaled score using the Japanese edition's age-based norms. A higher or lower score therefore describes how quickly and accurately the person completed the sequence from checking the key to writing the symbol compared with people of the same age.
Visual search, matching, and handwriting are central, with associative learning also involved
Coding repeats several processes at short intervals:
- identify the next number in the work area;
- find the same number in the key;
- distinguish the symbol paired with that number;
- retain the symbol's form long enough to write it accurately; and
- move to the next number after finishing the response.
The score strongly reflects visual search between the key and work area, number-symbol matching, and the speed of fine written output. Repetition can also produce some associative learning as the pairings become more familiar, but the central demand remains cycling quickly through finding, matching, and writing.
What higher and lower Coding scores can show
A higher Japanese WAIS-IV Coding score indicates strength in finding the necessary symbol in the key, reproducing it accurately, and moving smoothly to the next item at an efficient pace.
A lower score means that more time was spent searching the key, matching the number and symbol, reproducing the fine visual form, checking an entry, or correcting a written response. Slower handwriting or difficulty with fine motor movement can affect Coding more strongly than Symbol Search because Coding requires the symbol itself to be drawn. Characteristics of lower processing speed explains how related demands can appear in work and learning.
If Coding is clearly lower than Symbol Search, reproducing symbols or learning the number-symbol associations may have created more demand than visual search alone. If Symbol Search is lower, scanning several symbols and making a present-or-absent decision may have been more demanding than writing from a key. How to read WAIS results explains how to interpret the difference within the full profile.
How Coding differs from Symbol Search and Cancellation
| Subtest | Direct task | Processing emphasized |
|---|---|---|
| Coding | Write the symbol paired with each number | Searching and matching a key, written symbol production, and associative learning |
| Symbol Search | Decide whether either target appears in a small set of symbols | Focused visual search, shape matching, and present-or-absent decisions |
| Cancellation | Find and mark targets in a broad array of figures | Wider visual scanning, selective attention, and avoiding responses to distractors |
Symbol Search requires a simple marked response rather than drawing the symbols. Cancellation repeatedly searches a broad array for figures that meet the same target rule without returning to a number-symbol key.
BrainTypeIQ Symbol Search removes the handwriting demand of Coding
BrainTypeIQ Symbol Search compares two targets with five search symbols and records a present-or-absent decision through on-screen buttons. It does not use a number-symbol key or require the person to draw symbols.
BrainTypeIQ therefore focuses on visual search, matching, and decision speed rather than the fine motor and associative-learning demands of Coding. Its items, online administration, timing, scoring, and comparison norms are separate from WAIS. This lets BrainTypeIQ measure rapid visual search and matching within its five-domain cognitive profile without adding Coding's handwriting demand.