Working memory

Why it matters for IQ scores

Many reasoning items are hard not because any one rule is obscure but because several rules must be held at once. A matrix with one rule is easy to keep in mind. A matrix with three rules, running across rows and down columns, asks you to track all three while you scan eight options. That load is where working memory shows up in an IQ test.

An example

In a hard matrix you might find that the shape cycles across each row, the fill cycles down each column, and the count goes up by one. You can write these down, but on a timed test most people hold them in mind. If one rule slips while you check the options, a near-miss distractor that breaks only that rule looks correct. Try the difference between easy and hard matrix puzzles.

Practical tips

• Name each rule in a few words as you find it.
• Describe the missing tile fully before you look at the options.
• Check options one rule at a time, crossing out any that fail.

Common confusions

Working memory is not the same as long-term memory or knowledge, and it is not the same as processing speed, though tasks often draw on both. See also fluid intelligence, mental rotation and matrix reasoning, explained.

How much it holds, and how it relates to IQ

Nelson Cowan's review put the central capacity limit at about four chunks on average (Cowan, 2001). A reanalysis of 14 data sets found a median correlation of .72 between working memory capacity and fluid reasoning (Kane et al., 2005). The full explanation: what working memory is.