Working-memory span
Also known as: Memory span
How much information you can actively hold and juggle at one time.
What it means
Working-memory span is the measured capacity of the system that simultaneously stores and manipulates information in the service of ongoing cognition. Simple spans (like digit span) index storage alone, whereas complex spans (such as reading or operation span) interleave storage with processing and predict higher-order abilities far better. Individual differences in complex span correlate substantially with reading comprehension, reasoning, and fluid intelligence, making it one of cognition's most consequential capacity measures. Debate continues over whether the limit reflects a fixed number of slots, a shared resource, or the dynamics of attention and interference. The construct anchors theories of how a sharply bounded mental workspace constrains thought.
Examples
Solving a multi-step arithmetic problem in your head while remembering the intermediate totals taxes working-memory span.
Reading a long sentence with a clause buried in the middle: by the time the verb arrives, some readers have lost the subject — which is why complex span predicts comprehension.
A simultaneous interpreter holds the tail of one sentence while speaking the start of it aloud — storing and processing at once, exactly what complex span tasks measure.
First described in Complex span: Daneman & Carpenter (1980).