Judging membership in a memory set takes longer linearly as the set grows

What it is

In Sternberg memory scanning, people memorise a small set, then judge whether a probe belongs to it. Reaction time rises approximately linearly with memory-set size. This describes short-term memory membership judgments, not a claim that every task becomes linearly slower with more visible items.

Why it happens

Each additional remembered item contributes evidence that must be processed; under standard conditions this average increment is stable, producing a line. The intercept also contains encoding and response stages that do not vary with set size.

Studying it

Randomise set size and probe, fit reaction-time–set-size functions separately for positive and negative responses, and record accuracy. Control item identity, practice, and response mapping. Segment memory presentation, probe judgment, and key movement before interpreting a slope as scanning cost.

Where it stops holding

The relation rests on small sets, discrete items, and brief retention. Semantic materials, visual search, long-term retrieval, or concurrent maintenance introduce other processes. A slope is a conditional group average, not a prediction of one judgment.

Related

• Same group: B1.06.2 Scanning is exhaustive rather than self-terminating · B1.06.3 The finding concerns memory judgment, not visual search · B1.06.4 Reaction time rises by tens of milliseconds per remembered item · B1.06.5 Similar slopes for yes and no responses indicate exhaustive scanning · B1.06.6 The result concerns small short-term sets, not long-term retrieval · B1.06.7 Using the law to set an interface-option limit is a cross-paradigm error
• Nearby: B1.04 Hick-Hyman law · B1.07 Power law of practice
• Search terms: Sternberg memory scanning · memory set · reaction time