Similar slopes for yes and no responses indicate exhaustive scanning

What it is

In memory scanning, positive probes and negative probes have similar reaction-time slopes as set size grows. This pattern is central evidence for exhaustive scanning: on average, finding a match does not terminate the comparison early.

Why it happens

With self-termination, positive probes would finish around the middle of a scan whereas negatives would cover the full set, so the positive slope should be about half the negative slope. Similar slopes indicate comparable set-size-related processing. Intercepts can still differ because affirmative and negative decision stages need not be identical.

Studying it

Balance positive and negative trials, randomise the probe's serial position in the presented set, and regress the two response types separately. Compare confidence intervals or a slope interaction rather than judging whether two plotted lines look parallel. Inspect accuracy and response bias to avoid a speed–accuracy artefact.

Where it stops holding

Similar slopes support a model in this paradigm; they do not alone prove a conscious or neural item-by-item sequence. Familiarity, chunking, cues, and unequal probability can change the result. Different response mappings can also mix motor differences into slope and intercept.

Related

• Same group: B1.06.1 Judging membership in a memory set takes longer linearly as the set grows · 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 · B1.06.6 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: exhaustive memory scanning · positive negative slope · Sternberg paradigm