Day 45 of 150 Speed Difficulty 5/10
Inspection time correlates with IQ at roughly r = −0.4
Quick answer
Inspection time correlates with IQ at roughly r = −0.4. Today's question (Inspection time) asks about a finding from Vickers, D., Nettelbeck, T., & Willson, R. J. in 1972. The correct option is r = -0.3 to -0.5 (faster IT, higher IQ) — full explanation, primary source, and glossary cross-links below.
Today's question
"Inspection time" — the briefest stimulus duration that allows reliable perceptual discrimination — correlates with general intelligence at roughly:
Reveal the answer and explanation
Correct: B — r = -0.3 to -0.5 (faster IT, higher IQ)
Vickers, Nettelbeck & Willson (1972) introduced the inspection-time paradigm: present a brief stimulus, mask it, and find the duration at which the observer can reliably discriminate (e.g., which of two lines is longer). Across decades of replications, faster inspection times correlate with higher IQ at roughly r = -0.3 to -0.5 — substantial for a perceptual measure that does not require speeded responses or strategy. The result is a major piece of evidence that elementary processing speed contributes to general cognitive ability.
About the source
Vickers, D., Nettelbeck, T., & Willson, R. J. (1972). Perceptual indices of performance: The measurement of "inspection time" and "noise" in the visual system. Perception, 1(3), 263–295.
Every Cognition Bible question cites a primary source — a paper, book chapter, or monograph that exists, that we can point to on Google Scholar, and whose finding the question accurately summarizes. No fabricated authority strings, no name-drops without paper-level grounding.
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