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Book Review: Jensen, A. R. (2006). Clocking the mind: Mental chronometry and individual differences. Amsterdam: Elsevier. (ISBN 978-0-08-044939-5)

The title of Jensen’s new work, Clocking the Mind: Mental Chronometry and Individual Differences, conjures up the image of a runner, mentally itching to be released at the starting gates. It is quite fitting in the sense that the purpose of using elementary cognitive tasks (ECTs), the building blocks of chronometric research, is to capture snapshots of the mind in its purest short sprints in an attempt to better understand not only its systematic inner workings but also the implications for the same mind when running a marathon as the incremental aggregation of the brain sprinting smaller distances that add up over time to create an individual’s intellectual life. Opening with an historical account of the origins of reaction time (RT) research in both psychology and astronomy, Jensen demonstrates how individual differences made a difference in the recording of “the time that a given star crossed the hairline in a telescope” (p. 2), sparking the correction of visual recordings of time for individual differences in measurement error. Jensen opens with this simple, relevant story and then pushes forward with another example: how Sir Francis Galton’s attempts at measuring RT and correlating it with other variables (e.g., intelligence) failed partly because of the imperfections in the instrumentation and partially because of other factors. Jensen writes,