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Towards a best practice for measuring digit ratio in psychological research: Current methods compared and evaluated by means of radiographic hand imaging

Research project Digit ratio (DR) is considered a marker of early hormone exposure, which has permanent effects of the organisation of the developing brain. It is unique in that it is the only way to measure such exposure during a critical period (pre-natal) retrospectively (throughout the rest of life), and has as of today been applied in more than 1,400 studies.

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Project overview

Project period:

Start date: 2016-01-01

Participating departments and units at Umeå University

Department of Psychology

Research area


Project description

Digit ratio (DR) reflects the relation between the lengths of the fingers, typically the 2nd digit divided by the 4th. It is assumed to reflect hormone exposure in the womb, with implications for a range of psychological traits and behaviours. Results involving DR are sometimes inconsistent, one reason being that measurement methods vary across studies. The purpose of this project is to evaluate and compare these methods to the underlying basis of radiographic imaging of each bone in the fingers, assessing inter-method and inter-rater reliability and other differences across methods.