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The Twenty-item prosopagnosia index 

The Twenty-item prosopagnosia index (PI20) assesses the presence and severity of prosopagnosic traits. You can complete the PI20 below. Where individuals score 65 or more, there is a good chance that they have developmental prosopagnosia. ​

Researchers may freely use the PI20 for academic purposes. Please cite the measure as follows:  

Shah, P., Gaule, A., Sowden, S., Bird, G., & Cook, R. (2015). The 20-item prosopagnosia index (PI20): A self-report instrument for identifying developmental prosopagnosia. Royal Society Open Science, 6: 140343.


Please contact the lead author ( before using the PI20 for non-research applications (e.g. on media websites, in healthcare or clinical settings).   

A printable version of the PI20 is also available for free download with guidance on scoring and interpretation. pdf

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