Evaluating a screening questionnaire for lifelong face-recognition difficulties
Recognizing a familiar face, whether it's greeting a colleague or spotting a friend in a crowd, plays an important role in social interactions. However, for people with lifelong difficulty processing familiar faces, these effortless tasks can be quite challenging.
A recent study has evaluated the 20-item prosopagnosia index (PI20), a widely used self-report questionnaire designed to identify developmental prosopagnosia - a condition characterized by lifelong difficulties recognizing faces. The research, conducted by Associate Professor Masaki Mori and former graduate student Midori Sugiyama from Japan Advanced Institute of Science and Technology and Keio University, respectively, was published in the journal Behavior Research Methods.
Developmental prosopagnosia affects an individual's ability to recognize familiar faces, despite having normal vision and no brain injuries. Often, this condition remains undiagnosed due to the absence of accurate screening tools. The PI20 questionnaire addresses this issue by asking participants to rate their agreement with statements about everyday face-recognition experiences.
To assess the questionnaire's effectiveness, the researchers employed two complementary statistical approaches: classical test theory and item response theory. These methods analyzed how well the PI20 consistently measures what it intends to measure and evaluated how well each question distinguishes between individuals with varying levels of face-recognition difficulty.
The results, published on August 12, 2026, confirmed that the PI20 has excellent reliability and validity as a screening tool, effectively differentiating between those with and without face-recognition challenges.
The study identified that two specific questions - one regarding recognition of people with distinctive facial features and another concerning recognizing one's own face in photographs - contributed little to measuring face-recognition difficulty. These questions may not effectively capture the unique face-recognition difficulties associated with developmental prosopagnosia.
Additionally, the researchers made available one of the largest PI20 datasets and the accompanying analysis code, which could be beneficial for future studies across different languages and cultures. Overall, this study enhances the scientific foundation of the PI20 questionnaire, bringing researchers closer to accurately identifying individuals with developmental prosopagnosia.
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