Leuven Perceptual Organisation Screening Test

Project description

After brain injury, people can be left with difficulties in object recognition, face recognition, or reading. These abilities can be assessed with neuropsychological diagnostic test batteries of visual perception. Object recognition, however, relies on intact abilities to structure and organise the visual information coming from the eyes. We call this perceptual organisation. It includes processes like figure-ground segregation, perceptual grouping, texture perception, etc. These fundamental processes are only implicitly tested in classical tests.

The Leuven Perceptual Organization Screening Test (L-POST) fills a gap with respect to clinically oriented tests for perceptual organisation. In 15 online subtests, a range of processes are covered (see third image) . Each subtest uses a matching-to-sample paradigm where one image is shown at the top and three at the bottom (first image). A respondent needs to pick the bottom stimulus that is most similar to the one at the top. Our online test can be administered in 20-45 min. The online implementation enables us to offer a separate interface for researchers and clinicians to have immediate access to the raw and summary results for each patient and to keep a record of their patient’s entire data. Also, each patient’s results can be flexibly compared with a range of age-matched norm samples. The last image above is an example with scores in the normal range in green and scores that indicate an impairment in red.

To determine the normal range of score, we collected normative data from more than 6,000 healthy control participants. We also asked a small group of patients to perform the test twice and found consistent results between both sessions (adequate test–retest reliability). For 40 patients with brain injury, I compared performance on the L-POST with their performance on standard clinical tests of visual perception and other measures of cognitive function. The L-POST showed high sensitivity to visual dysfunction and performance was not related to other cognitive functions like memory or attention.

L-POST is freely available here.


Flemish Government – Methusalem programme


Prof Johan Wagemans – University of Leuven

Dr Lee de-Wit – University of Leuven (currently University of Cambridge)

Dr Katrien Torfs – University of Leuven (currently Vias Institute)

Run time


Associated publications

Torfs, K.*, Vancleef, K.*, Lafosse, C., Wagemans, J., & de-Wit, L. (2014). The Leuven Perceptual Organization Screening Test (L-POST), an online test to assess mid-level perception. Behavior Research Methods, 46, 472–487. https://doi.org/10.3758/s13428-013-0382-6 (* joint first authors)

Vancleef, K., Acke, E., Torfs, K., Demeyer, N., Lafosse, C., Humphreys, G. W., Wagemans, J., & de-Wit, L. (2014). Reliability and Validity of the Leuven Perceptual Organization Screening Test (L-POST). Journal of Neuropsychology, 9(2), 271-298. https://doi.org/10.1111/jnp.12050

Ding, N. & Vancleef, K. (preprint). Test-retest reliability and Practice Effect of the Leuven Perceptual Organisation Screening Test. PsyArXiv: 10.31234/osf.io/24sjt

Vancleef, K., Demeyere, N., Sun, L. (2021). Shortening the Leuven Perceptual Organisation Screening Test with Item Response Theory and Confirmatory Factor Analysis. Psychological assessment, 10.1037/pas0001045. https://doi.org/10.1037/pas0001045