Leuven Embedded Figures Test (L-EFT)
Background
The Embedded Figures Test (EFT) is a psychological and cognitive assessment tool used to measure an individual's local vs. global perceptual style. Specifically, the tests assesses how quickly participants are able to locate specific, simple shapes hidden within larger, more complex designs. The EFT was originally designed by Herman Witkin in the 1950s and has been used extensively in research on individual differences, particularly in the study of autism spectrum disorder.
The original EFT test requires physical kits and subjective stopwatch timing by a clinician. Furthermore, the procedure places heavy working memory demands on the participants as the 'local' shapes need to be kept in working memory when trying to find them in the 'global' pictures. In 2017, Lee de-Wit and colleagues at the University of Leuven published a computer-assisted publicly-available version of the EFT, called the Leuven Embedded Figures Test (L-EFT). This test not only allows the systemic manipulation of geometric shape properties such as symmetry to study exactly what makes a figure hard to find, it also isolates visual perception from confounding cognitive factors like working memory and intelligence. Instead of presenting the shapes sequentially, one-at-a time, the L-EFT confronts participants with one simple shape and several complex designs at the same time. Participants are then asked to select the one complex shape that embeds the simple one as fast as possible. Statistical analyses of L-LEFT data support that intelligence and executive functions explain less than 10% of performance variability, thus strongly suggesting that the L-EFT measures a highly specific, narrow visual skill instead (Huygelier et al, 2018).
Task Procedure
The test consists of 64 trials that test 16 shapes (4 number of lines x 2 shape types (open vs. closed) x 2 symmetry levels (sym vs. asym)) with 4 solutions each that vary in their solution complexity. The order of the 64 trials is randomly determined, as is the horizontal screen position of the three provided answer choices. Participants are asked to select the correct answer choice and submit it. Selected choices are highlighted with a blue frame and can be changed until they are submitted. There is no time-limit on responding. An optional error-correction procedure is built into the Millisecond task version. When activated, participants are asked to correct their responses, and the next trial starts only if the correct response is submitted. This procedure ensures that participants stay motivated to find the answers as only correct answers eventually end the test. A blank screen of 500ms separates each trial.
What it Measures
The Leuven Embedded Figures Test (L-EFT) measure an individual's local vs. global perceptual style
Psychological domains
- Visual Processing: Ability of the brain to interpret, make sense of, and react to the light information entering the eyes
- Part-Whole Segregation: Ability of the brain to stop seeing a cohesive "global" pattern and isolate a "local" feature.
Main Performance Metrics
- Accuracy: Proportion correct solution selections; measures response precision
- Reaction Time: Mean correct response latency (of first submission) in ms; measures speed of 'local' feature detection
Psychiatric Conditions
L-EFT performance is impaired or advanced in the following patient groups
- Autism Spectrum Disorder
- Schizophrenia
The L-EFT is a percepetual match-to-sample test and measures how fast participants can identify an embedded figure within a more complex pattern. The test manipulates several variables (such as shape symmetry and number of lines) to investigate the impact of target features on detectability.
References
Search Google Scholar for peer-reviewed, published research using the Inquisit Leuven Embedded Figures Test (L-EFT).
de-Wit, L., Huygelier, H., Van der Hallen, R., Chamberlain, R. & Wagemans, J. (2017). Developing the Leuven Embedded Figures Test (L-EFT): testing the stimulus features that influence embedding. PeerJ 5:e2862; DOI 10.7717/peerj.2862
Huygelier, H., Van der Hallen, R., Wagemans, J., De-Wit, L., & Chamberlain, R. (2018). The Leuven Embedded Figures Test (L-EFT): measuring perception, intelligence or executive function?. PeerJ, 6, e4524.
Wagner, J., Zurlo, A., & Rusconi, E. (2024). Individual differences in visual search: A systematic review of the link between visual search performance and traits or abilities. Cortex.
English, M. C., Raiter, I. M., Chen, N., Tan, D. W., Parmentier, F. B., Visser, T. A., & Maybery, M. T. (2025). Figure disembedding facility and reduced left visual field bias are linked to the social dimension of autistic traits. Attention, Perception, & Psychophysics, 1-10.