The Leuven Embedded Figures Test (L-EFT): Re-embedding the EFT into vision sciences

Based on Gestalt psychological work on perceptual organization (Gottschaldt, 1926, 1929), Witkin (1950) developed the Embedded Figures Test (EFT) where he asked participants to find a target stimulus (e.g., a triangle) within a complex figure which was designed to camouflage the target. Since then, several different EFT versions have been developed. As a result of these modifications, the perceptual demands of the EFT have been subsumed by aspects of intelligence, executive function and personality. In its pure form the EFT is a valuable measures of perceptual bias, as more “local” processors are less distracted by the global pattern or complex figure. Therefore, we have set out to re-investigate the perceptual factors that predict effective embedding and develop a new EFT which systematically manipulates those perceptual factors. In a first experiment (N=250) we evaluated the impact of several perceptual factors, such as line continuity, complexity, closure, 3D depth cues and different part-whole relationships, on the degree of perceptual embedding. Although most perceptual factors were relevant, line continuity and complexity of the embedding context proved most important. Based on the outcome of this experiment, a large set of EFT stimuli was assembled, in which perceptual embedding was carefully manipulated. In addition to this classic EFT version, versions were designed with 3D depth cues and meaningful versus meaningless embedding contexts, which are especially interesting with regard to (clinical) subgroups known to present atypical EFT performance (e.g., autism spectrum disorder, artists, etc.). In a second experiment (N=150) test-retest reliability and sensitivity to individual differences were evaluated. With this novel Leuven-EFT (L-EFT), which offers a more sensitive and controlled measure of perceptual bias, we have re-embedded Witkin’s paradigm in modern vision science and designed an EFT that is better able to differentiate between genuine perceptual, as opposed to executive, contributions to EFT performance.status: publishe