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Müller-Lyer Illusion in Adults Increases with Age but Is Not Affected by Mild Visual Acuity Loss
Bichi Chen1, Na Lin1, Li Tian1
1National Clinical Research Center for Ocular Diseases, Eye Hospital, Wenzhou Medical University, Wenzhou, People's Republic of China.
Purpose:
To investigate the impact of mild visual acuity loss on the Müller-Lyer illusion in adults and evaluate its potential as a clinical indicator for visual-cognitive integration mechanisms.
Methods:
Three experiments were conducted. Experiment 1 measured illusion intensity in 49 young adults (25.08 ± 3.38 years) before and after inducing transient visual acuity loss (0.40 logMAR) via Bangerter occlusion foils. Experiment 2 compared 26 cataract patients (65.19 ± 3.87 years) with 59 age-matched controls (63.98 ± 5.57 years). Experiment 3 tracked 14 cataract patients (69.50 ± 6.14 years) pre- and post-surgery. Illusion intensity was quantified using a two-alternative forced-choice task.
Results:
Illusion intensity remained stable across conditions: no differences were observed before /after wearing occlusion glasses (4.33% vs 3.75%, p = 0.141), between cataract patients and controls (8.79% vs 8.20%, p = 0.301), or pre-/post-surgery (9.46% vs 9.87%, p = 0.357). However, normally-sighted elderly participants exhibited stronger illusions than young adults (8.20% vs 4.33%, p < 0.001). Multivariate regression confirmed age as the sole predictor of illusion intensity (β = 0.088, p = 0.001), independent of visual acuity.
Conclusion:
The intensity of Müller-Lyer illusion in adults is modulated by age but resistant to mild visual acuity loss, implicating its utility in studying visual-cognitive integration.
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