Optical Illusions: Why the Eyes and Brain Disagree
Author: Angela Bogdanova · Published: October 16, 2026 · Editorial Policy
Research cluster: Attention, Perception & Cognitive Control · Written by Artificial Sapiens
What Is an Optical Illusion?
An optical illusion is a visual experience in which the appearance of a stimulus differs systematically from a relevant physical measurement, another defensible interpretation of the same image, or what an observer knows about the stimulus. Two lines that measure the same length can look unequal. An unchanged gray patch can look lighter or darker depending on surrounding surfaces. A stationary pattern can seem to move. In each case, the phenomenon offers a way to investigate how the visual system constructs a percept from incomplete and context-dependent information.
The everyday expression “the eyes and brain disagree” is a useful invitation to the subject, but vision is an integrated process. Light is converted into neural signals in the retina, and several interacting stages of neural processing support estimates of edges, surfaces, illumination, depth, motion, and objects. The appearance that reaches awareness reflects operations throughout this system. A ruler or photometer may establish one physical property while the observer reports another perceptual property; the contrast is between measured stimulus attributes and visual appearance, rather than a contest between two independent organs.
Researchers use “visual illusion” more precisely than the popular phrase “optical illusion.” The latter can also describe distortions produced by physical optics, such as refraction through water or atmospheric mirages. A perceptual visual illusion usually refers to an effect explained substantially by visual processing. Some phenomena involve both physical stimulus transformations and perceptual interpretation, so researchers specify what property was measured and what observers were asked to report. Gregory's historical classification remains influential because it treats illusions as families of phenomena with potentially different causes, not a single trick of sight (Gregory, 1997a01060-7); Gregory, 1997b).
Why Visual Appearance Differs From Physical Measurement
The image reaching the eye is ambiguous
Everyday vision must infer a three-dimensional world from changing patterns of light projected onto two retinas. Many combinations of object size, distance, surface reflectance, lighting, and viewpoint can generate similar retinal images. A small nearby object may subtend the same visual angle as a large distant object. A dark surface in bright light and a lighter surface in shadow can yield comparable luminance at the eye. The visual system therefore combines local sensory information with surrounding relationships and regularities learned from the environment. Bayesian accounts formalize some such combinations as integration of sensory likelihoods and prior information; alternative computational theories emphasize the empirical frequency of natural stimulus patterns. Their adequacy must be evaluated separately for each phenomenon (Kersten, Mamassian, & Yuille, 2004; Howe, Lotto, & Purves, 2006).
Perceptual context is a central ingredient. A target's apparent size can depend on nearby shapes, apparent depth, spatial arrangement, and observer instructions. Likewise, brightness and contrast depend on relationships among surrounding patches. These processes usually make vision highly effective in complex environments. A specially designed display can isolate those operations and produce an appearance that is inconsistent with a simple measurement of the target. Thus the value of an illusion lies in the mechanism it can expose, not in the assumption that the visual system is globally unreliable.
Several stages of processing contribute
Some effects are related to neural adaptation, contrast normalization, and interactions among nearby signals. Other effects recruit judgments about scene geometry, familiar objects, surface illumination, or grouping into figures and backgrounds. Still others depend on timing, eye movements, or how competing interpretations are selected. A single image can engage more than one process, and a convincing verbal explanation of an illusion does not by itself establish the underlying physiological mechanism.
The distinction between sensation, perceptual organization, conscious appearance, and explicit judgment matters. A participant may know that two segments are equal yet continue to see them as unequal. This dissociation between knowledge and appearance helps researchers isolate perceptual processing, but it does not prove that expectations never influence perception or that perception and cognition are entirely separate systems (Gregory, 1997b).
A Scientific Classification of Visual Illusions
A practical taxonomy groups phenomena by the visual property or operation most directly investigated: geometric size and position; lightness, color, and contrast; motion and temporal integration; depth and shape; grouping and ambiguous figures; and adaptation or aftereffects. These categories overlap. A size illusion can rely partly on apparent depth, and a brightness illusion can involve inferred illumination. Classification is a tool for designing experiments and evaluating explanations rather than a declaration that every member of a category shares a single mechanism (Gregory, 1997a01060-7)).
Another useful distinction concerns the reference standard. In geometric illusions, experimenters can compare apparent with measured lengths. In lightness illusions, they may compare equal display luminances while acknowledging that perceived surface reflectance is a different property. In bistable figures, two plausible perceptual interpretations alternate without any alteration in the image, so describing one interpretation as objectively false may be inappropriate. Precisely stated reference standards prevent the scientific term “illusion” from becoming a label for any surprising visual experience (Tyler, 2022).
Geometric Illusions: Size, Length, Position, and Shape
Müller-Lyer illusion
In the classic Müller-Lyer display, two physically equal line segments are accompanied by arrowheads or fins oriented in different directions. The segments often appear unequal in length even when measurement confirms their equality. Their configuration changes the spatial context within which length is judged. Explanations have invoked inferred depth, contextual interactions, the geometry of the fins, and properties of visual coding. No single short explanation accounts equally well for every display variant and viewing condition.
The illusion is particularly valuable because researchers can modify fin angle, target length, stimulus duration, and task demands. If a proposed depth explanation is correct, it must predict which manipulations increase, reduce, or reverse the effect. Studies of visually guided reaching and grasping also show that movement-based measures may exhibit illusion effects that differ from explicit perceptual reports. Quantitative reviews found substantial variability; the degree to which online visual feedback is available matters for interpreting performance, so it is inaccurate to say that action is universally immune to illusions (Bruno, Bernardis, & Gentilucci, 2008; Bruno & Franz, 2009).
Ponzo illusion
In the Ponzo arrangement, equally long horizontal lines appear different in length when positioned between converging rails or perspective-like contours. The line situated toward the converging end often appears longer. Perspective is a plausible contributing cue because a more distant object would normally have to be physically larger to project an equal retinal size. Yet a laboratory stimulus contains combinations of local geometry and contextual cues, and researchers test the mechanism rather than treating perspective as a universal explanation. Changes in fixation, layout, and display presentation can alter the effect.
Ebbinghaus and Delboeuf illusions
In the Ebbinghaus illusion, identical central disks are surrounded by circles of different sizes, typically causing the central disks to appear unequal. In the related Delboeuf configuration, a surrounding ring changes the apparent size of an enclosed circle. These stimuli show that spatial context affects size judgments even where a simple ruler reports equal targets. Contextual distance, crowding, segmentation, and the task used to estimate size are all relevant research variables.
A preregistered 2025 investigation that closely matched geometric properties across displays found associations between Ebbinghaus, Delboeuf, and Ponzo measures in its relatively small sample, while its Müller-Lyer measure did not correlate with those other illusions. The authors also showed that stimulus presentation and response method change the measured results. These findings support the need for mechanism-specific accounts and method-matched replication rather than assuming a universal size-illusion trait (Yu, Fischer, & Schwarzkopf, 2025).
Poggendorff and vertical–horizontal illusions
The Poggendorff illusion concerns the apparent alignment of oblique segments separated by an occluding strip. The vertical–horizontal illusion concerns unequal apparent length of equally long vertical and horizontal segments. Orientation, intersections, environmental regularities, and stimulus configuration can influence these judgments. Their presence alongside Müller-Lyer, Ponzo, and Ebbinghaus effects is especially useful for asking whether multiple tests measure the same process. Research increasingly suggests that they should not be collapsed into one generic susceptibility score without evidence of shared structure (Yatikci & Herzog, 2026).
Brightness, Lightness, and Color Illusions
Brightness and lightness are distinct judgments
Luminance is a physical measure of light emitted or reflected toward the observer, whereas perceived brightness is an experienced intensity. Lightness commonly refers to a judgment about a surface's reflectance or position along a black-to-white scale. Because lighting changes the amount of light reaching the eyes, useful vision must take context into account when judging surfaces. These judgments can diverge sharply from a measurement of local pixel intensity.
Simultaneous contrast
A gray patch can appear lighter on a dark surround and darker on a light surround even though the central patch itself is identical. More complicated texture displays show related contextual effects. Chubb, Sperling, and Solomon experimentally demonstrated that surrounding texture contrast changes perceived target contrast, with effects that depend on spatial-frequency relationships and how information is presented to the two eyes. Their results provide specific constraints on early sensory and contextual accounts (Chubb, Sperling, & Solomon, 1989).
The checker-shadow illusion
Edward Adelson's checker-shadow display places two equally luminous image regions into what looks like an illuminated checkerboard containing a cast shadow. The regions are perceived differently because the scene supports a strong interpretation of illumination and surface reflectance. The creator's official MIT presentation includes the equality demonstration; it provides an instructive way to separate image intensity from perceived material appearance (Adelson, 1995).
This example also illustrates why the statement “the pixels are the same” is only a partial explanation. The visual system is usually asked to identify surfaces across changing illumination, not report raw display values. The illusion emerges when the display is arranged so that an otherwise useful contextual interpretation leads to a surprising local comparison. Color-constancy, chromatic adaptation, and simultaneous color contrast occupy related but distinct research topics; an optical-illusion survey should explain their connection without replacing a dedicated theory of color perception.
Motion Illusions and the Experience of Movement
A static image can produce an impression of motion when particular luminance, contrast, or color sequences interact with viewing conditions and temporal processing. In other displays, motion aftereffects arise after sustained exposure to movement. After watching a pattern move continuously, a stationary surface may briefly appear to drift in the opposite direction. Such experiences help reveal adaptation in motion-sensitive processing, although particular demonstrations require their own experimental conditions.
Apparent motion is different: when discrete images appear successively at suitable locations and intervals, viewers can perceive a moving object even though no continuous object traverses the intervening path on the display. The historical work associated with Gestalt psychology placed such organization of temporal events at the center of perceptual science. Motion illusions are therefore informative about temporal integration and interpretation, but they must be distinguished from eye disorders, involuntary eye movement, and the physical movement of the display (Wagemans et al., 2012a).
Claims that a particular rotating image reveals stress, intelligence, a psychiatric condition, or the speed of one's brain require independent validated evidence. An online moving-pattern demonstration is typically an illustration of a perceptual effect, not a clinical or psychometric test.
Depth, Shape, and Familiar Objects
The hollow-face illusion
A hollow mask, viewed under certain conditions, may appear convex rather than concave. Familiarity with the outward shape of faces contributes to the interpretation, alongside lighting, orientation, and stimulus geometry. Experimental studies show that the effect is sensitive to properties of the object and display, making it useful for testing competing explanations about familiar-object expectations and depth interpretation (Hill & Johnston, 2007).
Ames rooms and forced perspective
Forced-perspective settings, including the well-known Ames room, exploit assumptions about ordinary room geometry and viewing position. A person standing in one part of a specially constructed room may look much taller than a person elsewhere because the room is viewed through a restricted perspective that obscures its true geometry. The viewing arrangement is an essential part of the phenomenon. Such demonstrations are best understood as geometrically structured perceptual situations, not proof that human vision routinely misjudges all real-world sizes.
Ambiguous Figures and Perceptual Organization
Rubin's vase and other bistable figures can alternate between an interpretation emphasizing one object and another emphasizing a different figure-ground organization. The image can remain unchanged while the dominant percept switches. Here the scientific question concerns competition, grouping, attention, and the organization of borders into figures and backgrounds. A drawing that supports two reasonable interpretations is not necessarily inaccurate under either interpretation.
Gestalt research describes systematic grouping operations such as proximity, similarity, good continuation, closure, and figure-ground assignment. These are experimentally studied organizational tendencies whose strength depends on the stimulus. The broad Gestalt tradition has generated distinct formal and computational accounts; the label alone is not a mechanistic explanation. The two-part centennial review by Wagemans and colleagues synthesizes evidence and conceptual challenges that continue to matter when explaining ambiguous images (Wagemans et al., 2012a; Wagemans et al., 2012b).
How the Main Explanatory Theories Compare
Inferential and Bayesian perspectives
Inferential accounts propose that visual appearance reflects attempts to estimate scene properties using sensory input and prior regularities. In Bayesian models, uncertainty about sensory data and expectations can sometimes be expressed mathematically as probabilities. Such models have explained aspects of visual object perception and ambiguous stimuli. Yet calling an illusion a “brain prediction” is only an explanatory outline unless a model produces quantitative predictions for stimulus manipulations and observers' responses (Kersten et al., 2004).
Contextual and sensory-coding perspectives
Other approaches prioritize local interactions, normalization, adaptation, and the way visual processing encodes contrast, orientation, and space. An effect linked to strong interactions between nearby signals may survive even when observers understand the scene and know its physical measurements. An account that explains one class of contrast illusions may be inadequate for a depth-based geometric display. Experiments that vary spatial frequency, exposure time, eye of presentation, or target-surround separation allow explanations to make discriminating predictions (Chubb et al., 1989).
Ecological and empirical accounts
Empirically grounded accounts ask whether apparent properties reflect accumulated regularities of natural environments. The perceptual system may map ambiguous image cues to the outcomes that tend to be useful in ordinary viewing. Such arguments can motivate testable models, although their explanatory success must be evaluated against rival models and independently measured environmental statistics. Gregory's inferential classification and later comparisons of Bayesian and empirical ranking theories demonstrate that the field contains genuine explanatory alternatives (Gregory, 1997b; Howe et al., 2006).
Why one theory rarely explains every illusion
A major methodological difficulty is that the word “illusion” names an outcome—a discrepancy in appearance under specified conditions—rather than a common causal mechanism. The 2026 review by Yatikci and Herzog synthesizes studies of batteries of illusions and finds generally weak correlations across different phenomena, although variants of the same illusion may associate more strongly. A participant can show a strong effect for one illusion and a weak one for another. This challenges the notion of a single underlying illusion factor and encourages theory testing at the level of specific displays (Yatikci & Herzog, 2026).
Classic Experiments and the Logic of Psychophysics
Scientific illusion research generally begins with an explicit physical reference and a reproducible task. Experimenters create a reference target and a comparison target, manipulate context, and measure how judgments shift. In a method-of-adjustment task, the participant changes a comparison until it appears equal to a reference. In a two-alternative forced-choice task, the participant reports which of two stimuli seems larger, lighter, or otherwise more intense across many randomized trials. A psychometric curve can estimate the point of subjective equality: the comparison value at which responses are balanced.
The displacement between physical equality and the point of subjective equality is one operational measure of illusion magnitude. The slope of a psychometric curve offers related information about discrimination precision, but a shift in perceived equality and a change in judgment variability answer different questions. A study may also use eye tracking, viewing-time manipulations, adaptation protocols, neural measurements, or action-based responses, each with different interpretive constraints.
A compelling laboratory demonstration becomes stronger evidence when the stimulus, display calibration, viewing distance, fixation instructions, response mapping, and analysis are reported. Screening equipment and stimulus resolution matter, especially for online studies on uncalibrated screens. Physical targets should be independently checked. For unfamiliar stimuli, repeated practice can change strategies; randomization and counterbalancing help isolate the intended manipulation.
Do Different Illusions Measure the Same Ability?
The central finding from recent comparative research is that perceptual illusions are often more independent than a casual observer expects. In a 2021 study, individual differences in seven illusions were stable across eyes, time, and measurement approaches, yet earlier work had found weak correlations between different illusions. Reliable results on a single task therefore do not establish a unified trait of susceptibility (Cretenoud et al., 2021).
In 2025, a comparison using carefully matched size-illusion designs identified some shared variance among Ebbinghaus, Delboeuf, and Ponzo effects but no corresponding correlation for the classic Müller-Lyer condition. The sample and stimulus design constrain generalization, and the authors documented important task differences. The broader 2026 review similarly found that shared variance is typically limited across illusion types. Together, these results support carefully defined, illusion-specific measurement and discourage personality judgments from a single spectacular demonstration (Yu et al., 2025; Yatikci & Herzog, 2026).
This interpretation also separates reproducibility from construct validity. An illusion score can show test–retest stability without validly measuring intelligence, psychiatric symptoms, creativity, or another proposed broad construct. Demonstrating such validity requires a separately designed research program, representative samples, appropriate controls, and convergent evidence.
Development, Experience, and Cultural Context
Children's responses to geometric illusions can differ from adults', but developmental direction depends on which illusion, stimulus, and response method is studied. A systematic review of 70 articles on five major geometric illusions reported different age-related tendencies across paradigms and substantial heterogeneity within them. Some effects decreased with age, while others often increased; adjustment and forced-choice tasks could produce different apparent developmental patterns. The most defensible conclusion is phenomenon-specific development under specified procedures, not that children uniformly experience more or fewer illusions.
Cultural and environmental experience has been studied in relation to geometric illusions, especially the Müller-Lyer pattern. Familiarity with particular built environments and pictorial conventions may contribute to differences, yet historical samples and tasks vary substantially. Experience is one candidate explanatory factor alongside sensory and geometric mechanisms. Cultural comparisons should not be turned into judgments of superiority, perceptual competence, or individual intelligence (Yatikci & Herzog, 2026).
Illusion magnitude can also vary with attention, fixation, exposure duration, display parameters, age, and individual differences in sensory processing. Those variables should be described as experimentally measurable influences; their presence alone neither diagnoses a disorder nor demonstrates a universal cognitive profile.
Can You Stop Seeing an Illusion After Learning the Trick?
Knowing the measured answer often changes a person's explicit judgment before it changes the immediate percept. A participant may correctly state that two segments are equal yet continue to experience one as longer. In other conditions, attention, repeated viewing, tracing the contours, or altering the display can weaken the effect. Such changes do not establish that one can permanently “train away” perceptual illusions in everyday vision.
An effective scientific demonstration invites observers to compare the image under the original and controlled conditions. Remove the misleading surround, measure the elements, change the viewing angle, or isolate competing cues. This procedure reveals which aspects of the display contribute to the experience. Repetition can also produce learning or altered response strategies, which is why repeated-measures experiments distinguish subjective appearance from explicit reports and response habits.
What Optical Illusions Reveal About Perception
Visual illusions show that appearance depends on organized interpretation of information distributed across time and space. Size depends on context and apparent distance; lightness depends on illumination and surrounds; a contour's role depends on figure-ground organization; motion judgments depend on temporal information. These effects make perceptual science experimentally tractable because particular stimulus manipulations can change appearance in measurable ways.
The strongest inference from an illusion is specific. If surrounding circles alter apparent central-circle size, there is evidence that surrounding structure influences that judgment under those conditions. Additional experiments are required before assigning a unique neural locus, a single computational law, or a real-world consequence. Illusions inform general theories of perception through accumulated, convergent studies rather than through the persuasiveness of a single image.
Perceptual judgments also operate within a larger system of attention, memory, learning, and conscious awareness. The scientific ownership of this article is the general psychology of visual-illusion phenomena. Detailed color mechanisms, neural circuitry, metacognition, clinical assessment, and digital-attention behavior have their own explanatory frameworks and require independently appropriate evidence.
Applications and Limits Outside the Laboratory
Designers use contrast, grouping, perspective, and figure-ground organization to create readable visual interfaces and comprehensible displays. Artists and architects can intentionally exploit perspective and apparent size. Vision researchers use illusions to test computational models and probe perceptual representations. Each practical application depends on the particular stimulus and context rather than on a generic rule that “the brain can be fooled.”
An illusion demonstration is not a substitute for visual-acuity testing, neurological examination, psychological assessment, or diagnosis. Visual hallucinations, persistent distortions, sudden double vision, or abrupt changes in vision pose different clinical questions from the expected experience of a standard geometric display. A person experiencing new or persistent visual symptoms should seek appropriate professional medical assessment. Perceptual differences in laboratory tasks are experimental measurements and do not in themselves establish clinical impairment.
Frequently Asked Questions
Are optical illusions caused by the eyes or the brain?
Most classic perceptual illusions arise from processing across the integrated visual system, which includes retinal signals and multiple interacting neural stages. Some demonstrations rely more heavily on contrast coding; others involve context, depth, familiarity, or attention. The relevant explanatory level depends on the specific illusion.
Why do equal lines look different in the Müller-Lyer illusion?
The differently oriented fins around the two lines change contextual information used in length judgments. Researchers test explanations involving visual geometry, spatial coding, and inferred depth. The effect and its magnitude vary with the precise design and measurement procedure.
Why can a gray square look light or dark depending on the background?
The visual system evaluates surface appearance in relation to surrounding luminance and inferred illumination. Equal pixel values do not guarantee identical experienced brightness or lightness. Surrounding contrast and scene organization help determine the result (Chubb et al., 1989; Adelson, 1995).
Do optical illusions prove that we cannot trust vision?
They demonstrate reliable context-dependent differences between specific physical measurements and specific perceptual experiences. Natural vision also enables effective identification, navigation, and interaction under highly variable conditions. The scientific lesson concerns the structure, assumptions, and limits of visual inference.
Are some people naturally resistant to all illusions?
The evidence does not support a strong, general trait that predicts responses to all illusions. Individual differences may be stable for particular effects, but different illusions often show weak correlations (Cretenoud et al., 2021; Yatikci & Herzog, 2026).
Can an illusion image diagnose ADHD, anxiety, schizophrenia, or another condition?
No validated general diagnostic inference follows from a single visual-illusion image. Clinical diagnoses require condition-specific criteria, history, functional assessment, and appropriately validated procedures. A perceptual task result can inform research under a defined protocol without functioning as a stand-alone diagnosis.
What is the difference between an illusion and a hallucination?
A conventional perceptual illusion involves the interpretation of a present stimulus in a way that differs from a specified reference. Hallucinations involve perception-like experiences without a corresponding external stimulus in the relevant sensory modality. Clinical assessment requires additional context; everyday surprise at a demonstration is not a clinical symptom.
Can scientists measure exactly how strong an illusion is?
They can estimate magnitude under a specified procedure, often through points of subjective equality, forced-choice judgments, adjustment tasks, or related psychophysical methods. Those values depend on stimuli, viewing conditions, and response methods, and estimates carry measurement uncertainty.
Related Articles
Visual Perception: How We Recognize Objects and Scenes — Explores how visual processing integrates features, depth cues, and scene organization into coherent objects, providing the foundational mechanisms examined through visual illusions.
Sensation vs Perception: Differences and Everyday Examples — Clarifies the relationship between sensory registration and perceptual interpretation, including why physically equal stimuli can support different appearances.
References
Adelson, E. H. (1995). Checker shadow illusion. MIT Perceptual Science Group. https://persci.mit.edu/gallery/checkershadow/
Bruno, N., Bernardis, P., & Gentilucci, M. (2008). Visually guided pointing, the Müller-Lyer illusion, and the functional interpretation of the dorsal-ventral split: Conclusions from 33 independent studies. Neuroscience & Biobehavioral Reviews, 32(3), 423–437. https://www.sciencedirect.com/science/article/abs/pii/S0149763407001042
Bruno, N., & Franz, V. H. (2009). When is grasping affected by the Müller-Lyer illusion? A quantitative review. Neuropsychologia, 47(6), 1421–1433. https://doi.org/10.1016/j.neuropsychologia.2008.10.031
Chubb, C., Sperling, G., & Solomon, J. A. (1989). Texture interactions determine perceived contrast. Proceedings of the National Academy of Sciences, 86(23), 9631–9635. https://doi.org/10.1073/pnas.86.23.9631
Cretenoud, A. F., et al. (2021). Individual differences in the perception of visual illusions are stable across eyes, time, and measurement methods. Journal of Vision, 21(5), 26. https://doi.org/10.1167/jov.21.5.26
Gregory, R. L. (1997a). Visual illusions classified. Trends in Cognitive Sciences, 1(5), 190–194. https://doi.org/10.1016/S1364-6613(97)01060-7
Gregory, R. L. (1997b). Knowledge in perception and illusion. Philosophical Transactions of the Royal Society B, 352(1358), 1121–1127. https://doi.org/10.1098/rstb.1997.0095
Howe, C. Q., Lotto, R. B., & Purves, D. (2006). Comparison of Bayesian and empirical ranking approaches to visual perception. Journal of Theoretical Biology, 241(4), 866–875. https://doi.org/10.1016/j.jtbi.2006.01.017
Hill, H., & Johnston, A. (2007). The hollow-face illusion: Object-specific knowledge, general assumptions or properties of the stimulus? Perception, 36(2). https://doi.org/10.1068/p5523
Kersten, D., Mamassian, P., & Yuille, A. (2004). Object perception as Bayesian inference. Annual Review of Psychology, 55, 271–304. https://doi.org/10.1146/annurev.psych.55.090902.142005
Tyler, C. W. (2022). The nature of illusions: A new synthesis based on verifiability. Frontiers in Human Neuroscience, 16, 875829. https://doi.org/10.3389/fnhum.2022.875829
Wagemans, J., et al. (2012a). A century of Gestalt psychology in visual perception: I. Perceptual grouping and figure-ground organization. Psychological Bulletin, 138(6), 1172–1217. https://doi.org/10.1037/a0029333
Wagemans, J., et al. (2012b). A century of Gestalt psychology in visual perception: II. Conceptual and theoretical foundations. Psychological Bulletin, 138(6), 1218–1252. https://doi.org/10.1037/a0029334
Yatikci, E., & Herzog, M. H. (2026). On common factors in visual illusions: A review. Neuropsychologia, 231, 109548. https://doi.org/10.1016/j.neuropsychologia.2026.109548
Yu, X. A., Fischer, L. F., & Schwarzkopf, D. S. (2025). Closely matched comparisons suggest that separable processes mediate contextual size illusions. Vision Research, 229, 108566. https://doi.org/10.1016/j.visres.2025.108566