About this project
Chasing the Dot: Art, Stroboscopic Light, and the Science of Inner Vision
Chasing the Dot (2021) by Philip Vermeulen belongs to a long tradition in which artists have used flickering light not simply as illumination, but as a medium capable of generating visual experiences within the observer. Presented with an intense sequence of coloured stroboscopic light projected onto a large screen, visitors may perceive vivid colours, textures, movements, and geometric formations that are not physically present in the stimulus. In the scientific literature, such phenomena are described as stroboscopically induced visual hallucinations (SIVHs; Hewitt et al. 2025).
The installation also produces the more specific phenomenon from which it takes its name. A small dot may appear close to the centre of vision and seem to move whenever the observer shifts their gaze. The effect probably involves differential adaptation of photoreceptors in and around the fovea, producing an afterimage that remains anchored to the centre of the visual field. Because this afterimage moves with the eyes rather than remaining attached to the screen, the dot appears to evade the observer. This illustrates how Chasing the Dot transforms basic properties of the visual system into an artistic experience.
The scientific study accompanying Chasing the Dot continues a history in which stroboscopic artworks, devices, and public installations have repeatedly attracted researchers interested in documenting the unusual experiences they produce. Visitors are invited to draw what they saw and to complete questionnaires assessing both their perceptual experience and selected personality characteristics, particularly the vividness and controllability of visual mental imagery and openness to experience. The study asks whether the considerable differences between individual experiences are systematically related to comparatively stable characteristics of the observers.
From introspective experiments to stroboscopic art
The interaction between flickering light, visual experience, and scientific observation predates the invention of the electronic stroboscope. In 1819, the physiologist Jan Evangelista Purkinje described looking towards a candle with closed eyes while moving his hand across the light. The intermittent illumination generated colourful geometric patterns, which he documented in drawings. David Brewster subsequently investigated related phenomena and noted that their appearance varied with the frequency of stimulation (Purkinje 1819; Brewster 1834). Drawings were therefore present at the very beginning of research into flicker-induced visual phenomena: they provided a means of externalising experiences that were otherwise private and difficult to describe.
Scientific interest increased with the development of electroencephalography. During the 1940s and 1950s, flashing light was used to investigate how rhythmic stimulation affected electrical brain activity. William Grey Walter observed that participants exposed to stroboscopic light reported vivid colours, spirals, lattices, and other moving patterns, even though the light itself contained none of these structures (Walter 1953). Researchers including John Smythies subsequently asked participants to describe and draw their experiences, producing classifications of recurrent geometric forms and movements (Smythies 1959a, 1959b).
At approximately the same time, flicker moved from the laboratory into art and counterculture. After encountering flickering sunlight through trees, the artist and writer Brion Gysin developed the Dreamachine with Ian Sommerville. The device consisted of a perforated rotating cylinder placed around a light source. Viewed with closed eyes, it produced rhythmic illumination and vivid internally generated imagery. Because it could be constructed from relatively simple materials, the Dreamachine circulated through artistic and literary communities and influenced figures including William Burroughs, Allen Ginsberg, Keith Haring, and several prominent musicians (Geiger 2004; Hoptman 2010; Hewitt et al. 2025).
Experimental filmmaker Tony Conrad developed a different artistic use of the same phenomenon. His film The Flicker (1966) consisted primarily of alternating black and white frames, with the temporal structure of the film controlling the frequency and duration of stimulation. Rather than representing hallucinations on screen, the film used the projector and the observer's visual system to produce them. Conrad also combined changing flicker sequences with sound, anticipating contemporary installations in which light, rhythm, spatial arrangement, and music jointly shape the experience.
This relationship between artistic experimentation, technological development, and scientific investigation has continued as electronically controlled light systems have become more flexible. Contemporary stroboscopic-light systems are developed by companies including Light Attendance, LLUMA, Lumenate, and SerenSpecs, several of which maintain links with scientific research.
Collective Act's 2022 Dreamachine provided another large-scale artistic context in which scientists subsequently investigated the experiences produced. Visitors were invited to draw what they had seen, resulting in a dataset of 10,598 drawings. A recent computer-vision analysis found that geometric patterns predominated but also identified less commonly documented formations, including concentric squares, crosses, astroid-like figures, and fourfold rotational symmetries (Grove et al. 2026). Related work has developed image-recreation methods for experimentally induced hallucinations (Hewitt et al. 2026a), a questionnaire for characterising visual hallucinatory content (Hewitt et al. 2026b), and computational methods for analysing open-ended reports from the installation (Beauté et al. 2026).
This growing international exchange was reflected in the Berlin Symposium on Stroboscopic Light 2026, organised at Freie Universität Berlin by Timo Torsten Schmidt and David Schwartzman. The symposium brought together researchers, artists, and developers and included an accompanying art programme featuring Philip Vermeulen, Teun Vonk and Noortje van den Eijende, and Stratos Bichakis. A short impression of the event is available here.
Across this history, artistic and scientific approaches to stroboscopic light have operated at different speeds and scales. Artists can simultaneously manipulate frequency, intensity, colour, rhythm, sound, space, and audience interaction, often discovering new experiential effects long before these can be systematically explained. Controlled experiments necessarily proceed more slowly: they usually vary only one or a few parameters at a time in order to isolate their specific contributions. Metaphorically, artists play the instruments and explore the music they can produce, while scientists analyse the resulting sound waves. Artistic installations can therefore reveal unexpected phenomena and generate new hypotheses, whereas scientific experiments determine more precisely how and under which conditions these phenomena arise.
Studying Chasing the Dot
Our study accompanying Chasing the Dot builds directly on this lineage while applying it to a distinct artistic and perceptual situation. Unlike the closed-eye stimulation used in most contemporary flicker devices and in both historical and modern versions of the Dreamachine, Vermeulen creates an open-eye Ganzfeld-like environment. The screen remains visible, but its physical surface becomes perceptually unstable as internally generated colours, movements, geometric patterns, and afterimages interact with the external visual field.
After experiencing the installation, visitors are invited to draw the colours, patterns, movements, textures, shapes, or objects they perceived. These drawings provide an open format that does not restrict reports to predefined scientific categories. At the same time, questionnaires collect structured information about the experience and about individual characteristics of the observer. Of particular interest is whether differences in visual mental imagery—including its vividness and voluntary control—are associated with differences in the phenomena reported after stroboscopic stimulation. Openness to experience provides a further candidate trait that may relate to the richness or complexity of reported experiences.
This combination is important because the same physical installation can generate strikingly different experiences in different people. Stimulation parameters alone are therefore unlikely to provide a complete account of what a visitor sees. Individual differences in imagery, attention, expectation, and personality may contribute to how internally generated visual activity becomes conscious and how it is subsequently described or drawn. The present study cannot establish that these traits cause particular experiences, but it can identify systematic associations and generate hypotheses for subsequent controlled experiments.
Chasing the Dot thus continues more than two centuries of exchange between artistic practice and the science of perception. From Purkinje's candlelight drawings and Walter's EEG experiments to Gysin's Dreamachine, Conrad's The Flicker, contemporary light technologies, and large-scale public installations, stroboscopic light has repeatedly brought artists, scientists, developers, and audiences together around the same question: how can an apparently unstructured sequence of light generate such structured and individually distinctive worlds of experience? By combining Vermeulen's installation with drawings and psychometric measures, we extend this tradition from documenting what people see towards investigating why different observers may see different things.
References
- Beauté, R., Schwartzman, D. J., Dumas, G., Crook, J., Macpherson, F., Barrett, A. B., and Seth, A. K. (2026). “Mapping of Subjective Accounts into Interpreted Clusters (MOSAIC): Topic Modelling and LLM Applied to Stroboscopic Phenomenology.” Neuroscience of Consciousness, 2026(1), niag008. doi.org/10.1093/nc/niag008
- Brewster, D. (1834). “On the Colours of Natural Bodies.” Transactions of the Royal Society of Edinburgh, 12, 538–545.
- Conrad, T. (Director). (1966). The Flicker [Film].
- Geiger, J. (2004). Chapel of Extreme Experience: A Short History of Stroboscopic Light and the Dream Machine. Soft Skull Press.
- Grove, E. J., Hewitt, T., Seth, A. K., Macpherson, F., and Schwartzman, D. J. (2026). “A Large-Scale Computer-Vision Mapping of the Geometric Structures of Stroboscopically-Induced Visual Hallucinations.” bioRxiv. doi.org/10.64898/2026.02.18.705710
- Hewitt, T., Amaya, I., Beauté, R., Seth, A. K., Schmidt, T. T., and Schwartzman, D. J. (2025). “Stroboscopically Induced Visual Hallucinations: Historical, Phenomenological, and Neurobiological Perspectives.” Neuroscience of Consciousness, 2025(1), niaf020. doi.org/10.1093/nc/niaf020
- Hewitt, T., Grove, E. J., Seth, A. K., and Schwartzman, D. J. (2026a). “Image Recreation Methods Enable Quantitative Characterization of Geometric Visual Hallucinations.” PsyArXiv. doi.org/10.31234/osf.io/2gtsy_v1
- Hewitt, T., Seth, A. K., and Schwartzman, D. J. (2026b). “Measuring the Content of Visual Hallucinations Induced by Psychedelics and Stroboscopic Light: The Six-Dimensional Visual Hallucination Questionnaire (6D-VHQ).” PsyArXiv. doi.org/10.31234/osf.io/qv5hz_v1
- Hoptman, L. J. (2010). Brion Gysin: Dream Machine. New Museum/Merrell.
- Purkinje, J. E. (1819). Beiträge zur Kenntniss des Sehens in subjectiver Hinsicht. Johann Gottfried Calve.
- Smythies, J. R. (1959a). “The Stroboscopic Patterns.” British Journal of Psychology, 50, 106–116.
- Smythies, J. R. (1959b). “The Stroboscopic Patterns II: The Phenomenology of the Bright Phase and After-Images.” British Journal of Psychology, 50, 305–324.
- Walter, W. G. (1953). The Living Brain. W. W. Norton.