Of course we have no quantifiable measure of how well this instruction was actually followed. We settled for the less advanced solution of marking a spot in the middle of each test image and telling the test subject to try to fixate his gaze on that point, and not let his gaze wander around the image. This means we need eye tracking! We obtained a web camera and open source eye tracking software, but sadly it was too inaccurate/unreliable to be of use. This will affect our experiment! Even if we show a static simple geometrical shape to the test subject, he may move his eyes. What seems to matter is when objects move relative to the visual field, which means that when a hallucinator turns his head or even just his eyes, shifting his gaze, he will experience the tracers phenomenon across the whole visual field. Hallucinators often report a phenomenon called "tracers", where moving objects, for example a ball thrown in an arch seems to get a tail of visual patterns. The lines will be invisible when drawn, but stored on disk and can be viewed later. It will work a bit like drawing with invisible ink. Also, the computer monitor need only show the test image, it should not show the lines that the user has drawn. Basically a list of positions in space and time, telling us where the pen was located and when. Obviously we don't want to store an image, we want to store a movie.
#Hallucination experiment how to#
We bought a professional tablet (Wacom Intuos Large) and thought about how to use it for this experiment. The subject only needs to see a mouse cursor, which can be made very small and subtle in order to influence the experiment as little as possible.īut computer mice are not very nice to draw pictures with. It's better to draw on a computer screen than on a piece of paper. Also, the pen and the subject's own hand will constantly influence his OEVs as he is moving it around. The subject will see what he has drawn, which will in turn influence his OEVs and destroy the simple controlled environment. Imagine if we give the subject a paper with a simple geometric shape, a test image, and tell him to look at it and draw his OEVs. To record such data, pen and paper is insufficient. The goal is to show various geometric shapes to a test subject under controlled conditions, and let the subject draw his OEVs in real time. Three different hallucinations one drawn when staring at the center of a circle, the second drawn when staring between the center and the left edge, and the third drawn when staring at the left edge.Ī short piece of our recording, giving a glimpse of how OEVs change over time. Previous work does not seem to have investigated this input-sensitivity much. When looking at real objects in the room, or shapes on paper, the OEVs are affected and differ from the form constants. Wouldn't it be interesting to somehow see a glimpse of the motion, the dynamics, that hallucinators experience?Īlso, hallucinators often report that the classic form constants appear most clearly with closed eyes or when looking at a single-colored background. But open-eye visual hallucinations ("OEVs" from here on) are not still images, they change over time. We contribute experimental data in a form which, to our knowledge, has not existed before.Īll previous work seems to be based on still images that were drawn on paper by people hallucinating. In short, we do not add any new mathematical analysis. If you find these academic research papers too mathematical and hard to read, we recommend Mr Cowan's video lectures which are easier to digest for a layperson: Geometric visual hallucinations, Euclidean symmetry and the functional architecture of striate cortex.What Geometric Visual Hallucinations Tell Us about the Visual Cortex.Spontaneous pattern formation in primary visual cortex.Still, if you do something interesting with our data, we'd love to hear from you.
#Hallucination experiment free#
We are working on making it more accessible.Įverything is distributed under the MIT license, which basically means you're free to do whatever you want with it without asking. Requires Windows, Allegro and some programming knowledge.
#Hallucination experiment code#
Download C++ source code of the programs that record and playback data.Download raw data in csv format (76.4 MiB) - Format specification.
Watch the recorded data directly in your web browser (4.3 MiB, requires a modern browser).Our long-term goal is to analyze this data, and write a program that simulates the hallucinating brain well enough to recreate such visuals. You can freely download our recording and source code. We have recorded 9 hours of geometric visual hallucinations with a custom-made computer program and a Wacom pen & tablet.
Recording animated drawings/movies of open-eye visual hallucinations Hallucination Research Hallucination Research
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