Modeling visual hallucinations


8 Responses to “Modeling visual hallucinations”

  1. Anonymous says:

    I personally have these types of hallucinations from time to time. They are in the spiral category and seem to rotate CCW as the spiral extends away from me. It strobes and changes colors rapidly like the new light bars on a police car and interferes with my vision, as I cannot focus on anything. I tend to rely on my peripheral vision to navigate and take an nap. Once a little bit rested, it goes away.

  2. AirPillo says:

    I’ve always wondered why pressing on one’s eyes caused such hallucinations, after discovering the effect as a kid (and promptly being warned not to do that to my eyes).

  3. Yenzo says:

    Please, please get your psychology right. Your articles on the DSM-V and evolutionary psych weren’t good, and confusing hallucinations with illusions is downright terrible. For future reference: A hallucination means that no stimulus is given. Confusing the senses with ambiguous stimuli is called an illusion.

    • Andrea James says:

      @Yenzo#3: The title of Dr. Cowan’s speech would indicate that hallucination is the correct term here, not illusion. Did you watch it before attempting to correct me?

      • Yenzo says:

        I did not watch the speech and I apologize if my criticism was not justified. With the pictures you used and the mentioning of Klüver, etc. I was quite sure that you were talking about illusions, so your post was at least a bit ambiguous in that regard.

        My criticism of your other articles still stands, however, and I’m sorry that I won’t have the time to discuss it in detail. Suffice to say there are some researching psychologists out there in whose opinion you are oversimplifying to the point of misrepresentation.

  4. Ambiguity says:

    He conducted a range of self-experiments using peyote in a lab setting, recording as much subjective and objective data as he could while high.

    Man, why do I never see adverts for such cool jobs? Here I am stuck in front of a computer…

  5. Rich Keller says:

    A few years ago I found an article by Susan Carr on entoptic phenomena that categorized phosphenes.
    It’s at It doesn’t look like Carr had cited Dr. Cowan’s work, however.

    After looking at loads of similar motifs from different times and cultures across the world, I’d had a hunch that the motifs were caused by something from our physiology or a by-product of it at least.

  6. Microship says:

    I did a little work on exactly this in 1982, when I was hobnobbing at AI conferences and thinking a lot about the rotation and scaling problem that was confounding real-world use of the spatial FFT. Someone had just laboriously discovered the logarithmic polar mapping between retina and primary visual cortex, and I modeled it (very crudely) on my Cromemco Z2D. The results were quite exciting, and for a time I was trying to fashion a “preprocessor” for visual pattern recognition along these lines, even imagining a screw-on fiber-optic adapter to do it in parallel… given the slow computers of the day.

    Here’s a short summary with a couple of pictures demonstrating the mapping:


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