Creating a Visual Illusion Based on Contrast: Continuing with a Visual Illusion Experiment – Part 7


In previous posts in the series we have looked at reproducing an illusion (see Appendix). Whilst the original illusion was not reproduced there were a few interesting learning points along the way. The effects were very subtle and modifying the brightness and other variables didn’t impact too significantly on these effects. After watching the video below it became immediately obvious that the image developed in the previous posts could be modified to produce a convincing illusion. By inserting the words ‘contrast’ and ‘illusion’ into the circle above the reader may be convinced that the letters at the end of the words appear lighter than the letters at the beginning of the words. All the letters are of course of a similar colour and the effect results from the contrast with the background which is graded.

The contrast effect may be explained by firing in a subgroup of Ganglion cells at the stage of retinal processing as discussed in the talk by Professor Markus Meister below.


Explaining the Neurobiology of Illusions – A Talk from Caltech

Do Cats See Illusions Too?

A Visual Illusion Experiment – Part 6

A Visual Illusion Experiment – Part 5

A Visual Illusion Experiment – Part 4

A Visual Illusion Experiment – Part 3

A Visual Illusion Experiment – Part 2

A Visual Illusion Experiment – Part 1

Index: There are indices for the TAWOP site here and here Twitter: You can follow ‘The Amazing World of Psychiatry’ Twitter by clicking on this link. Podcast: You can listen to this post on Odiogo by clicking on this link (there may be a small delay between publishing of the blog article and the availability of the podcast). It is available for a limited period. TAWOP Channel: You can follow the TAWOP Channel on YouTube by clicking on this link. Responses: If you have any comments, you can leave them below or alternatively e-mail Disclaimer: The comments made here represent the opinions of the author and do not represent the profession or any body/organisation. The comments made here are not meant as a source of medical advice and those seeking medical advice are advised to consult with their own doctor. The author is not responsible for the contents of any external sites that are linked to in this blog.


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