The Effect of Colour on a Contrast Illusion: Continuing with a Visual Illusion Experiment – Part 8

illusion

In a previous post we looked at how to produce the contrast illusion shown above. Simply stated the letters on the right appear lighter than those on the left. They are the same colour. The effect results from the graded background. This possibly results from the electrophysiological properties of the Retinal Ganglion cells. What happens if we change the colours in the background or in the letters themselves? Here are some examples.

illusionblackongrey

What is interesting about this black text on grey background is that the illusion vanishes. All other colours will be lighter and perhaps the original effect relies on background colours being both lighter and darker than the letter colours.

illusionwhiteongrey

In the same vein, the effect also appears to be lost here.

illusionblueongrey

The blue on grey combination produces a contrast effect. In the word ‘contrast’ the first few letters appeared to me to be darker than the last few although I will leave it to the reader to see if they are persuaded. Perhaps the effect is stronger if the background and letter colours are similar.

illusionblueonblue

The effect seems more marked here than in the previous diagram. Perhaps then the contrast illusion depends on a contrasting background and letters of similar colour.

Appendix

Explaining the Neurobiology of Illusions – A Talk from Caltech

Do Cats See Illusions Too?

A Visual Illusion Experiment – Part 7

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 justinmarley17@yahoo.co.uk. 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.

4 thoughts on “The Effect of Colour on a Contrast Illusion: Continuing with a Visual Illusion Experiment – Part 8

  1. Minneapolis psychiatrist

    I, too, noticed darker letters when you introduced blue. Very interesting optical illusion here! I haven’t read your previous posts on illusions so I will have to check out all your previous experiments. Thanks for linking to them.

  2. Pingback: How to Import Blog Posts into Mendeley: A Look at Mendeley Part 3 | The Amazing World of Psychiatry: A Psychiatry Blog

  3. Pingback: Contrast Illusions and Geometry: Continuing with a Visual Illusion Experiment – Part 10 | The Amazing World of Psychiatry: A Psychiatry Blog

  4. Pingback: Intermezzo: A Visual Illusion Experiment – Part 11 | The Amazing World of Psychiatry: A Psychiatry Blog

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s