Optical illusions show vision in a new light

Mar 11, 2011

Optical illusions have fascinated humans throughout history. Greek builders used an optical illusion to ensure that that their columns appeared straight (they built them with a bulge) and we are all intrigued by the mental flip involved in the case of the young girl/old woman faces. New research published in BioMed Central's open access journal BMC Neuroscience demonstrates a more serious use of these illusions in understanding how the brain assesses relative size.

Researchers from University College London looked at two well known illusions: the Ebbinghaus illusion, where an object surrounded by small circles appears bigger than the same object surrounded by bigger circles, and the Ponzo illusion, where an object within converging lines (like train tracks or a corridor) is perceived to be larger than a same sized object nearer to the observer.

Their results show that the Ponzo illusion holds true regardless of which eye is used or whether the environmental clues are presented to a different eye than the objects. This suggests that our clues about relative size at a distance are determined after the two-dimensional images seen by the eyes have been processed into a single, three-dimensional, image. In contrast the Ebbinghaus does not work as well if the central object is presented to a different eye than the surrounding circles and shows that determination of an object's size relative to others in the same plane occurs before three-dimension processing.

Chen Song said, "Although our perception of size is distorted by environmental clues, this study shows that the extent of distortion and the brain mechanisms involved are dependent on the type of environmental contexts."

So while celebrity illusionists retain their ability to fool us, scientists can use these visual tricks to further our understanding of how we relate to the world around us – and have some fun at the same time!

Explore further: Early cerebellum injury hinders neural development, possible root of autism

More information: Interocular induction of illusory size perception, Chen Song, D. Samuel Schwarzkopf and Geraint Rees, BMC Neuroscience (in press)

add to favorites email to friend print save as pdf

Related Stories

Summer Moon Illusion

Jun 28, 2007

Sometimes you can't believe your eyes. This weekend is one of those times.

Hollow mask illusion fails to fool schizophrenia patients

Apr 06, 2009

Patients with schizophrenia are able to correctly see through an illusion known as the 'hollow mask' illusion, probably because their brain disconnects 'what the eyes see' from what 'the brain thinks it is seeing', according ...

Best Visual Illusion of the Year: How a Curveball Works

May 13, 2009

(PhysOrg.com) -- Visual illusions sometimes seem to have a magical element to them, but they're actually just the brain's way of interpreting reality. In an effort to promote public knowledge of cognitive ...

Recommended for you

Surprising new role for calcium in sensing pain

10 hours ago

When you accidentally touch a hot oven, you rapidly pull your hand away. Although scientists know the basic neural circuits involved in sensing and responding to such painful stimuli, they are still sorting ...

Neurons in human skin perform advanced calculations

Sep 01, 2014

Neurons in human skin perform advanced calculations, previously believed that only the brain could perform. This is according to a study from UmeƄ University in Sweden published in the journal Nature Ne ...

Memory in silent neurons

Aug 31, 2014

When we learn, we associate a sensory experience either with other stimuli or with a certain type of behavior. The neurons in the cerebral cortex that transmit the information modify the synaptic connections ...

User comments : 0