Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


There’s more than meets the eye in judging the size of an object


Neuroscientists from the University of Washington and the University of Minnesota have found that the first area in the cortex of the human brain that receives information from the eyes processes the perceived size, rather than the actual size, of an object.

"Our eyes only tell us part of what we need to be able to see. The other part is done by the brain, taking the input from the eyes and making guesses or inferences about what’s out there in the enviro You can’t always trust your eyes. nment. Usually these inferences are very accurate, but sometimes they lead us astray in the form of visual illusions," said Scott Murray, a UW assistant psychology professor and lead author of a study published in the current issue of Nature Neuroscience.

Murray and his Minnesota colleagues, Huseyin Boyaci and Daniel Kersten, used functional magnetic resonance imaging (fMRI) to see how the brain processes the size of objects when faced with an illusion such as the long-known moon illusion. For centuries it has been known that the moon, while rising, looks huge when it is near the horizon and smaller when high in the sky. It is in reality always the same size.

The researchers used a similar illusion, one that looked at the perceived difference in the size of an object at different distances. For their experiment they placed two identical spheres decorated with a checkerboard pattern in the front and rear of a receding brick hallway. In this kind of illusion, the more distant object appears to occupy a larger portion of the visual field.

Using fMRI, the researchers examined how the brains of five people with normal vision registered this difference in perceived size.

They found that the brain region known as the primary visual cortex, which is the first area in the cortex to receive input from the retina, showed a difference. Even though both spheres occupied exactly the same size on the retina, the rear sphere activated an approximately 20 percent larger area in the primary visual cortex than the front sphere. This difference closely matched a perceptual difference in size made by the subjects. Asked about the size of the two spheres, the people estimated the back sphere to be about 20 percent larger than the front one.

Murray said the simplicity of the results can belie its importance to anyone not involved in vision research.

"It almost seems like a first grader could have predicted the result. But virtually no vision or neuroscientist would have. The very dominant view is that the image of an object in the primary visual cortex is just a precise reflection of the image on the retina. I’m sure if one were to poll scientists, 99 percent of them would say the ’large’ moon and the ’small’ moon occupy the same amount of space in the primary visual cortex , assuming they haven’t read our paper!"

Murray said such illusions are more than simple curiosities because they can help identify how the visual system works.

"Our finding is important because it demonstrates that the process of making inferences about visual properties in our environment is occurring in the earliest stages of the visual system," he said. "Researchers have long believed that the visual system is organized hierarchically, with early visual areas such as the primary visual cortex simply registering the physical input from the eyes and ’higher’ visual areas attempting to put all the information together. This work challenges these theories of the organization of the visual system."

Joel Schwarz | EurekAlert!
Further information:

More articles from Health and Medicine:

nachricht New potential cancer treatment using microwaves to target deep tumors
12.10.2016 | University of Texas at Arlington

nachricht Breakthrough in Mapping Nicotine Addiction Could Help Researchers Improve Treatment
04.10.2016 | UT Southwestern Medical Center

All articles from Health and Medicine >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: New 3-D wiring technique brings scalable quantum computers closer to reality

Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.

"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...

Im Focus: Scientists develop a semiconductor nanocomposite material that moves in response to light

In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.

A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...

Im Focus: Diamonds aren't forever: Sandia, Harvard team create first quantum computer bridge

By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.

"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...

Im Focus: New Products - Highlights of COMPAMED 2016

COMPAMED has become the leading international marketplace for suppliers of medical manufacturing. The trade fair, which takes place every November and is co-located to MEDICA in Dusseldorf, has been steadily growing over the past years and shows that medical technology remains a rapidly growing market.

In 2016, the joint pavilion by the IVAM Microtechnology Network, the Product Market “High-tech for Medical Devices”, will be located in Hall 8a again and will...

Im Focus: Ultra-thin ferroelectric material for next-generation electronics

'Ferroelectric' materials can switch between different states of electrical polarization in response to an external electric field. This flexibility means they show promise for many applications, for example in electronic devices and computer memory. Current ferroelectric materials are highly valued for their thermal and chemical stability and rapid electro-mechanical responses, but creating a material that is scalable down to the tiny sizes needed for technologies like silicon-based semiconductors (Si-based CMOS) has proven challenging.

Now, Hiroshi Funakubo and co-workers at the Tokyo Institute of Technology, in collaboration with researchers across Japan, have conducted experiments to...

All Focus news of the innovation-report >>>



Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

Agricultural Trade Developments and Potentials in Central Asia and the South Caucasus

14.10.2016 | Event News

World Health Summit – Day Three: A Call to Action

12.10.2016 | Event News

Latest News

Innovative technique for shaping light could solve bandwidth crunch

20.10.2016 | Physics and Astronomy

Finding the lightest superdeformed triaxial atomic nucleus

20.10.2016 | Physics and Astronomy

NASA's MAVEN mission observes ups and downs of water escape from Mars

20.10.2016 | Physics and Astronomy

More VideoLinks >>>