Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

How Do We Make Sense of What We See?

21.11.2007
Johns Hopkins researchers identify how brains
rationalize ambiguous visual data

M.C. Escher's ambiguous drawings transfix us: Are those black birds flying against a white sky or white birds soaring out of a black sky?


M.C. Escher

Lines in Escher's drawings can seem to be part of either of two different shapes. How does our brain decide which of those shapes to "see?" In a situation where the visual information provided is ambiguous — whether we are looking at Escher's art or looking at, say, a forest — how do our brains settle on just one interpretation?

In a study published this month in Nature Neuroscience, researchers at The Johns Hopkins University demonstrate that brains do so by way of a mechanism in a region of the visual cortex called V2.

That mechanism, the researchers say, identifies "figure" and "background" regions of an image, provides a structure for paying attention to only one of those two regions at a time and assigns shapes to the collections of foreground "figure" lines that we see.

Rudiger von der Heydt

"What we found is that V2 generates a foreground-background map for each image registered by the eyes," said Rudiger von der Heydt, a neuroscientist, professor in the university's Zanvyl Krieger Mind/Brain Institute and lead author on the paper. "Contours are assigned to the foreground regions, and V2 does this automatically within a tenth of a second."

The study was based on recordings of the activity of nerve cells in the V2 region in the brain of macaques, whose visual systems are much like that of humans. V2 is roughly the size of a microcassette and is located in the very back of the brain. Von der Heydt said the foreground- background "map" generated by V2 also provides the structure for conscious perception in humans.

"Because of their complexity, images of natural scenes generally have many possible interpretations, not just two, like in Escher's drawings," he said. "In most cases, they contain a variety of cues that could be used to identify fore- and background, but oftentimes, these cues contradict each other. The V2 mechanism combines these cues efficiently and provides us immediately with a rough sketch of the scene."

Von der Heydt called the mechanism "primitive" but generally reliable. It can also, he said, be overridden by decision of the conscious mind.

"Our experiments show that the brain can also command the V2 mechanism to interpret the image in another way," he said. "This explains why, in Escher's drawings, we can switch deliberately" to see either the white birds or the dark birds.

The mechanism revealed by this study is part of a system that enables us to search for objects in cluttered scenes, so we can attend to the object of our choice and even reach out and grasp it.

"We can do all of this without effort, thanks to a neural machine that generates visual object representations in the brain," von der Heydt said. "Better yet, we can access these representations in the way we need for each specific task. Unfortunately, how this machine' works is still a mystery to us. But discovering this mechanism that so efficiently links our attention to figure-ground organization is a step toward understanding this amazing machine."

Understanding how this brain function works is more than just interesting: It also could assist researchers in unraveling the causes of — and perhaps identifying treatment for — visual disorders such as dyslexia.

Other authors include Fangtu T. Qiu and Tadashi Sugihara, both of the Zanvyl Krieger Mind-Brain Institute. Funding for the research was provided by the National Institutes of Health.

Lisa DeNike | EurekAlert!
Further information:
http://www.jhu.edu
http://www.mb.jhu.edu/vonderheydt.asp
http://neuroscience.jhu.edu/RudigervonderHeydt.php

More articles from Studies and Analyses:

nachricht Statistical method developed at TU Dresden allows the detection of higher order dependencies
07.02.2020 | Technische Universität Dresden

nachricht Novel study underscores microbial individuality
13.12.2019 | Bigelow Laboratory for Ocean Sciences

All articles from Studies and Analyses >>>

The most recent press releases about innovation >>>

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

Im Focus: Harnessing the rain for hydrovoltaics

Drops of water falling on or sliding over surfaces may leave behind traces of electrical charge, causing the drops to charge themselves. Scientists at the Max Planck Institute for Polymer Research (MPI-P) in Mainz have now begun a detailed investigation into this phenomenon that accompanies us in every-day life. They developed a method to quantify the charge generation and additionally created a theoretical model to aid understanding. According to the scientists, the observed effect could be a source of generated power and an important building block for understanding frictional electricity.

Water drops sliding over non-conducting surfaces can be found everywhere in our lives: From the dripping of a coffee machine, to a rinse in the shower, to an...

Im Focus: A sensational discovery: Traces of rainforests in West Antarctica

90 million-year-old forest soil provides unexpected evidence for exceptionally warm climate near the South Pole in the Cretaceous

An international team of researchers led by geoscientists from the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI) have now...

Im Focus: Blocking the Iron Transport Could Stop Tuberculosis

The bacteria that cause tuberculosis need iron to survive. Researchers at the University of Zurich have now solved the first detailed structure of the transport protein responsible for the iron supply. When the iron transport into the bacteria is inhibited, the pathogen can no longer grow. This opens novel ways to develop targeted tuberculosis drugs.

One of the most devastating pathogens that lives inside human cells is Mycobacterium tuberculosis, the bacillus that causes tuberculosis. According to the...

Im Focus: Physicist from Hannover Develops New Photon Source for Tap-proof Communication

An international team with the participation of Prof. Dr. Michael Kues from the Cluster of Excellence PhoenixD at Leibniz University Hannover has developed a new method for generating quantum-entangled photons in a spectral range of light that was previously inaccessible. The discovery can make the encryption of satellite-based communications much more secure in the future.

A 15-member research team from the UK, Germany and Japan has developed a new method for generating and detecting quantum-entangled photons at a wavelength of...

Im Focus: Junior scientists at the University of Rostock invent a funnel for light

Together with their colleagues from the University of Würzburg, physicists from the group of Professor Alexander Szameit at the University of Rostock have devised a “funnel” for photons. Their discovery was recently published in the renowned journal Science and holds great promise for novel ultra-sensitive detectors as well as innovative applications in telecommunications and information processing.

The quantum-optical properties of light and its interaction with matter has fascinated the Rostock professor Alexander Szameit since College.

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

13th AKL – International Laser Technology Congress: May 4–6, 2022 in Aachen – Laser Technology Live already this year!

02.04.2020 | Event News

“4th Hybrid Materials and Structures 2020” takes place over the internet

26.03.2020 | Event News

Most significant international Learning Analytics conference will take place – fully online

23.03.2020 | Event News

 
Latest News

Capturing 3D microstructures in real time

03.04.2020 | Materials Sciences

First SARS-CoV-2 genomes in Austria openly available

03.04.2020 | Life Sciences

Do urban fish exhibit impaired sleep? Light pollution suppresses melatonin production in European perch

03.04.2020 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>