Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Seeing is believing, even when what we see is ambiguous or misleading

14.06.2004


New research has found that the brain continues to accept ambiguous visual information about an object in motion even when it conflicts with more reliable information that we can touch. The studies, which appear in the June 7 issue of the journal Psychological Science and the forthcoming June issue of the journal Cognitive, Affective, & Behavioral Neuroscience, provide new insights into the way the brain blends and balances information from different senses.


Tom James
Credit: Daniel Dubois / Vanderbilt University



The research, conducted by Vanderbilt psychologists Randolph Blake, Centennial Professor of Psychology, and Thomas W. James and Kenith V. Sobel, research associates, found that the region of the brain that specializes in processing visual movement-the middle temporal visual center, or MT-also responds to motion that we feel. But they were surprised to discover that when individuals were presented with an ambiguous visual image and were able to touch that object, their brains did not fuse the visual and touch inputs into a single, accurate representation. Instead, the researchers found that the brain keeps the two inputs separate and accepts a degree of "cognitive dissonance" when the two conflict.

"This suggests that there is naturally a higher level of inconsistency between seeing and feeling something moving than there is between seeing and feeling something’s shape," says James.


To explore the relationship between vision and touch, the team developed a procedure that relies on a well-known visual illusion called the kinetic depth effect. The kinetic depth effect begins with a group of dots arranged in a circular pattern on a computer screen. The dots are programmed so that half move left to right and half move right to left. The dots’ movements are choreographed so that they move as if they are fixed to the surface of a transparent globe. This tricks the brain into seeing them as forming a rotating, three-dimensional sphere. The viewer cannot tell from the dots in which direction the sphere is turning. So the brain splits the difference-the sphere appears to rotate from right-to-left 50 percent of the time and from left-to-right 50 percent of the time.

The researchers set up a rotating Styrofoam ball that the subjects could touch with both hands and projected the moving dot illusion into their eyes in such a way that it appeared to be the same in every way as the physical ball.

"Our thought was that if a person touched something turning in a specific direction, then the perceptual system should fuse the tactile and visual information, resulting in people ’seeing’ a sphere rotating in a direction that was consistent with the more reliable source of sensory information," says James.

They found instead that the tactile and visual information did not fuse. The tactile information did, however, change the subjects’ perception of which direction the sphere was rotating. The amount of time that the subjects reported the visual sphere rotating in the same direction as the physical sphere jumped from 50 percent to 65 percent. Yet it still appeared to rotate in the opposite direction 35 percent of the time, in direct contrast to what they were feeling with their hands.

The researchers went a step further and monitored brain activity in the part of the brain most likely to be involved, the Middle Temporal visual center, using functional magnetic resonance imaging. This technique detects activity levels in different parts of the brain by measuring blood flow. They recorded a reliable increase in activity in MT when the globe was rotating compared to when it was stationary for both vision and touch. But the activity stimulated by the visual stimulus was four times greater than that generated by touch.

A central question remained unanswered: Why didn’t the visual and tactile information fuse? The researchers speculated that the fact that subjects could not see their fingers touching the rotating sphere might have been enough to keep the fusion from taking place.

So they came up with another approach, which is described in the Cognitive, Affective, & Behavioral Neuroscience article. They attached a wire-frame sphere to a motor to enable it to slowly rotate. When viewed with one eye closed, it created the same illusion as the moving dots. In this case, however, subjects were able to reach out and directly touch the sphere as they were looking at it to determine in which direction it was rotating.

The researchers were surprised to find that this procedure produced almost precisely the same results as their first effort. Without touching the sphere, subjects reported that it appeared to rotate in each direction approximately 50 percent of the time. When the subjects were touching the sphere, it appeared to them to rotate in the direction consistent with what they were feeling 60 to 70 percent of the time, while appearing to rotate in the opposite direction 30 to 40 percent of the time.

"It is surprising that an unreliable visual stimulus should be that resistant to tactile input," says James. "This points out that, in terms of visual motion processing, the mechanism that produces alterations in the perceptual state must be very powerful because it is not over-ridden even by highly reliable tactile input."

David F. Salisbury | Vanderbilt University
Further information:
http://www.vanderbilt.edu/news/releases?id=12560

More articles from Social Sciences:

nachricht Geographers provide new insight into commuter megaregions of the US
01.12.2016 | Dartmouth College

nachricht Sustainable Development Goals lead to lower population growth
30.11.2016 | International Institute for Applied Systems Analysis (IIASA)

All articles from Social Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Shape matters when light meets atom

Mapping the interaction of a single atom with a single photon may inform design of quantum devices

Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...

Im Focus: Novel silicon etching technique crafts 3-D gradient refractive index micro-optics

A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.

Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...

Im Focus: Quantum Particles Form Droplets

In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.

“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...

Im Focus: MADMAX: Max Planck Institute for Physics takes up axion research

The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.

The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...

Im Focus: Molecules change shape when wet

Broadband rotational spectroscopy unravels structural reshaping of isolated molecules in the gas phase to accommodate water

In two recent publications in the Journal of Chemical Physics and in the Journal of Physical Chemistry Letters, researchers around Melanie Schnell from the Max...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ICTM Conference 2017: Production technology for turbomachine manufacturing of the future

16.11.2016 | Event News

Innovation Day Laser Technology – Laser Additive Manufacturing

01.11.2016 | Event News

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

14.10.2016 | Event News

 
Latest News

High-precision magnetic field sensing

05.12.2016 | Power and Electrical Engineering

Construction of practical quantum computers radically simplified

05.12.2016 | Information Technology

NASA's AIM observes early noctilucent ice clouds over Antarctica

05.12.2016 | Earth Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>