What you see affects what you hear (Videos)

Mar 04, 2009

Understanding what a friend is saying in the hubbub of a noisy party can present a challenge - unless you can see the friend's face.

New research from Baylor College of Medicine in Houston and the City College of New York shows that the visual information you absorb when you see can improve your understanding of the spoken words by as much as sixfold.

Your brain uses the visual information derived from the person's face and lip movements to help you interpret what you hear, and this benefit increases when the sound quality rises to moderately noisy, said Dr. Wei Ji Ma, assistant professor of neuroscience at BCM and the report's lead author, in a report that appears online today in the open access journal PLoS ONE.

This video is not supported by your browser at this time.
Example of congruent AV stimuli (boot) - 12dB noise.

"Most people with normal hearing lip-read very well, even though they don't think so," said Ma. "At certain noise levels, lip-reading can increase word recognition performance from 10 to 60 percent correct."

However, when the environment is very noisy or when the voice you are trying to understand is very faint, lip-reading is difficult.

This video is not supported by your browser at this time.
Examples of congruent AV* stimuli (cheap) - 12dB noise

"We find that a minimum sound level is needed for lip-reading to be most effective," said Ma.

This research is the first to study word recognition in a natural setting, where people report freely what they believe is being said. Previous experiments only used limited lists of words for people to choose from.

The lip-reading data help scientists understand how the brain integrates two different kinds of stimuli to come to a conclusion.

Ma and his colleagues constructed a mathematical model that allowed them to predict how successful a person will be at integrating the visual and auditory information.

People actually combine the two stimuli close to optimally, Ma said. What they perceive depends on the reliability of the stimuli.

"Suppose you are a detective," he said. "You have two witnesses to a crime. One is very precise and believable. The other one is not as believable. You take information from both and weigh the believability of each in your determination of what happened."

In a way, lip-reading involves the same kind of integration of information in the brain, he said.

In experiments, videos of individuals were shown in which a person said a word. If the person is presented normally, the visual information provides a great benefit when it is integrated with the auditory information, especially when there is moderate background noise. Surprisingly, if the person is just a "cartoon" that does not truly mouth the word, then the visual information is still helpful, though not as much.

In another study, the person mouths one word but the audio projects another, and often the brain integrates the two stimuli into a totally different perceived word.

"The mathematical model can predict how often the person will understand the word correctly in all these contexts," Ma said.

More information: Wei Ji Ma, Xiang Zhou, Lars A. Ross, John J. Foxe, Lucas C. Parra, " Lip-reading aids word recognition most in moderate noise: a Bayesian explanation using high-dimensional feature space," PLoS ONE, in press, to appear March 2009. dx.plos.org/10.1371/journal.pone.0004638

Source: Baylor College of Medicine

Explore further: 'Trigger' for stress processes discovered in the brain

add to favorites email to friend print save as pdf

Related Stories

Hackers force message on websites via US firm

1 hour ago

A U.S. firm that helps connect more than 700 companies with customers through social media says a Syrian group hacked the company's web address to upload a message to other websites.

Genomes of malaria-carrying mosquitoes sequenced

3 hours ago

Nora Besansky, O'Hara Professor of Biological Sciences at the University of Notre Dame and a member of the University's Eck Institute for Global Health, has led an international team of scientists in sequencing ...

Recommended for you

'Chatty' cells help build the brain

1 hour ago

The cerebral cortex, which controls higher processes such as perception, thought and cognition, is the most complex structure in the mammalian central nervous system. Although much is known about the intricate ...

'Trigger' for stress processes discovered in the brain

16 hours ago

At the Center for Brain Research at the MedUni Vienna an important factor for stress has been identified in collaboration with the Karolinska Institutet in Stockholm (Sweden). This is the protein secretagogin ...

New research supporting stroke rehabilitation

Nov 26, 2014

Using world-leading research methods, the team of Dr David Wright and Prof Paul Holmes, working with Dr Jacqueline Williams from the Victoria University in Melbourne, studied activity in an area of the brain ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.