In order to achieve a coherent and accurate representation of the environment, the brain binds together the inputs--for example, vision and audition--arriving from different senses. This process often occurs seamlessly and without any apparent effort or attention. However, researchers have now found that this integration of sensory signals can be disrupted when attention is diverted to a secondary task, suggesting that the integration, or "binding," does not occur as automatically as previously supposed. The new work is reported in the May 10 issue of Current Biology by Salvador Soto-Faraco and colleagues of the University of Barcelona and Ruth Campbell of University College London.

One classical example of how vision and audition come together is speech perception. Although we tend to think of speech as a purely auditory process, it is surprisingly sensitive to visual influences. This is quite evident when we try to follow a conversation in a noisy place, as listeners tend to look at the talker's lip movements--especially as we grow older and our hearing declines. Classical experiments revealed that if a heard "ba" syllable is dubbed to a talker seen to be saying "ga," the observer often "hears" "da"--a sound that has the characteristics of both the heard and seen speech but is different from either. This illusion, first reported by Harry McGurk in 1976, is so powerful that observers usually do not realize what has happened until they look away from the talker--at which point the illusion breaks up and the true auditory event ("ba") is heard.

The currently accepted view on the McGurk illusion and similar multisensory-integration phenomena is that so-called binding processes in the brain occur pre-attentively; that is, they occur automatically and unavoidably as long as the perceiver has access to both input channels. In the new study, the researchers tested this "automaticity" hypothesis directly by making observers perform a difficult task (an atte
'"/>

Contact: Heidi Hardman
hhardman@cell.com
1-617-397-2879
Cell Press
9-May-2005

Page: 1 2
Related biology news :

1. New research seeks to enhance alternative fuel integration in public vehicle fleets
2. Evolution of morphological integration
3. Essential tones of music rooted in human speech
4. US hearing health, better telephone speech
5. Born with a love of speech
6. Improved speech without vocal cords
7. Genetic cause of speech defect discovered
8. New research puts a fresh spin on current thinking of speech evolution in humans
9. Grasping metaphors: UC San Diego research ties brain area to figures of speech
10. New insight into brain and speech promises help for learning disabilities
11. Self-esteem falters among Chinese teens