On the tip of your tongue: Researchers reveal our motor system is activated when we hear speech
22 December 2009
Researchers funded by BBSRC and the Medical Research Council have discovered that the motor system is activated automatically when we hear speech. These findings could, in the future, play a central role in helping to unravel various language difficulties seen in adults and children.
The study, ‘Activation of Articulatory Information in Speech Perception’, was conducted by researchers at Royal Holloway, University of London, the MRC Cognition and Brain Sciences Unit, and Ghent University and is featured in the Proceedings of the National Academy of Sciences of the United States of America this week, and suggests that motor systems are recruited whenever we hear speech, irrespective of whether we are trying to ignore the speech that we are hearing.
Professor Kathleen Rastle, from the Department of Psychology at Royal Holloway, University of London, explained that the study was carried out by fitting each participant with a custom-made acrylic palate that measured contact between the tongue and the roof of the mouth 100 times per second whilst they were speaking, which formed a detailed picture of the tongue’s position during speech. The participants were asked to read aloud printed targets such as ‘koob’ whilst also listening to spoken distractors such as ‘toob’.
“Our key question was whether there would be evidence that participants had constructed programs for the movements involved in speaking from the spoken distractor syllables. We hypothesized that if motor systems are recruited when we listen to speech, then the way that target syllables were produced would be influenced by the characteristics of the spoken distractors”, she said.
Results showed that the articulation of target syllables was distorted toward the articulatory requirements of the spoken distractors. For example, in the production of the ‘K’ sound in ‘koob’, participants’ tongues were slightly further forward when they were trying to ignore the spoken distractor ‘toob’ than otherwise.
Professor Rastle says the results suggest that participants had activated articulatory programs of the spoken distractors even though doing so caused them to produce distorted speech.
“These findings provide the first evidence that when we hear speech, we activate the movements involved in speaking in an automatic and involuntary manner. Research must now focus on precisely how the motor system impacts on speech perception and on why the motor system is recruited when we listen to speech,” she said.
The researchers say that this study helps to understand the relationship between hearing and producing speech and could help explain things such as why our accents can unintentionally change when we visit or relocate to a foreign country and start sounding like those around us when we make no attempt to alter our mode of speaking.
“This phenomenon is likely to occur precisely because of the exquisite relationship between perceptual and motor systems revealed in our research”, Professor Rastle says.
“Nonetheless, there are limits to this tight coupling as evidenced by the fact that most of us cannot faithfully reproduce the foreign accents that we are able to hear. Future research will help to reveal the reasons behind these abilities and limitations.”
Notes to editors
Interviews are available with Kathleen Rastle, For more information contact 01784 443552.
The work was funded by the Biotechnology and Biological Sciences Research Council (UK) and by the Medical Research Council (UK).
The following scientists collaborated on the research:
- Dr. Ivan Yuen, Department of Psychology, Royal Holloway, University of London
- Dr. Matthew H. Davis, MRC Cognition and Brain Sciences Unit, Cambridge
- Prof. Marc Brysbaert, Department of Experimental Psychology, Ghent University, Belgium
- Prof. Kathleen Rastle, Department of Psychology, Royal Holloway, University of London
About Royal Holloway, University of London
The Royal Holloway is one of the UK’s leading teaching and research university institutions, ranked in the top 20 for research in the 2008 Research Assessment Exercise. One of the larger colleges of the University of London, Royal Holloway has a strong profile across the sciences, social sciences, arts and humanities. Its 8,000 students work with internationally-renowned scholars in 18 academic departments. Over 20% of students are postgraduates and 22% come from 130 different countries. Renowned for its iconic Founder’s Building, Royal Holloway is situated on an extensive parkland campus in Egham, Surrey, only 40 minutes from central London.
The Biotechnology and Biological Sciences Research Council (BBSRC) is the UK funding agency for research in the life sciences. Sponsored by Government, BBSRC annually invests around £450M in a wide range of research that makes a significant contribution to the quality of life for UK citizens and supports a number of important industrial stakeholders including the agriculture, food, chemical, healthcare and pharmaceutical sectors. BBSRC carries out its mission by funding internationally competitive research, providing training in the biosciences, fostering opportunities for knowledge transfer and innovation and promoting interaction with the public and other stakeholders on issues of scientific interest in universities, centres and institutes.
The Babraham Institute, Institute for Animal Health, Institute of Food Research, John Innes Centre and Rothamsted Research are Institutes of BBSRC. The Institutes conduct long-term, mission-oriented research using specialist facilities. They have strong interactions with industry, Government departments and other end-users of their research.
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