Inner speech signals, but isn’t a psychic telephone

New Scientist reports on a neck-band technology that allows the wearer’s silent thoughts to trigger messages over a phone line.

It sounds impressive, but the video that accompanies the story makes it look like the technology reads your inner thoughts and transmits them as sounds, when it fact it does something far more basic.

Whenever we think to ourselves, rather curiously, the vocal chords get activated very slightly – faintly mirroring what would happen if we were to say the words out loud.

This is known as subvocal speech and can be picked up by EMG sensors on the neck that pick up the tiny electrical signals generated by the weakly activated muscles.

While the technology doesn’t exist to turn these signals back into speech, it is possible to train the system to distinguish between a number of different general patterns which can trigger specific computer commands.

Lancet Neurology reported in 2004 that the same team had a basic system running that recognised six words (stop, go, left, right, alpha, omega) and 10 digits, to allow ‘silent’ control of a machine or a software application.

The team seem to have developed the technology and it can apparently now recognise many more commands, however, it doesn’t ‘translate’ thoughts into their corresponding words.

In the video, the wearer is triggering sound recordings of specific sentences, pre-arranged to provide answers to the rehearsed telephone ‘conversation’. Still impressive, but not a genuine conversation in the way we would normally think of it.

As an aside, for more than 20 years now, we’ve know that subvocal speech accompanies hallucinated voices in people who have been diagnosed with psychosis.

This means people who hear constant hallucinated voices will probably not be able to use the system effectively.

However, we now know that healthy individuals have much higher levels of hallucinations than previously thought, although most people are not bothered or distressed by them.

For example, in a 2004 study Louise Johns and colleagues found that 0.7% of the British population had experienced an auditory hallucination in the last year.

It’s interesting to speculate that a significant minority of the population might experience problems with this technology as their hallucinations accidentally trigger commands or send messages on their behalf!

Link to NewSci story ‘Nerve-tapping neckband allows ‘telepathic’ chat’.
Link to video of product presentation.

3 Comments

  1. Posted March 13, 2008 at 7:11 pm | Permalink

    Very interesting, especially the link to hallucinations. And good luck in Latin America!

  2. neuroshrink
    Posted March 14, 2008 at 2:34 am | Permalink

    I haven’t read the other stories, but I did click through the link about subvocal speech and auditory hallucinations. I don’t have easy access to the whole paper (it’s not online as far as I can tell), but the abstract seems to indicate that subvocal speech is NOT correlated with auditory hallucinations. That doesn’t mean that subvocal speech isn’t important or interesting, but I’m disappointed: I thought I would have an interesting factoid to show off on the ward tomorrow. Here’s some of the abstract (emphasis added):
    “Results essentially replicated studies that found increased vocal potentials in hallucinators, but also showed that these increased potentials were NONSIGNIFICANT when nonvocal measures are included in the statistical analysis. Subvocal speech and coincident increases in vocal EMG with reports of hallucinations, and with reports of pre-recorded statements, were NOT FOUND. ”

  3. Posted March 14, 2008 at 9:11 am | Permalink

    Hi Neuroshrink and thanks for your comment. Trust me to link to the study with the weakest findings for the phenomenon! The link below is to the abstract of a more recent paper and section 3.2 specifically reviews the well-replicated subvocal findings in this area.

    http://www.ncbi.nlm.nih.gov/pubmed/11378315

    Enjoy!
    Vaughan


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