Wednesday, July 05, 2006

Inner Speech and Motor Imagery

More on "inner speech". (For earlier posts on inner speech see here and here and here and here.)

Say something silently to yourself. "Peter Piper picked a peck of pickled peppers." If you're like most, you'll have, in some sense, imagined the words auditorially. You'll have heard the words in an "inner voice" of some sort. At least, this is how it seems to me! Here's one way of expressing that fact, if it is a fact: Inner speech involves auditory imagery.

Now, some of the philosophers and psychologists who discuss the phenomenon of inner speech simply call inner speech auditory imagery, as if the auditory experience exhausts the phenomenology of it.

Maybe it does. Or maybe there's something else -- motor imagery perhaps? Just as one can (I think one can) motorically (as opposed to visually) imagine swinging one's leg or raising one's arms, or preparing to leap from a high place (I spent the last two nights in a 35 story hotel, so that particular vertiginous experience is vivid in my memory), so also can one motorically imagine speaking.

Now if I try, deliberately, to involve motor imagery in my inner speech, it seems that I can do so. But does inner speech normally involve such imagery? Hm! Why does this seem a hard question to answer?

Let's say it does. Here, then, is a further question: Is the motor aspect really only motor imagery? Some behaviorists speculated that what we call inner speech really involves subtle activation of the vocal apparatus -- actual sensed movement, not just private imagery. (I have the impression there's some work on this, but all I can seem to find right now are a few studies suggesting that the vocal apparatus is active during auditory hallucination in schizophrenia, and studies suggesting that brain areas associated with the motor aspects of speaking may be active during inner speech.)

Further: Is there a feeling of control or willing in inner speech? A number of people I've asked, including on this blog, seem ready to acknowledge an experiential difference between inner speech (experienced as actively created) and inner hearing (experienced as passively received).

So I'm puzzled about the phenomenology of inner speech. I don't want to overpopulate our inner lives with excessive complexity. Perhaps inner speech is pretty thinly experienced, and the richness we might be tempted to attribute to it -- feelings of motor imagery, feelings of control -- exists only when set our attention to such matters. (See my discussion of the refrigerator light error.) On the other hand, if such experiences generally belong to inner speech, that seems a fairly fundamental and basic thing to leave out in a phenomenological survey.

The cool thing here -- to my taste -- is that it seems like such matters should be obvious to a moment's reflection and introspection. And yet they're not, or not to me.


gualtiero piccinini said...

For what it's worth, my own introspection says that my inner speech is both auditory and motor.

Genius said...

One think that interests me is this exeriment
1) start saying somthing to yourself with your inner voice.
2) while still doing that try to say somthing else

I find I get a loud "outer inner voice" and a quiet "inner inner voice" both of which being different from inner hearing
Also inner inner hearing tends to be at a higher level ie you could use it to talk about the first type but it would be hard to do it the other way around - if not impossible.

Another interesting thing is I seem to be worse at it in my "old age"...

Genius said...

I mean saying somthing else in your head

Eric Schwitzgebel said...

Thanks for the two cents, Gualtiero. I'll add them to my informal poll.

I tried your experiment, Genius. I found the two speech streams to interfere with each other quite a bit, but I could kind of get it going if I rehearsed them separately beforehand. One was the lyrics of a song I knew well, which could kind of go on autopilot, and the other was a simple statement, long enough that I couldn't seem to squeeze it in the pauses between the lyrics.

I can't say I pulled it off without a hitch, but it seemed to me I did it (though I'm not entirely sure).

One interesting thing about this experiment is that if you really get two streams simultaneously, that seems to rule out a crucial role for actual movements in the vocal apparatus (which would be contradictory) -- and other similar "one stream" mechanisms.

Genius said...

I think with a bit of practice you would be able to get both going and you would be able to say something reasonably intelligent and dynamic - but maybe only with the quieter voice (while the other goes on auto pilot).
Although the fact some people can have "voices in their head" (e.g. "insane" people) might mean you can do both.

(You can probably tell I’m a pretty introspective person to have bothered to do this in my youth!).

Dave the Philosopher said...

Neuroscience has some light to throw on this issue, although it does not exhaust the issue, nor do we usually find the same emphasis in neuroscience as in philosophy. Though speech is distributed throughout the brain, there are two main speech networks: the receptive and the expressive. When the expressive network is damaged, one still understands language but has difficulty speaking and writing, whereas when the receptive network is damaged, not only does one not understand language, but when the person speaks, they speak a lot of incoherent nonsense--although they use grammatically correct form when doing so. It would seem from this that it is the receptive area that is more important in 'being a language user' and thinking in words. Therefore, I would submit that, from this kind of evidence, it is the sensory-perceptual area that is primary in inner speech. However, it must be stated that in normal brains the receptive and expressive areas of the brain are robustly interconnected, and in an individual it is likely that both sets of processes are invoked.

Just a thought. Sometimes when I hear inner speech, it is not as though I am speaking inside of my head, but like someone else is speaking, like I am hearing my thoughts rather than saying them to myself.