Re: Motor Imagery

From: Harnad, Stevan (
Date: Mon Oct 30 1995 - 20:18:48 GMT

> From: "Lucas, Melody" <>
> Date: Mon, 30 Oct 1995 18:43:57 GMT
> I wonder how the loss of visual imagery affects memory of visual
> events. Is imagery involved in rehearsal or is this a completely
> different part of the brain? What makes face recognition so special?

Jeannerod would think visual imagery was involved in visual rehearsal,
since he thinks motor imagery is involved in -- or even the same as --
motor rehearsal. The idea is more intuitive with movement, because
movement is in any case something you Do, whereas seeing just happens.
So rehearsing movement can be seen as an inner doing of the same thing.
Rehearsing seeing is not so obvious.

Face recognition is a special case. There is a motor theory of facial
expression recognition: You recognise a smile or a frown by inwardly
DOING it, and knowing what mood that is.

Harder to apply to recognising facial IDENTITY...

> Excellent! Cardio-vascular exercise whilst watching TV (and they call
> our generation couch potatoes!) On a serious note, this really does
> support the 'common substrate' idea.

Hard to believe, but possibly even true. We'll discuss this in class.
Meanwhile, try it!

> j> The object attributes are represented therein as affordances, that is,
> j> to the extent that they afford specific motor patterns, not as cues for
> j> a given perceptual category
> This supports previous studies concerning pragmatism and one can
> logically allow evolutionary 'law' to explain the occurrence of such a
> phenomenon.

Not sure what you mean here. This fits philosophical pragmaticism only
in a very nonspecific way. The evolution of the ability to detect and
act on affordances of course makes sense, as any functional adaptation
makes sense.

> j> The higher level is more difficult to describe in neurophysiological
> j> terms. The functional operations underlying motor planning, preparation
> j> and imagery must involve large neuronal ensembles, which are likely to
> j> be widely distributed. In addition, high-order representation neurons
> j> should encode complex goals, not only affordances.
> I'm not too sure about this one. This idea of a hierarchical model... I
> don't like models because they're not absolute! The problem is probably
> more likely to be that I'm tired and it has taken me hours to finish
> this. I'd like to understand it, though- perhaps tomorrow!

J is getting a bit fuzzy here; besides, he doesn't really have a model,
just some data. But models can be very informative when they work and
they can account for a lot of data. We'll discuss this in class too.

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