A friend pointed out that gesture in music is a large field of study and I've been surveying it a little.
One emphasis of study is on artificial reproductions of gesture, as well as technology that captures a gesture and interprets it. IRCAM has a large website on the subject of gesture and technology. The attempt to reproduce human gestures helps us to understand them. Breaking them down into smaller components, as we do in Awareness through Movement lessons, we can appreciate the complexity of a gesture.
Another emphasis is the meaning of musical gestures. Here's a quote from an article by Fernando Iazetta:
"Gestures increase function by virtue of their expressiveness. That is, a gesture may control multiple parameters at the same time, thus allowing a user to manipulate data in a manner not possible by modifying each parameter individually. For example, a conductor simultaneously controls both tempo and volume of the music gesture. The rhythm of the gesture controls tempo and the size of the gesture controls volume. This allows an efficient communication not possible by adjusting the tempo and volume independently."
Technologists break gestures apart to study them, but expressiveness puts them back together. How could a conductor adjust the tempo and volume independently? In making a musical gesture, such as conducting the shape of a phrase, we don't consciously manage all the parameters. We don't say to ourselves, "now I'm going to move my arm a distance of eighteen inches in an upward diagonal movement, inhaling as I do so," or "I am going to indicate a tempo increase of 12% while simultaneously indicating a gradual increase in volume." We think of an expressive intent--an increase in excitement, for instance.
We sense the shape of the phrase and the movements organize themselves to carry out our intention. If we aren't certain of our intention, the gesture will seem more self-conscious. It's fairly apparent when a conductor spends time practicing in front of a mirror, or when any musician is more taken with the look of a gesture than with the underlying musical meaning.
And in playing an instrument, an image of an expressive gesture will help all the technical details of execution fall into place, usually making the technical execution feel much easier. Conscious micromanagement of all the details of fingering, rhythm, and articulation can get in the way of a fluid performance. Conscious control of intention is far more effective than conscious control of technical execution.