I’ve been working on an idea for several months: that exerting effort, force, has an subjective feeling, a quale, which lays behind a person’s intuitive idea of physics and causality.
The rough idea is something like this. An infant is born with the qualia of force. This set of feelings correlates with the infants movements. For example, a force quale occurs when the infant’s motor cortex sends a train of action potentials that result in movement of the infant’s right arm. On some occasions, movement of the arm causes the arm to hit an object, perhaps a hanging crib toy, which makes the object move. This is the germ of the infant’s concept of both force and causality. Later the infant generalizes the notion of force and causality when external objects collide or interact (Hume’s pool balls). 
There are two central ideas:
- The infant has an inner feeling, or qualia of force that correlates with its self-generated physical movements.
- The qualia of force is the germ of the intuitive notion of physics and causality. The qualia of force, force, physics and causality are inherently linked.
If this notion is true, there are many downstream connections. For example, free will. How does the infant gain control of its force qualia, that is, how does the infant gain a sense control over voluntary movement?
Update March 24 2014: @mambo_bab_e made an interesting comment via twitter. “I understand it [qualia of force—jk], but it does not seem qualia was necessary for the story”. This is a difficult issue. The comment almost has to be true; no one, to my knowledge, has identified a function for qualia that can’t be covered by “stimulus” or “identifiable stimulus”. On the other hand, I think “qualia of force” is a much better prototype of qualia than the much more common “red”. The internal feeling during motor action is strong and distinctive; it has a real feel to it. “Red”?, eh. My guess is that the essence of all qualia is that they have one or several dimensions such as hedonic value, force/effort. Hedonic value may be divided into separate dimensions corresponding to motivational systems (hunger, lust, thirst). The rough idea is that qualia relate external stimuli to body state.*
A second consideration is “imagined force”. My guess is that all qualia can be induced by real stimuli or imagined stimuli. The permits two things: hypothetical behavior which leads to efficient behavior; and the ability to generalize the qualia to agents other than the self. Thus the infant can say “I feel a force when I push the ball; the large ball feels a force when it pushes the small ball”.
I doubt if this fully answers mambo_bab_e’s question. Supplying a convincing argument for the value of qualia would be an achievement. Perhaps these are stepping stones.
*I think this corresponds to Damassio’s sense of qualia; I’ll have to check.
Corona Radiata 
John, you might be interested in this paper (if you haven’t seen it already): http://www.sciencedirect.com/science/article/pii/S1364661304001007 – it addresses the same question in a quite different way.
shane, thanks.
Fascinating paper.
‘ve also been thinking about mental simulation. Didn’t know about this paper.
Mental simulation is roughly this:
Imagine someone in your family asks you to move the very large chair from one side of the room to the other. You go through a series of simulations, that include both “qualia of force” and kinematics of movement, before your conclude either you can’t do it alone, or a possible strategy for moving the chair.
I’ve been reading a bit about motor system activation independent of movement and triggering movement. The rough idea is movement simulation. Gordon Shepherd Jr. and others.
This is an interesting idea, which I suspect has something to do with motor reafference. I wonder whether the “qualia of force” could also be described as a “sense of effort”? Anyway I’m intrigued to see how you will develop the idea.
Regards, Bill
Hi Bill,
Yes, I think “qualia of force” is the same as “sense of effort”.
Important in developing the idea is that there is a “qualia of imagined force”. Once can imagine lifting a heavy box, and imagine the force. This is part of vicarious trial-and-error. A series of imagined efforts can be held in mind and one selected for execution. This is, roughly, when we feel we have free will. Holding the feeling of several possible alternatives in mind, and selecting the best, is itself a quale, and is, in this way of thinking, why we feel we have free will. Whether we have free will is a separate question.
Work is the energy associated with the action of a force on an object that result in it’s displacement.. “Spending energy” corresponds well to the notion of effort and to the notion of change in the location of an object. From F=ma, a cognitive representation of force integrated twice gives a metric of space. Could this be the basis of an efferent copy component of path integration?