What is a quale? Here are a few examples:
When I stretch out my arms I have the sweep of those arms and a space that appears between them. I use the word "space" for a whole set of concurrent and simultaneous variations in my experience that is present between my hands and have come to use the term even when there is a continuum, such as a continuum of blackness in the dark. The space between my hands is a quale.
The black of a continuum of blackness is a quale.
The pain in an arm is a quale.
These examples seem quite heterogeneous but are there some basic qualia from which the others are constructed? Are there qualities in common between qualia?
Space or extent appears to be a basic quale, without extent there are no other qualia. As an example, if there were no space containing my head there would be no inner speech occurring between my ears and slightly above my larynx.
Dimensional time appears to be a another basic quale, a quale that exists for no time at all is non-existent for me. Notice that a quale with temporal extension does not occur without spatial extension and vice versa. This means that it is not space by itself or time by itself but spacetime that appears to be a basic quale.
The existence of time means that not only do we have spatial extension and temporal extension, we also have change in spatial extension. Change is hugely important, for instance, when I wave an arm outwards there is a "feeling" that is the movement. Feelings and active extension seem to be closely linked. For instance "She gasped in surprise", "He had a throbbing headache", "She sighed" etc. are all examples of motions and changes as emotions and feelings.
The last aspect of qualia that is heterogeneous is the way that a given area and time extension can be black, white, coloured, rough, loud, pungent, painful etc. this aspect of qualia might be called a "quality of substance". This quality appears to be independent of space and time. I say "appears" because there is a lower limit to the definition of spacetime. A space interval of a millionth of the angular displacement of the visual field or a time interval of a millionth of a clock tick may as well be zero in my experience. Either there is a true variety of qualities of substance or there is some underlying substance that alternates in space and time at very short intervals.
The separation of objects from the centre of vision or hearing is a quale that deserves special attention. This separation is as much a separation in time as a separation in space, and it is this confusion between time and space that leads to the mistaken impression that there must be some sort of flow into the centre of our vision or "mind's eye". There is no flow, just a projective geometry that allows qualia to be no distance from each other in certain directions in spacetime as well as distributed in space and time (See Time and Conscious Experience).