Normally we think of objects as part of a hierarchy. A chair is furniture. A wolf is a carnivore. An ostrich is a bird.
Does HTM theory have anything to say about this?
Does generalization mean that two input SDRs that are different but similar have an identical representation in the brain somewhere?
In HTM, the spatial pooler will represent similar input-SDRs with a similar, but not identical, set of columns.
The temporal pooler maintains a representation over time, as different features are observed.
It does generalize in a way, because:
- If it has learned 2 similar objects, and it starts out observing features that are in common to the two objects, the active cells in the higher layer will represent a union of the features of the two objects. Then once a differentiating feature is observed, the representation gets more specific (and sparser). So it goes from general to specific.
- it learns an allocentric representation, which I think means it is invariant to orientation, which means that it generalized over orientation.
But is the temporal pooler invariant to size? Or if it were a visual representation, would it be invariant to the angle of light that strikes the object? If it were observing letters in different fonts, I would think it would not generalize.
A hierarchy of layers that left out some information coming from below might have more general concepts near the top. But what information would be left out?
I doubt there are answers at this point, but any ideas?