Connectionist symbol processing: any progress?

[Eytan Ruppin]

 Jerry Feldman writes:

>  - PDP (Parallel Distributed Processing) is a contradiction in terms. 
> To the extent that representing a concept involves all of 
> the units in a system, only one concept can be active at 
> a time. Dave Rumelhart says this is stated somewhere in 
> the original PDP books, but I forget where. The same 
> basic point accounts for the demise of the physicists' 
> attempts to model human memory as a spin glass. 

  There is really no ``contradiction in terms'' here. Indeed, associative
memory networks (or attractor neural networks) can activate only one
stored concept at a time. However, such networks should not be viewed as
representing the whole brain but should be (and indeed
are) viewed as representing modular cortical structures such as columns. 
Given this interpretation, the problem is resolved; If these networks are 
sufficiently loosely coupled then many patterns can be
activated together, resulting in complex and rich dynamics.

 We should be careful before discarding our models on false grounds. We have
too few viable models that can serve as paradigms of information processing.

  Best wishes,

  Eytan Ruppin.