The University of Sussex

Untimed and misrepresented: connectionism and the computer metaphor

Inman Harvey

The computer metaphor for the mind or brain has long outlived its usefulness, being based on Cartesian ideas. Connectionism has not broken free from this metaphor, and this has stunted the directions connectionist research has taken. The subordinate role of timing in computations has resulted in networks with real-value timelags on signals passing between nodes being ignored. The notion of representation in connectionism is generally confused; this can be clarified when at all times it is made explicit who or what Q and S are in the formula "P is used by Q to represent R to S". Frequently they may be layers or modules within a network, but the typical confusion is symptomatic of the computer metaphor which in practice favours feedforward and militates against arbitrarily connected networks. Rejecting this metaphor, an alternative paradigm is suggested of a brain as a complex dynamical system; investigating the dynamics of arbitrarily connected networks with real-valued timelags, specified so as to produce appropriate behaviour when they act as a nervous system for an organism or machine in continuous longterm interaction with its environment. The practical differences a change of metaphor makes are pointed out, and possible techniques for pursuing this line are indicated.

Download compressed postscript file