The connectionist model evolved out of Parallel Distributed Processing framework that formulates a metatheory from which specific models can be generated for specific applications. PDP approach (Rumelhart, J. L., McClelland, J. L., and PDP Research Group (1986)[1]) is a distributed parallel processing of many inter-related operations, somewhat similar to what's happening in the human nervous system. The individual entities are defined as units and the units are connected to form a network.