Topic summary
Parallel Distributed Processing
Extracted from the Wikipedia article Connectionism.
The second wave
The second wave begun in the early 1980s. Some key publications included (John Hopfield, 1982) which popularized Hopfield networks, the 1986 paper that popularized backpropagation, and the 1987 two-volume book about the Parallel Distributed Processing (PDP) by James L. McClelland, David E. Rumelhart et al., which has introduced a couple of improvements to the simple perceptron idea, such as intermediate processors (known as "hidden layers" now) alongside input and output units and using sigmoidactivation function instead of the old 'all-or-nothing' function.