Founding the Field

Frank Rosenblatt

Psychologist who built the perceptron in 1958, the first neural network that learned its own weights from data rather than having them set by hand.

Frank Rosenblatt (1928–1971) took the McCulloch-Pitts neuron — a fixed logic gate with hand-set weights — and gave it a learning rule. His perceptron, built in 1958 as both an algorithm and a physical machine (the Mark I Perceptron, wired to a 20×20 grid of photocells), adjusted its own weights based on whether it classified an example correctly. Get it wrong, nudge the weights toward the right answer; repeat over the training set until it converges. That update rule is a direct, if simpler, ancestor of gradient descent and backpropagation.

Rosenblatt was also an aggressive promoter of his own work, and press coverage at the time suggested perceptrons would soon see, speak, and think — expectations the single-layer perceptron could never meet, since it can only separate data that's linearly separable. When Marvin Minsky and Seymour Papert's Perceptrons demonstrated this limitation rigorously in 1969, the gap between the hype and the math became impossible to ignore, and funding for neural network research collapsed for most of a decade.

Rosenblatt died in a boating accident in 1971, before the field revisited his ideas with the multi-layer networks and backpropagation that fixed exactly the limitation his critics had identified.

See also: Marvin Minsky, Warren McCulloch

Learn more: Neural Networks & Backprop · Wikipedia: Frank Rosenblatt

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