In the history of artificial intelligence, an AI winter is a period of reduced funding and interest in artificial intelligence research. The field has experienced several hype cycles, followed by disappointment and criticism, followed by funding cuts, followed by renewed interest years or even decades later.
There were two major winters approximately 1974–1980 and 1987–2000, and several smaller episodes, including the following:
1966: failure of machine translation
1969: criticism of perceptrons (early, single-layer artificial neural networks)
1971–75: DARPA’s frustration with the Speech Understanding Research program at Carnegie Mellon University
1973: large decrease in AI research in the United Kingdom in response to the Lighthill report
1973–74: DARPA’s cutbacks to academic AI research in general
1987: collapse of the LISP machine market
1988: cancellation of new spending on AI by the Strategic Computing Initiative
1990s: many expert systems were abandoned
1990s: end of the Fifth Generation computer project’s original goals