Published 29 December, 2014; last updated 10 December, 2020
Futurist Bruce Klein ran an informal online survey in 2007, asking ‘When will AI surpass human-level intelligence?”. He got 888 responses, from ‘friends’ of unspecified nature.
The results are shown below, taken from Baum et al, p4. Roughly 50% of respondents gave answers before 2050.