Amos Tversky (1937–1996) was an Israeli cognitive psychologist and Kahneman's closest collaborator. Together they produced the heuristics-and-biases program that reshaped psychology and economics: representativeness, availability, anchoring, framing, and prospect-theory.
Colleagues described Tversky as terrifyingly sharp — quick to spot logical flaws and fearless in debate. The partnership with Daniel Kahneman was unusually productive; Kahneman credited Tversky with mathematical rigor and intellectual courage. Tversky died before the Nobel; the prize was awarded to Kahneman alone, though both names appear on the foundational papers.