  As AI continues to advance, human-AI teams are inevitable. However, progress
in AI is routinely measured in isolation, without a human in the loop. It is
crucial to benchmark progress in AI, not just in isolation, but also in terms
of how it translates to helping humans perform certain tasks, i.e., the
performance of human-AI teams.
  In this work, we design a cooperative game - GuessWhich - to measure human-AI
team performance in the specific context of the AI being a visual
conversational agent. GuessWhich involves live interaction between the human
and the AI. The AI, which we call ALICE, is provided an image which is unseen
by the human. Following a brief description of the image, the human questions
ALICE about this secret image to identify it from a fixed pool of images.
  We measure performance of the human-ALICE team by the number of guesses it
takes the human to correctly identify the secret image after a fixed number of
dialog rounds with ALICE. We compare performance of the human-ALICE teams for
two versions of ALICE. Our human studies suggest a counterintuitive trend -
that while AI literature shows that one version outperforms the other when
paired with an AI questioner bot, we find that this improvement in AI-AI
performance does not translate to improved human-AI performance. This suggests
a mismatch between benchmarking of AI in isolation and in the context of
human-AI teams.
