In this article, the author shares an anecdote demonstrating one-trial learning which is commonplace in human behavior. The demonstration suggests that under some conditions, when people hear someone speak, their behavior changes, even in the absence of an apparent contingency of reinforcement, but only if they have in their repertoire verbal operants whose stimulus products are the same as those of the speaker. Effective listening is so commonly a necessary precursor of effective action that any invariant stimuli correlated with effective listening should acquire a conditioned reinforcing function. This conditioned reinforcing function would of course be sensitive to context. In the presence of one's garrulous aunt the value of effective listening would be discounted; when taking directions from one's boss it would be inflated. The author's anecdote offers no support for "zero-trial learning." Human behavior is exquisitely sensitive and complexly determined, but a consideration of contingencies of reinforcement, the author contends, is still the most powerful interpretive tool and putatively a sufficient one. (Contains 1 footnote.)