The present article reviews the effects of changing the background context on performance in associative learning tasks in humans and animals. The findings are complementary and consistent over animal conditioning (Pavlovian and instrumental learning) and human predictive learning and memory paradigms. In many cases, a context change after learning can have surprisingly little disruptive influence on performance. Extinction, or retroactive interference treatments more generally, are more context-specific than the initial learning. Contexts become important if the participant is exposed to any of several treatments that involve prediction error, which may serve to increase attention to the context. Contexts also become important if they are given predictive or informational value. Studies of instrumental (operant) learning are further consistent with the idea that the context might also influence affordances that support voluntary actions. Context switch effects are not universal, but mainly occur when certain attention and perception processes can come into play.The present article provides a brief review of the role of context that has emerged in recent studies of associative learning. "Associative learning" is a term that is broadly used to refer to a range of learning phenomena that are studied in humans and other animals. Throughout the past century and the beginning of the present one, classical and instrumental conditioning became essential tools for the study of how organisms learn about their environment, as well as to understand some of the neurobiological mechanisms that underlie it 1 . In classical (or Pavlovian) conditioning, animals learn about events that occur in their environment. For example, in Pavlovian fear conditioning, rats might learn that the presentation of an auditory cue (e.g., a tone) predicts the occurrence of an aversive stimulus, such as a mild foot shock. In instrumental (or operant) conditioning, the rat's own behavior produces the reinforcer. For example, rats might be trained to press a lever to obtain a food pellet reinforcer. As we will illustrate in this paper, similar procedures have recently been used in the human experimental psychology laboratory to study human predictive, diagnostic, and instrumental learning 2, 3, 4 . Associative learning can also be used as a tool to understand how memory works in both human and nonhuman animals. Traditional list learning has been complemented by learning about the correlation between cues or responses and outcomes, akin to nonhuman animal classical and instrumental conditioning 5 . Most of the research has uncovered striking similarities between basic learning processes in human and nonhuman animals (for instance, compare 6 with 7 ).One insight about associative learning is that it never takes place in a vacuum--it always takes place in the presence of background stimuli or contextual cues. A goal of many studies of human and nonhuman associative learning has therefore been to understand what role, ifCorrespondence concerning...