Abstract—In both Pavlovian conditioning and human causal judgment, competition between cues is well known to occur when multiple cues are presented in compound and followed by an outcome. More questionable is the occurrence of competition between outcomes when a single cue is followed by multiple outcomes presented in compound. In the experiment reported here, we demonstrated blocking (a type of stimulus competition) between outcomes. When the cue predicted one outcome, its ability to predict a second outcome that was presented in compound with the first outcome was reduced. The procedure minimized the likelihood that the observed competition between outcomes arose from selective attention. The competition between outcomes that we observed is problematic for contemporary theories of learning. When a cue (i.e., an antecedent event) is followed by an outcome (i.e., a subsequent event), the association that is ordinarily formed may be assessed predictively (i.e., by presenting the cue and assessing whether participants predict the outcome) or diagnostically (i.e., by presenting the outcome and assessing whether participants diagnose the cue). Moreover, when two cues are presented together prior to an outcome, the cue with the higher predictive value ordinarily competes with the other cue for predicting the outcome. Examples of cue competition include overshadowing (Pavlov, 1927), blocking (Kamin, 1968), and the relative stimulus-validity effect (Wagner, Logan, Haberlandt, & Price, 1968; Wasserman, 1974). Cue competition occurs in both humans and animals (e.g., Balaz, Gutsin, Cacheiro, & Miller, 1982; Kamin, 1968; Matute, Arcediano, & Miller, 1996; Shanks, 1985; Wasserman, 1990) and is now an established phenomenon that is addressed by many models developed in areas as diverse as neural networks, animal conditioning, causal attribution, and categorization

In the analysis of stimulus competition in causal judgment, 4 variables have been frequently confounded with respect to the conditions necessary for stimuli to compete: causal status of the competing stimuli (causes vs. effects), temporal order of the competing stimuli (antecedent vs. subsequent) relative to the noncompeting stimulus, directionality of training (predictive vs. diagnostic), and directionality of testing (predictive vs. diagnostic). In a factorial study using an overshadowing preparation, the authors isolated the role of each of these variables and their interactions. The results indicate that competition may be obtained in all conditions. Although some of the results are compatible with various theories of learning, the observation of stimulus competition in all conditions calls for a less restrictive reformulation of current learning theories that allows similar processing of antecedent and subsequent events, as well as of causes and effects. Stimulus competition is defined as the phenomenon in which responding to a target stimulus (X), on the basis of its signaling some event, is weakened as a consequence of X’s being trained in the presence of another stimulus (A) that better signals the same

The concordance between performance and judgements of the causal effectiveness of an instrumental action suggests that such actions are mediated by causal knowledge. Although causal learning exhibits many associative phenomena—blocking, inhibitory or preventative learning, and super-learning—judgements of the causal status of a cue can be changed retrospectively as a result of learning episodes that do not directly involve the cue. In order to explain retrospective revaluation, a modi®ed associative theory is described in which the learning processes for retrieved cue representations are the opposite to those for presented cues, and this theory is evaluated by studies of the role of within-compound associations in retrospective revaluation and blocking. However, this modi®ed theory only applies when the within-compound association represents a contiguous rather than a causal cue relationship. Causal learning and representation is a fundamental form of cognition, if not the fundamental form. Without the capacity to learn about and represent the causal relationships between our actions and their consequences, the mind would be radically disconnected from the world. However detailed and rich our knowledge, however sophisticated and complex our inferences and planning, cognition would be impotent if our thoughts could not be

Within-compound associations in retrospective revaluation and in direct learning: A challenge for comparator theory

Reversal from blocking in humans as a result of posttraining extinction of the blocking stimulus FRANCISCO ARCEDIANO, MARTHA ESCOBAR, and HELENA MATUTE Universidad de Deusto, Bilbao, Spain In a blocking procedure, conditioned stimulus (CS) A is paired with the unconditioned stimulus (US) in Phase 1, and a compound of CSs A and X is then paired with the US in Phase 2. The usual result of such a treatment is that X elicits less conditioned responding than if the A–US pairings of Phase 1 had not occurred. Obtaining blocking with human participants has proven difficult, especially if a behavioral task is used or if the control group experiences reinforcement of a CS different from the blocking CS in Phase 1. In the present series, in which human participants and a behavioral measure of learning were used, we provide evidence of blocking, using the above described control condition. Most important, we demonstrate that extinction of the blocking CS (A) following blocking treatment reverses the blocking deficit (i.e., increases responding to X). These results are at odds with traditional associative theories of learning, but they support current associative theories that predict that posttraining manipulations of the competing stimulus can result in a reversal of stimulus competition phenomena.

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Recent computational theories of decision making in humans and animals have portrayed two systems locked in a battle for control of behavior. One system—variously termed “model-free” or “habitual”—favors actions that have previously led to reward, while a second called the “model-based ” or “goal-directed ” system favors actions that causally lead to reward according to the agent’s internal model of the environment. Some evidence suggests that control can be shifted between these systems using neural or behavioral manipulations, but other evidence suggests that the systems are more intertwined than a competitive account would imply. In four behavioral experiments, using a retrospective revaluation design and a cognitive load manipulation, we show that human decisions are more consistent with a cooperative architecture in which the model-free system controls behavior, while the model-based system trains the model-free system by replaying and simulating experience. Model-Based Revaluation 3