María J. F. Abad

Transfer of control between causal predictive judgments and instrumental responding.

Four experiments were conducted to explore outcome-specific transfer from causal predictive judgments to instrumental responding. A video game was designed in which participants had to defend Andalusia from navy and air force attacks. First, they learned the relationship between two instrumental responses (two keys on a standard keyboard) and two different outcomes (destruction of the ships or destruction of the planes). Then they learned to predict which of two different stimuli predicted which outcome. Finally, they had the opportunity of making either of the two instrumental responses in the presence of either stimulus. Transfer was shown as a preference for the response that shared an outcome with the current stimulus. The presentation of the stimulus during the test produced a decrease in the overall rate of response. Responding to a neutral stimulus in Experiments 2 and 3 suggested that this overall decrease in responding was due to a combination of the time needed to process the meaning of the stimulus and the activation of the representation of the outcome in the presence of the stimulus during the test. Transfer between predictive judgments and instrumental responding mirrors the outcome-specific Pavlovian instrumental transfer observed in conditioning studies with rats.

Giving Contexts Informative Value Makes Information Context-Specific

Contexts are sometimes informative about relationships that occur within them and sometimes not. The goal of this experiment was to determine the effect of that information value on the context-specificity of learning. Participants performed an instrumental task within a computer game in which they defended different Andalucía beaches (contexts) by destroying several attackers (planes or tanks) by clicking on them (responses) with the mouse. A colored sensor (discriminative stimulus) indicated to participants which attacker could be destroyed in a given trial - that is, which of the instrumental responses would be reinforced. Three groups of participants received training on a discrimination between two discriminative stimuli (X and Y) in Context A. The discrimination was reversed in Context B for Group I (informative). Group NI1 received the same X-Y discrimination in Context B. Group NI2 did not receive training with X and Y in Context B. Additionally, participants received training with cue Z in Context A, which consistently signaled the same outcome. A single test trial with Z revealed a lower response rate in Context B than in Context A in Group I, while no differences across contexts were found in Groups NI1 and NI2. Results suggest that when the context is informative about relationships within the experimental setting, even those relationships for which the context is not informative become context-dependent.

Partial reinforcement and context switch effects in human predictive learning

Human participants were trained in a trial-by-trial contingency judgements task in which they had to predict the probability of an outcome (diarrhoea) following different cues (food names) in different contexts (restaurants). Cue P was paired with the outcome on half of the trials (partial reinforcement), while cue C was paired with the outcome on all the trials (continuous reinforcement), both cues in Context A. Test was conducted in both Context A and a different but equally familiar context (B). Context change decreased judgements to C, but not to P (Experiment 1). This effect was found only in the cue trained in the context where a different cue was partially reinforced (Experiment 2). Context switch effects disappeared when different cues received partial reinforcement in both contexts of training (Experiment 3). The implications of these results for an explanation of context switch effects in terms of ambiguity in the meaning of the cues prompting attention to the context (e.g., Bouton, 1997) are discussed.