Conditioned suppression is a useful technique for assessing whether subjects have learned a CS ± US association, but it is dif ® cult to use in humans because of the need for an aversive US. The purpose of this research was to develop a non-aversive procedure that would produce suppression. Subjects learned to press the space bar of a computer as part of a video game, but they had to stop pressing whenever a visual US appeared, or they would lose points. In Experiment 1, we used an A+/B2 discrimination design: The US always followed Stimulus A and never followed Stimulus B. Although no information about the existence of CSs was given to the subjects, suppression ratio results showed a discrimination learning curveÐ that is, subjects learned to suppress responding in anticipation of the US when Stimulus A was present but not during the presentations of Stimulus B. Experiment 2 explored the potential of this preparation by using two different instruction sets and assessing post-experimental judgements of CS A and CS B in addition to suppression ratios. The results of these experiments suggest that conditioned suppression can be reliably and conveniently used in the human laboratory, providing a bridge between experiments on animal conditioning and experiments on human judgements of causality.

According to the two-stage model of voluntary action, the ability to perform voluntary action is acquired in two sequential steps. Firstly, associations are acquired between representations of movements and of the e#ects that frequently follow them. Secondly, the anticipation or perception of an acquired action effect primes the movement that has been learnt to produce this effect; the acquired action-e#ect associations thus mediate the selection of actions that are most appropriate to achieve an intended action goal. If action-effect learning has an associative basis, it should be influenced by factors that are known to a#ect instrumental learning, such as the temporal contiguity and the probabilistic contingency of movement and effect. In two experiments, the contiguity or the contingency between key presses and subsequent tones was manipulated in various ways. As expected, both factors affected the acquisition of action-effect relations as assessed by the potency of action effects to prime the corresponding action in a later behavioral test. In particular, evidence of action-effect associations was obtained only if the effect of the action was delayed for no more than 1 s, if the effect appeared more often in the presence than in the absence of the action, or if action and effect were entirely uncorrelated but the effect appeared very often. These findings support the assumption that the control of voluntary actions is based on action-effect representations that are acquired by associative learning mechanisms.

Two experiments are reported that examine the role of temporal contiguity on judgments of contingency in a human analogue of the Pavlovian task. The data show that the effect of the actual delay on contingency judgment depends on the observers expectation regarding the delay. For a fixed contingency between the cue and the outcome, ratings of the contingency are higher when the actual delay is congruent with the observers expectation than when it is incongruent. We argue that our data can be understood within the context of the temporal coding hypothesis. There is considerable evidence of similarities between the operations that modulate the strength of conditioning in nonhuman animals and those that modulate the rating of the contingency between events by humans (see Allan, 1993). One of these similarities is the effect of temporal contiguity. It is well established in the animal literature that temporal contiguity is an important variable in both instrumental and Pavlovian conditioning (see Allan, Balsam, Church, & Terrace, 2002; Allan & Church, 2002). For example, increasing the delay between a response and reinforcement in an instrumental task decreases the rate of responding. Similarly, increasing the delay between a conditioned stimulus and an unconditioned stimulus in a Pavlovian task retards the acquisition of the conditioned response. The studies that have examined the effect of temporal contiguity on ratings of contingency have used human analogues of the animal instrumental procedure (e.g., Buehner & May,

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

The associative sequence learning model proposes that the development of the mirror system depends on the same mechanisms of associative learning that mediate Pavlovian and instrumental conditioning. To test this model, two experiments used the reduction of automatic imitation through incompatible sensorimotor training to assess whether mirror system plasticity is sensitive to contingency (i.e. the extent to which activation of one representation predicts activation of another). In Experiment 1, residual automatic imitation was measured following incompatible training in which the action stimulus was a perfect predictor of the response (contingent) or not at all predictive of the response (non-contingent). A contingency effect was observed: there was less automatic imitation, indicative of more learning, in the contingent group. Experiment 2 replicated this contingency effect and showed that, as predicted by associative learning theory, it can be abolished by signaling trials in which the response occurs in the absence of an action stimulus. These findings support the view that mirror system development depends on associative learning, and indicate that this learning is not purely Hebbian. If this is correct, associative learning theory could be used to explain, predict and to intervene in mirror system development. 2

Many studies of contingency judgments have used a task in which, on each trial, the participant is free either to respond or not to respond, and an outcome may, or may not, be presented. Typically, the experimenter specifies a nominal value for the contingency between responding and outcome, but the actual values of a variety of variables experienced by a particular participant depend on that participant’s frequency of responding. The results of computer simulations of various strategies for implementing the contingency manipulation, and the results of an experiment, indicate that the same nominal contingency value will lead to considerable variability in the actual contingency experienced by participants. Moreover, nominal contingency manipulations are confounded with the probability that the subject experiences an outcome. While researchers might be aware of these issues, not enough attention has been paid to their potential impact. © 2006 Published by Elsevier B.V.