Neural Signatures of Prediction Errors in a Decision-Making Task Are Modulated by Action Execution Failures

Decisions must be implemented through actions, and actions are prone to error. As such, when an expected outcome is not obtained, an individual should not only be sensitive to whether the choice itself was suboptimal, but also whether the action required to indicate that choice was executed successfully. The intelligent assignment of credit to action execution versus action selection has clear ecological utility for the learner. To explore this scenario, we used a modified version of a classic reinforcement learning task in which feedback indicated if negative prediction errors were, or were not, associated with execution errors. Using fMRI, we asked if prediction error computations in the human striatum, a key substrate in reinforcement learning and decision making, are modulated when a failure in action execution results in the negative outcome. Participants were more tolerant of non-rewarded outcomes when these resulted from execution errors versus when execution was successful but the reward was withheld. Consistent with this behavior, a model-driven analysis of neural activity revealed an attenuation of the signal associated with negative reward prediction error in the striatum following execution failures. These results converge with other lines of evidence suggesting that prediction errors in the mesostriatal dopamine system integrate high-level information during the evaluation of instantaneous reward outcomes.

31 Spain

This chapter discusses the law of set-off in Spain. Under Spanish law, set-off represents a means of extinguishing an obligation between a debtor and a creditor. Set-off occurs mainly as a form of payment rather than a guarantee. The chapter first considers set-off between solvent parties, focusing on the requirements of statutory set-off, set-off in case of assignment of credit rights, and set-off as a mechanism for creating security interests. It then examines set-off against insolvent parties, with emphasis on the scope of the prohibition set out in Article 58 of the Insolvency Act regarding set-off against an insolvent debtor and whether there are exceptions to this prohibition. The chapter also analyses set-off in financial transactions subject to Royal Decree Law 5/2005, along with cross-border situations relating to set-off against insolvent parties and choice of law with respect to set-off between solvent parties.

Information Theory, Memory, Prediction, and Timing in Associative Learning

Two information-theoretic principles—maximum entropy, and minimum description length—dictate a computational model of associative learning that explains cue competition (assignment of credit) and response timing. The theory's primitives are two cue types—state cues and point cues—and two stochastic distributions. The preferred stochastic model gives the relative code lengths for an efficient encoding of the data already seen; it predicts the data not yet seen; and the associated hazard function roughly predicts the observed timing of anticipatory (conditioned) behavior. State cues use the exponential distribution to encode, predict and time; point cues use a form of the Gaussian distribution that allows for event failure. An implementation of the refined minimum-description-length approach to stochastic model selection (Rissanen 1999) determines which stochastic model best compresses the data, and hence which is the best predictive model for a given protocol. The model brings into sharp focus the need to focus neurobiological inquiry on the coding question in memory.

Psychology of the Scientist: LXXX. Attitudes regarding Authorship Issues in Psychological Publications

The purpose of this article is to explore empirically issues and attitudes surrounding the assignment of credit for authorship in psychological research. A survey consisting of research tasks, vignettes, and questions relating to collaborations between faculty and students was completed by 203 individuals (23.3% response rate) from a national, random sample of faculty and graduate students. Analysis indicated that tasks related to manuscript writing, developing research ideas, and research design were important criteria for assigning credit of authorship. Status, seniority, and data collection were rated as unimportant to the assignment of credit. The issues surrounding collaborations between faculty and students were also examined.

A Method for Illustrating the Continuity of Behavior during Schedules of Reinforcement

In this article, we present a method for illustrating the continuity of behavior during schedules of reinforcement. Students experienced either a fixed-interval 15-sec schedule in which the first contact after 15 sec of a cursor on a computer screen with a 0.7-cm diameter virtual (invisible) target resulted in reinforcement (a beep) or a fixed-ratio 5 schedule in which every 5th contact with the target produced the reinforcer. In addition to illustrating the continuity of behavior, this method provides a means of exposing students to concepts and methods such as the acquisition of operant behavior, the assignment-of-credit problem, the organization of behavior across time, and the analysis of single-subject data.