Decision theory,reinforcement learning,and the brain

Decision making is a core competence for animals and humans acting and surviving in environments they only partially comprehend, gaining rewards and punishments for their troubles. Decision-theoretic concepts permeate experiments and computational models in ethology, psychology, and neuroscience. Here, we review a well-known, coherent Bayesian approach to decision making, showing how it unifies issues in Markovian decision problems, signal detection psychophysics, sequential sampling, and optimal exploration and discuss paradigmatic psychological and neural examples of each problem. We discuss computational issues concerning what subjects know about their task and how ambitious they are in seeking optimal solutions; we address algorithmic topics concerning model-based and model-free methods for making choices; and we highlight key aspects of the neural implementation of decision making.     

Trait-level emotion regulation and emotional awareness predictors of empathic accuracy

Empathic accuracy (or how accurately a person perceives another’s emotions) has important implications for how individuals navigate their social world. We examined the role of two emotion-related traits (emotion regulation and emotional awareness) in predicting empathic accuracy and how these relationships may vary across racial groups. Undergraduate participants (N?=?98) watched videos of European-American, Asian-American, and African-American targets playing a frustrating game and made continuous ratings of the target’s emotion. To assess empathic accuracy, these ratings were compared to targets’ self-reported emotion. We found mixed support for our initial hypotheses, such that individual differences in reappraisal and attention to emotions predicted accuracy under certain conditions. Exploratory analyses suggested suppression and emotional clarity have an interactive effect in predicting accuracy. This study provides evidence for the importance of individual differences in attention to and regulation of one’s own emotions for interpersonal sensitivity, as well as the importance of context for these emotion-related traits.

     

Controlled comparison of aversive therapy and covert sensitization in compulsive homosexuality

Ethical objections to the use of behaviour therapy in homosexuality are discussed. It is pointed out that these objections were often based on a limited view of the aims of the therapy. The need for evaluating such therapy, as it is currently used, is elaborated.Twenty subjects requesting behaviour therapy to reduce compulsive homosexual urges were randomly allocated, half to receive aversive therapy using electric shocks and half to receive covert sensitization. Both groups were studied for one year. There was no consistent trend for one therapy to be more effective than the other in reducing the strength of compulsive homosexual urges, and the response to both was similar to that reported in previous studies. It was considered that aversive therapies in homosexuality do not act by establishing a conditioned aversion, nor by altering the subjects' sexual orientation. They reduce aversive arousal produced by behaviour completion mechanisms when subjects attempt to refrain from homosexual behaviour in response to stimuli which have repeatedly provoked such behaviour in the past.     

The pursuit of Leonardo's constraint

Leonardo da Vinci (1452-1519) identified two stimulus situations that cannot be painted faithfully on a canvas: (a) when two objects are located in the same direction with respect to the painter's head, and (b) when parts of a surface are visible to one eye, but occluded from the other eye. He analysed these situations in terms of rays being emitted from the two eyes and, aside from the origin of the rays, the projective geometry he used was correct. His analyses showed that what can be seen from two vantage points cannot be represented on a canvas, because a 'correct' painting must be created from a single 'station point'. He was struck by the consequence of this fact that the depth seen on a canvas cannot match that of viewing the scene with two eyes. Subsequent visual scientists focused on Leonardo's observation about the lack of vivid depth in a picture. We argue that a complete understanding of what we see in the two stimulus situations requires consideration of visual direction in addition to visual depth. More specifically, we argue that the visual directions of the two objects, (a) above, and the visual direction of the monocular areas, (b) above, are dependent upon the constraint that two opaque objects cannot be represented in the same direction. Demonstrations that readers can perform, and that support this argument, are provided on the Perception website at http://www.perceptionweb.com/perc0102/ono.html.     

Dodge-ing the issue: Dodge,Javal, Hering,and the measurement of saccades in eye-movement research

Dodge, in 1916, suggested that the French term 'saccade' should be used for describing the rapid movements of the eyes that occur while reading. Previously he had referred to these as type I movements. Javal had used the term 'saccade' in 1879, when describing experiments conducted in his laboratory by Lamare. Accordingly, Javal has been rightly credited with assigning the term to rapid eye movements. In English these rapid rotations had been called jerks, and they had been observed and measured before Lamare's studies of reading. Rapid sweeps of the eyes occur as one phase of nystagmus; they were observed by Wells in 1792 who used an afterimage technique, and they were illustrated by Crum Brown in 1878. Afterimages were used in nineteenth-century research on eye movements and eye position; they were also employed by Hering in 1879, to ascertain how the eyes moved during reading. In the previous year, Javal had employed afterimages in his investigations of reading, but this was to demonstrate that the eyes moved horizontally rather than vertically. Hering's and Lamare's auditory method established the discontinuous nature of eye movements during reading, and the photographic methods introduced by Dodge and others in the early twentieth century enabled their characteristics to be determined with greater accuracy.