The effects of extinction and an explicitly unpaired treatment on the reinforcing properties of a Pavlovian conditioned stimulus.

This series of experiments examined the effects of extinction and an explicitly unpaired treatment on the ability of a conditioned stimulus (CS) to function as a reinforcer. Rats were trained to lever press for food, exposed to pairings of a noise CS and food, and, finally, tested for their willingness to lever press for the CS in the absence of the food. Experiment 1 provided a demonstration of conditioned reinforcement (using controls that were only exposed to unpaired presentations of the CS and food) and showed that it was equivalent after one or four sessions of CS-food pairings. Experiments 2 and 3 showed that, after one session of CS-food pairings, repeated presentations of the CS alone reduced its reinforcing properties; but after four sessions of CS-food pairings, repeated presentations of the CS alone had no effect on these properties. Experiment 4 showed that, after four sessions of CS-food pairings, explicitly unpaired presentations of the CS and food completely undermined conditioned reinforcement. Finally, Experiment 5 provided within-experiment evidence that, after four sessions of CS-food pairings, the reinforcing properties of the CS were disrupted by explicitly unpaired presentations of the CS and food but spared by repeated presentations of the CS alone. Together, these findings indicate that the effectiveness of extinction in undermining the reinforcing properties of a CS depends on its level of conditioning; and that, where extinction fails to disrupt these properties, they are successfully undermined by an explicitly unpaired treatment. They are discussed with respect to findings in the literature on Pavlovian-to-instrumental transfer; and the Rescorla-Wagner model, which anticipates that an explicitly unpaired treatment will be more effective than extinction in reversing the effects of conditioning.

Amused, flirting or simply baffled? Is recognition of all emotions affected by traumatic brain injury?

OBJECTIVE: This study examined whether people with moderate-severe traumatic brain injury (TBI) display a specific or a general impairment in emotion recognition compared with matched controls, whether these deficits might be accounted for by deficits in other cognitive processes, and whether emotion recognition predicts social functioning following TBI. PARTICIPANTS: Thirty-two participants with TBI and 32 matched controls took part in this study. DESIGN: Participants completed the Complex Audio-Visual Emotion Assessment Task (CAVEAT), a novel measure of emotion recognition, alongside measures of neuropsychological functioning. The TBI group also completed selected self-report measures of psychosocial functioning. RESULTS: Traumatic brain injury participants performed more poorly than controls in recognizing all emotions, rather than displaying a selective impairment in recognizing some emotions (e.g., negative vs. positive) compared with others. Although abstract reasoning, working memory, and processing speed were associated with emotion recognition, injury severity and abstract reasoning were the sole predictors of emotion recognition as measured by the CAVEAT. Emotion recognition accuracy in the TBI group was associated with number of friends and self-reported apathy. CONCLUSION: Emotion recognition deficits are a direct consequence of TBI and have a direct effect on the social dysfunction which is a common outcome of TBI, strengthening the need for targeted remediation.