Jason Samaha of the Postle Lab Wins Award

The Psychology Department is pleased to announce that Jason Samaha, in Brad Postle’s lab, has won the 2017 Ann E. Kelley Fellowship in Behavioral Neuroscience Travel award. 

His abstract is below and he will present his poster at the Society for Neuroscience meeting in Washington, D.C. in November. 

Confidence amplifies serial dependence in perceptual decisions  - Jason Samaha, Missy Switzky, Bradley R. Postle

Over a century of psychophysical research has tacitly relied on the assumption that perceptual decisions are causally related to only the stimulus presented on the current trial. Recent research, however, has shown that stimuli seen several seconds prior, on a previous trial, can influence decisions about the current stimulus, a phenomenon known as serial dependence. Here, we investigated whether this effect was mediated by the observer’s subjective sense of confidence in the decision from the previous trial. We found that orientation decisions on the current trial were more strongly biased towards the previous trial’s orientation when the previous trial was perceived with high confidence. Crucially, a further manipulation that boosted confidence without changing task performance also led to the same effect, indicating that increased confidence, in and of itself, was sufficient for amplifying the impact of the previous trial on the current trial’s decision. In other words, this effect was not merely due to the fact that confidence typically correlates strongly with task performance. Mechanistically, serial dependence may be driven by residual neural activity in attractor networks with slow time constants, suggesting that confidence may provide top-down mediation of the rate of decay of information in such networks. Or, confidence may boost the overall activity in the population representing the previous trial’s stimulus such that this activity takes longer to return to baseline and can more readily influence decision making on the current trial. Because prestimulus oscillations in the alpha-band (8-13 Hz) are known to predict trial-to-trial variation in confidence, the current results suggest that the oscillatory state of spontaneous brain activity on previous trials can have distal effects on the current trial's decision. Regardless of mechanism, these results suggest that subjective confidence functions to enhance the perceived continuity of the visual environment.


This fellowship, honoring the legacy of Ann E. Kelley, supports the training of future generations of behavioral neuroscientists that embody Ann Kelley's passion for understanding the brain with the ultimate goal of using this knowledge to reduce human suffering

Dr. Kelley led an eminent career in which she made groundbreaking contributions to neuropsychopharmacology. She held faculty positions at the University of Bordeaux in France, Harvard University, Northeastern University, and the University of Wisconsin, where she was the Wisconsin Distinguished Neuroscience Professor, Professor of Psychiatry, and Director of the Neuroscience Training Program. She published over 130 peer-reviewed scientific papers and her work was funded continuously for over two decades by the National Institutes of Health and the National Science Foundation. She was recognized with a MERIT award from the National Institute on Drug Abuse, an invited lecture at a Nobel Symposium in Stockholm, and the Mika Salpeter Lifetime Achievement Award from the Society for Neuroscience. Dr. Kelley was a pioneer in science and launched the successful careers of a generation of neuroscientists through her mentoring and teaching.