Dissociable Effect of Stimulus Fluency on Accuracy and Confidence in Perceptual Decision Making

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Webber, Alexis Kaitlyn
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Perceptual decision making relies on collecting evidence from stimuli to make an accurate judgement. The decision is accompanied by a sense of confidence based on the same evidence. Although the accuracy and confidence of a decision are often correlated, it is important to understand cases when they are dissociable. The goal of this study was to investigate qualities of the stimuli that lead to these cases. A dot motion experiment was performed where participants were asked to judge the direction of the motion and report their subsequent confidence in the decision. The motion of the dots was varied in two ways: the strength of signal was controlled by adjusting the tilt difference and the noise of the signal was controlled by adjusting the coherence of the motion. It was discovered that in cases with high coherence and low or medium tilt, confidence was higher, but accuracy was lower than cases with low or medium coherence and high tilt. From this it was concluded that coherence has more of an effect on confidence while tilt has more of an effect on accuracy, causing a dissociation between accuracy and confidence. These findings are important because they provide insight into cases of over and under confidence that can allow for us to better gauge the validity of the confidence judgement as it relates to accuracy depending on the qualities of signal strength and noise.
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Undergraduate Thesis
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