Certain behaviors: Response selection and certainty-related processing in humans and rhesus monkeys
by Caio Margarido Moreira
Date of Examination:2016-07-13
Date of issue:2016-08-19
Advisor:Dr. Igor Kagan
Referee:Dr. Igor Kagan
Referee:Prof. Dr. Julia Fischer
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Description:Dissertation
Abstract
English
Humans and other animals constantly evaluate their decisions in order to learn and behave adaptively. Experimentally, such evaluation processes are accessed using metacognitive reports. When made after decisions, metacognitive reports might reflect not only different levels of decision certainty, but also two certainty directions (certainty of being correct and certainty of being incorrect). It is important to test if such bi-directional processing can be measured because, for adaptive decision-making, information about being incorrect is as important as information about being correct. We were able to capture bi-directional certainty readouts by asking subjects to bet money on their perceptual decision accuracy using a six-grade wager scale (post-decision wagering, PDW). To isolate trial-specific aspects of metacognitive judgments, we used pre-decision wagering trials (wagering before the perceptual decision) to subtract, from PDW trials, wagering influences resulting from non-trial-specific assessment of expected difficulty and psychological biases. This novel measure of metacognitive ability allowed independent quantification of certainty of being correct and certainty of being incorrect readouts. Bi-directional certainty readouts were associated with increased sensitivity during wagering in comparison to perceptual decisions (i.e. high metacognitive efficiency), suggesting a link between post-decisional evidence accumulation and metacognitive efficiency. We also show that both readouts increased on easier trials, demonstrating that certainty of being incorrect is not confounded with low certainty. The quantification of bi-directional certainty by the same implicit graded response scale suggests that both readouts represent similar, or even the same, metacognitive process.
Keywords: certainty, metacognition, post-decisional evidence, fMRI