Biology subjects

Sherman, M. T.

Publications and source records attributed to Sherman, M. T..

3 recordsLinked to original sources

bioRxiv2020

Accumulation of salient events in sensory cortex activity predicts subjective time

Human experience of time exhibits systematic, context-dependent deviations from veridical clock time; for example, time is experienced differently at work than on holiday. Here we test the proposal that differences from clock time in subjective experience of time arise because time estimates are constructed by accumulating the same quantity that guides perception: salient events. Healthy human participants watched naturalistic, silent videos of up to [~]1 minute in duration and estimated their duration while fMRI was acquired. We were able to reconstruct trial-by-trial biases in participants duration reports, which reflect subjective experience of time (rather than veridical clock time), purely from salient events in their visual cortex BOLD activity. This was not the case for control regions in auditory and somatosensory cortex, despite being able to predict clock time from all three brain areas. Our results reveal that the information arising during sensory processing of our dynamic environment provides a sufficient basis for reconstructing human subjective time estimates.

neuroscience↗

bioRxiv2018

Domain-general enhancements of metacognitive ability through adaptive training

The metacognitive ability to introspect about self-performance varies substantially across individuals. Given that effective monitoring of performance is deemed important for effective behavioural control, intervening to improve metacognition may have widespread benefits, for example in educational and clinical settings. However, it is unknown whether and how metacognition can be systematically improved through training independently of task performance, or whether metacognitive improvements generalize across different task domains. Across 8 sessions, here we provided feedback to two groups of participants in a perceptual discrimination task: an experimental group (N = 29) received feedback on their metacognitive judgments, while an active control group (N = 32) received feedback on their decision performance only. Relative to the control group, adaptive training led to increases in metacognitive calibration (as assessed by Brier scores) which generalized both to untrained stimuli and an untrained task (recognition memory). Leveraging signal detection modeling we found that metacognitive improvements were driven both by changes in metacognitive efficiency (meta-d/d) and confidence level, and that later increases in metacognitive efficiency were positively mediated by earlier shifts in confidence. Our results reveal a striking malleability of introspection and indicate the potential for a domain-general enhancement of metacognitive abilities.

animal behavior and cognition↗

bioRxiv2018

Quantifying metacognitive thresholds using signal-detection theory

How sure are we about what we know? Confidence, measured via self-report, is often interpreted as a subjective probabilistic estimate on having made a correct judgement. The neurocognitive mechanisms underlying the construction of confidence and the information incorporated into these judgements are of increasing interest. Investigating these mechanisms requires principled and practically applicable measures of confidence and metacognition. Unfortunately, current measures of confidence are subject to distortions from decision biases and task performance. Motivated by a recent signal-detection theoretic behavioural measure of metacognitive sensitivity, known as meta-[d], here we present a quantitative behavioural measure of confidence that is invariant to decision bias and task performance. This measure, which we call m-distance, captures in a principled way the propensity to report decisions with high (or low) confidence. Computational simulations demonstrate the robustness of m-distance to decision bias and task performance, as well as its behaviour under conditions of high and low metacognitive sensitivity and under dual-channel and hierarchical models of metacognition. The introduction of the m-distance measure will enhance systematic quantitative studies of the behavioural expression and neurocognitive basis of subjective confidence.

neuroscience↗