Stephen M. Fleming

Relating Introspective Accuracy to Individual Differences in Brain Structure

Naval Gazing Simple perceptual tasks, such as detecting the contrast between light and dark bars in a grating, have been a mainstay of psychophysical research for decades. This kind of task makes it possible to obtain both an objective measure of how accurate subjects are and a subjective measure of how confident they are in their judgments. Fleming et al. (p. 1541; see the Perspective by Lau and Maniscalco) have taken this approach one step further by constructing a measure of how accurate subjects are in their confidence judgments. This capacity for introspection, which can be regarded as one facet of metacognition (thinking about thinking), is shown to vary across individuals and to correlate positively with the gray matter volume of the frontopolar cortex (the frontmost region of the brain) and also with white matter in the tracts of the corpus callosum that connect these regions in the left and right hemispheres. Individual differences in the capacity for introspection are reflected in structural variation in the frontal lobe. The ability to introspect about self-performance is key to human subjective experience, but the neuroanatomical basis of this ability is unknown. Such accurate introspection requires discriminating correct decisions from incorrect ones, a capacity that varies substantially across individuals. We dissociated variation in introspective ability from objective performance in a simple perceptual-decision task, allowing us to determine whether this interindividual variability was associated with a distinct neural basis. We show that introspective ability is correlated with gray matter volume in the anterior prefrontal cortex, a region that shows marked evolutionary development in humans. Moreover, interindividual variation in introspective ability is also correlated with white-matter microstructure connected with this area of the prefrontal cortex. Our findings point to a focal neuroanatomical substrate for introspective ability, a substrate distinct from that supporting primary perception.

The Neural Basis of Metacognitive Ability

Ability in various cognitive domains is often assessed by measuring task performance, such as the accuracy of a perceptual categorization. A similar analysis can be applied to metacognitive reports about a task to quantify the degree to which an individual is aware of his or her success or failure. Here, we review the psychological and neural underpinnings of metacognitive accuracy, drawing on research in memory and decision-making. These data show that metacognitive accuracy is dissociable from task performance and varies across individuals. Convergent evidence indicates that the function of the rostral and dorsal aspect of the lateral prefrontal cortex (PFC) is important for the accuracy of retrospective judgements of performance. In contrast, prospective judgements of performance may depend upon medial PFC. We close with a discussion of how metacognitive processes relate to concepts of cognitive control, and propose a neural synthesis in which dorsolateral and anterior prefrontal cortical subregions interact with interoceptive cortices (cingulate and insula) to promote accurate judgements of performance.

Confidence in value-based choice

Decisions are never perfect, with confidence in ones choices fluctuating over time. How subjective confidence and valuation of choice options interact at the level of brain and behavior is unknown. Using a dynamic model of the decision process, we show that confidence reflects the evolution of a decision variable over time, explaining the observed relation between confidence, value, accuracy and reaction time. As predicted by our dynamic model, we show that a functional magnetic resonance imaging signal in human ventromedial prefrontal cortex (vmPFC) reflects both value comparison and confidence in the value comparison process. Crucially, individuals varied in how they related confidence to accuracy, allowing us to show that this introspective ability is predicted by a measure of functional connectivity between vmPFC and rostrolateral prefrontal cortex. Our findings provide a mechanistic link between noise in value comparison and metacognitive awareness of choice, enabling us both to want and to express knowledge of what we want.

How to measure metacognition.

The ability to recognize ones own successful cognitive processing, in e.g., perceptual or memory tasks, is often referred to as metacognition. How should we quantitatively measure such ability? Here we focus on a class of measures that assess the correspondence between trial-by-trial accuracy and ones own confidence. In general, for healthy subjects endowed with metacognitive sensitivity, when one is confident, one is more likely to be correct. Thus, the degree of association between accuracy and confidence can be taken as a quantitative measure of metacognition. However, many studies use a statistical correlation coefficient (e.g., Pearsons r) or its variant to assess this degree of association, and such measures are susceptible to undesirable influences from factors such as response biases. Here we review other measures based on signal detection theory and receiver operating characteristics (ROC) analysis that are “bias free,” and relate these quantities to the calibration and discrimination measures developed in the probability estimation literature. We go on to distinguish between the related concepts of metacognitive bias (a difference in subjective confidence despite basic task performance remaining constant), metacognitive sensitivity (how good one is at distinguishing between ones own correct and incorrect judgments) and metacognitive efficiency (a subjects level of metacognitive sensitivity given a certain level of task performance). Finally, we discuss how these three concepts pose interesting questions for the study of metacognition and conscious awareness.

Prefrontal contributions to metacognition in perceptual decision-making

Neuroscience has made considerable progress in understanding the neural substrates supporting cognitive performance in a number of domains, including memory, perception, and decision making. In contrast, how the human brain generates metacognitive awareness of task performance remains unclear. Here, we address this question by asking participants to perform perceptual decisions while providing concurrent metacognitive reports during fMRI scanning. We show that activity in right rostrolateral prefrontal cortex (rlPFC) satisfies three constraints for a role in metacognitive aspects of decision-making. Right rlPFC showed greater activity during self-report compared to a matched control condition, activity in this region correlated with reported confidence, and the strength of the relationship between activity and confidence predicted metacognitive ability across individuals. In addition, functional connectivity between right rlPFC and both contralateral PFC and visual cortex increased during metacognitive reports. We discuss these findings in a theoretical framework where rlPFC re-represents object-level decision uncertainty to facilitate metacognitive report.

Overcoming status quo bias in the human brain

Humans often accept the status quo when faced with conflicting choice alternatives. However, it is unknown how neural pathways connecting cognition with action modulate this status quo acceptance. Here we developed a visual detection task in which subjects tended to favor the default when making difficult, but not easy, decisions. This bias was suboptimal in that more errors were made when the default was accepted. A selective increase in subthalamic nucleus (STN) activity was found when the status quo was rejected in the face of heightened decision difficulty. Analysis of effective connectivity showed that inferior frontal cortex, a region more active for difficult decisions, exerted an enhanced modulatory influence on the STN during switches away from the status quo. These data suggest that the neural circuits required to initiate controlled, nondefault actions are similar to those previously shown to mediate outright response suppression. We conclude that specific prefrontal-basal ganglia dynamics are involved in rejecting the default, a mechanism that may be important in a range of difficult choice scenarios.

The development of metacognitive ability in adolescence

Highlights ► Metacognition refers to the knowledge we have of our own cognitive processes. ► We investigated the development of metacognition between 11 and 41 years. ► Participants carried out a visual decision task and rated confidence in their decisions. ► While task performance was stable, metacognition improved between 11 and 17. ► Metacognition shows a prolonged developmental trajectory during adolescence.

Metacognition: Computation, biology and function

Many complex systems maintain a self-referential check and balance. In animals, such reflective monitoring and control processes have been grouped under the rubric of metacognition. In this introductory article to a Theme Issue on metacognition, we review recent and rapidly progressing developments from neuroscience, cognitive psychology, computer science and philosophy of mind. While each of these areas is represented in detail by individual contributions to the volume, we take this opportunity to draw links between disciplines, and highlight areas where further integration is needed. Specifically, we cover the definition, measurement, neurobiology and possible functions of metacognition, and assess the relationship between metacognition and consciousness. We propose a framework in which level of representation, order of behaviour and access consciousness are orthogonal dimensions of the conceptual landscape.

Subliminal priming of actions influences sense of control over effects of action

The experience of controlling ones own actions, and through them events in the outside world, is a pervasive feature of human mental life. Two experiments investigated the relation between this sense of control and the internal processes involved in action selection and cognitive control. Action selection was manipulated by subliminally priming left or right keypress actions in response to a supraliminal visual target. The action caused the display of one of several colours as an action effect. The specific colour shown depended on whether the participants action was compatible or incompatible with the preceding subliminal prime, and not on the prime identity alone. Unlike previous studies, therefore, the primes did not predict the to-be-expected action effects. Participants rated how much control they experienced over the different colours. Replicating previous results, compatible primes facilitated responding, whereas incompatible primes interfered with response selection. Crucially, priming also modulated the sense of control over action effects: participants experienced more control over colours produced by actions that were compatible with the preceding prime than over colours associated with prime-incompatible actions. Experiment 2 showed that this effect was not solely due to priming modulating action-effect contingencies. These results suggest that sense of control is linked to processes of selection between alternative actions, being strongest when selection is smooth and uncontested.

Domain-specific impairment in metacognitive accuracy following anterior prefrontal lesions

Convergent evidence supports a role for anterior prefrontal cortex (PFC) in metacognition—the capacity to evaluate cognitive processes—but whether metacognition relies on global or domain-specific substrates is unknown. Fleming et al. report that patients with anterior PFC lesions show impaired perceptual metacognition despite intact memory metacognition, supporting a domain-specific account.