Judgments of agency are affected by sensory noise without recruiting metacognitive processing

Going 'meta': a systematic review of metacognition and functional neurological disorder

In functional neurological disorder (FND), there is a fundamental disconnect between an apparently intact nervous system and the individuals' ability to consistently perform motor actions, perceive sensory signals and/or access effective cognition. Metacognition, the capacity to self-evaluate cognitive performance, appears highly relevant to FND pathophysiology. Poor metacognition is a potential mechanism via which abnormal models of self and the state of the world could arise and persist unchecked. There is therefore a justified enthusiasm that studies of metacognition may give substance to FND's intangible nature. However, many assume an impairment in metacognition even though experimental studies are still in their infancy. This systematic review provides an analytical checkpoint of the evidence after the first five years of experimental work. We firstly summarize current methods for testing metacognition, prerequisite knowledge that allows readers to independently evaluate the evidence. Using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, we then screened the 21 articles on this topic and review the experimental data of the eight studies that specifically tested metacognition in subjects with FND. Questionnaire metrics used to estimate global metacognition and general confidence in FND revealed a mixed picture of low or normal confidence. Of the five studies that used performance-controlled metrics, the gold-standard to estimate local metacognition in FND, four found metacognition to be equivalent to healthy controls and one paper supported impaired metacognition. We consequently try and broaden the debate and discuss alternative headline scenarios. We review how positive studies may offer insight and debate whether null studies could represent false negatives. However, since most studies find equivalent metacognition to controls, we also discuss whether metacognition could be intact and how this could inform mechanistic models of FND and have potential clinical utility. In summary, this review highlights signal of interest within the data, exposes current limitations and flags the many open questions.

The Body Knows Better: Sensorimotor signals reveal the interplay between implicit and explicit Sense of Agency in the human mind

Sense of Agency (SoA) is the feeling of control over our actions. SoA has been suggested to arise from both implicit sensorimotor integration as well as higher-level decision processes. SoA is typically measured by collecting participants' subjective judgments, conflating both implicit and explicit processing. Consequently, the interplay between implicit sensorimotor processing and explicit agency judgments is not well understood. Here, we evaluated in one exploratory and one preregistered experiment (N = 60), using a machine learning approach, the relation between a well-known mechanism of implicit sensorimotor adaptation and explicit SoA judgments. Specifically, we examined whether subjective judgments of SoA and sensorimotor conflicts could be inferred from hand kinematics in a sensorimotor task using a virtual hand (VH). In both experiments participants performed a hand movement and viewed a virtual hand making a movement that could either be synchronous with their action or include a parametric temporal delay. After each movement, participants judged whether their actual movement was congruent with the movement they observed. Our results demonstrated that sensorimotor conflicts could be inferred from implicit motor kinematics on a trial by trial basis. Moreover, detection of sensorimotor conflicts from machine learning models of kinematic data provided more accurate classification of sensorimotor congruence than participants' explicit judgments. These results were replicated in a second, preregistered, experiment. These findings show evidence of diverging implicit and explicit processing for SoA and suggest that the brain holds high-quality information on sensorimotor conflicts that is not fully utilized in the inference of conscious agency.

Communicated priors tune the perception of control

Action allows us to shape the world around us. But to act effectively we need to accurately sense what we can and cannot control. Classic theories across cognitive science suppose that this 'sense of agency' is constructed from the sensorimotor signals we experience as we interact with our surroundings. But these sensorimotor signals are inherently ambiguous, and can provide us with a distorted picture of what we can and cannot influence. Here we investigate one way that agents like us might overcome the inherent ambiguity of these signals: by combining noisy sensorimotor evidence with prior beliefs about control acquired through explicit communication with others. Using novel tools to measure and model control decisions, we find that explicit beliefs about the controllability of the environment alter both the sensitivity and bias of agentic choices; meaning that we are both better at detecting and more biased to feel control when we are told to expect it. These seemingly paradoxical effects on agentic choices can be captured by a computational model where expecting to be in control exaggerates the sensitivity or 'gain' of the mechanisms we use to detect our influence over our surroundings - making us increasingly sensitised to both true and illusory signs of agency. In combination, these results reveal a cognitive and computational mechanism that allows public communication about what we can and cannot influence to reshape our private sense of control.

Metacognition bridges experiences and beliefs in sense of agency

Cognitive scientists differentiate the "minimal self" - subjective experiences of agency and ownership in our sensorimotor interactions with the world - from declarative beliefs about the self that are sustained over time. However, it remains an open question how individual sensory experiences of agency are integrated into the belief ofbeing an agent.We administered a sensorimotor task to measure subjects' (n = 195) propensity to classify stimuli as self-caused and metacognitive monitoring of such judgements, and we compared these behavioral metrics to declarative beliefs about their agency. Subjects who were less sensitive to control cues also reported more negative agency beliefs, though positive beliefs were not clearly correlated with any sensorimotor measure. Importantly, this relationship between first-order sensitivity and declarative beliefs essentially disappears when controlling for metacognitive sensitivity. Results suggest agency beliefs are not related directly to the propensity to make positive agency judgements but are connected through introspective access.

Metacognition and sense of agency

Intelligent agents need to understand how they can change the world, and how they cannot change it, in order to make rational decisions for their forthcoming actions, and to adapt to their current environment. Previous research on the sense of agency, based largely on subjective ratings, failed to dissociate the sensitivity of sense of agency (i.e., the extent to which individual sense of agency tracks actual instrumental control over external events) from judgment criteria (i.e., the extent to which individuals self-attribute agency independent of their actual influence over external events). Furthermore, few studies have examined whether individuals have metacognitive access to the internal processes underlying the sense of agency. We developed a novel two-alternative-forced choice (2FAC) control detection task, in which participants identified which of two visual objects was more strongly controlled by their voluntary movement. The actual level of control over the target object was manipulated by adjusting the proportion of its motion that was driven by the participant's movement, compared to the proportion driven by a pre-recorded movement by another agent, using a staircase to hold 2AFC control detection accuracy at 70%. Participants identified which of the two visual objects they controlled, and also made a binary confidence judgment regarding their control detection judgment. We calculated a bias-free measure of first-order sensitivity (d') for detection control at any given level of participant's own movement. The proportion of pre-recorded movements determined by the stairecase could then be used as an index of control detection ability. We identified two distinct processes underlying first-order detection of control: one based on instantaneous sensory predictions for the current movement, and one based on detection of a regular motor-visual relation across a series of movements. Further, we found large individual differences across 40 particpants in metacognitive sensitivity (meta-d') even though first-order sensitivity of control detection was well controlled. Using structural equation modelling (SEM), we showed that metacognition was negatively correlated with the predictive process component of detection of control. This result is inconsistent with previous hypotheses that detection of control relies on metacognitive monitoring of a predictive circuit. Instead, it suggests that predictive mechanisms that compute sense of agency may operate unconsciously.

Multisensory decisions from self to world

Classic Bayesian models of perceptual inference describe how an ideal observer would integrate 'unisensory' measurements (multisensory integration) and attribute sensory signals to their origin(s) (causal inference). However, in the brain, sensory signals are always received in the context of a multisensory bodily state-namely, in combination with other senses. Moreover, sensory signals from both interoceptive sensing of one's own body and exteroceptive sensing of the world are highly interdependent and never occur in isolation. Thus, the observer must fundamentally determine whether each sensory observation is from an external (versus internal, self-generated) source to even be considered for integration. Critically, solving this primary causal inference problem requires knowledge of multisensory and sensorimotor dependencies. Thus, multisensory processing is needed to separate sensory signals. These multisensory processes enable us to simultaneously form a sense of self and form distinct perceptual decisions about the external world. In this opinion paper, we review and discuss the similarities and distinctions between multisensory decisions underlying the sense of self and those directed at acquiring information about the world. We call attention to the fact that heterogeneous multisensory processes take place all along the neural hierarchy (even in forming 'unisensory' observations) and argue that more integration of these aspects, in theory and experiment, is required to obtain a more comprehensive understanding of multisensory brain function. This article is part of the theme issue 'Decision and control processes in multisensory perception'.

Disentangling the Neural Correlates of Agency, Ownership and Multisensory Processing

The experience of the self as an embodied agent in the world is an essential aspect of human consciousness. This experience arises from the feeling of control over one's bodily actions, termed the Sense of Agency, and the feeling that the body belongs to the self, Body Ownership. Despite long-standing philosophical and scientific interest in the relationship between the body and brain, the neural systems involved in Body Ownership and Sense of Agency, and especially their interactions, are not yet understood. In this preregistered study using the Moving Rubber Hand Illusion inside an MR-scanner, we aimed to uncover the relationship between Body Ownership and Sense of Agency in the human brain. Importantly, by using both visuomotor and visuotactile stimulations and measuring online trial-by-trial fluctuations in the illusion magnitude, we were able to disentangle brain systems related to objective sensory stimulation and subjective judgments of the bodily-self. Our results indicate that at both the behavioral and neural levels, Body Ownership and Sense of Agency are strongly interrelated. Multisensory regions in the occipital and fronto-parietal regions encoded convergence of sensory stimulation conditions. The subjective judgments of the bodily-self were related to BOLD fluctuations in the Somatosensory cortex and in regions not activated by the sensory conditions, such as the insular cortex and precuneus. Our results highlight the convergence of multisensory processing in specific neural systems for both Body Ownership and Sense of Agency with partially dissociable regions for subjective judgments in regions of the Default Mode Network.

Impaired Metacognition of Voluntary Movement in Functional Movement Disorder

BACKGROUND

Motor symptoms in functional movement disorders (FMDs) are experienced as involuntary but share characteristics of voluntary action. Clinical and experimental evidence indicate alterations in monitoring, control, and subjective experience of self-performed movements.

OBJECTIVE

The objective of this study was to test the prediction that FMDs are associated with a reduced ability to make accurate (metacognitive) judgments about self-performed movements.

METHODS

We compared 24 patients with FMD (including functional gait disturbance, functional tremor, and functional tics) with 24 age- and sex-matched healthy control subjects in a novel visuomotor-metacognitive paradigm. Participants performed target-directed movements on a graphics tablet with restricted visual feedback, decided which of two visually presented trajectories was closer to their preceding movement, and reported their confidence in the visuomotor decision. We quantified individual metacognitive performance as participants' ability to assign high confidence preferentially to correct visuomotor decisions.

RESULTS

Patients and control subjects showed comparable motor performance, response accuracy, and use of the confidence scale. However, visuomotor sensitivity in the trajectory judgment was reduced in patients with FMD compared with healthy control subjects. Moreover, metacognitive performance was impaired in patients, that is, their confidence ratings were less predictive of the correctness of visuomotor decisions. Exploratory subgroup analyses suggest metacognitive deficits to be most pronounced in patients with a functional gait disturbance or functional tremor.

CONCLUSIONS

Patients with FMD exhibited deficits both when making visuomotor decisions about their own movements and in the metacognitive evaluation of these decisions. Reduced metacognitive insight into voluntary motor control may play a role in FMD pathophysiology and could lay the groundwork for new treatment strategies. © 2023 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Motor outcomes congruent with intentions may sharpen metacognitive representations

We can monitor our intentional movements and form explicit representations about our movements, allowing us to describe how we move our bodies. But it is unclear which information this metacognitive monitoring relies on. For example, when throwing a ball to hit a target, we might use the visual information about how the ball flew to metacognitively assess our performance. Alternatively, we might disregard the ball trajectory - given that it is not directly relevant to our goal - and metacognitively assess our performance based solely on whether we reached the goal of hitting the target. In two experiments we aimed to distinguish between these two alternatives and asked whether the distal outcome of a goal-directed action (hitting or missing a target) informs the metacognitive representations of our own movements. Participants performed a semi-virtual task where they moved their arm to throw a virtual ball at a target. After each throw, participants discriminated which of two ball trajectories displayed on the screen corresponded to the flight path of their throw and then rated their confidence in this decision. The task included two conditions that differed on whether the distal outcome of the two trajectories shown matched (congruent) or differed (incongruent). Participants were significantly more accurate in discriminating between the two trajectories, and responded faster in the incongruent condition and, accordingly, were significantly more confident on these trials. Crucially, we found significant differences in metacognitive performance (measured as meta-d'/d') between the two conditions only on successful trials, where the virtual ball had hit the target. These results indicate that participants successfully incorporated information about the outcome of the movement into both their discrimination and confidence responses. However, information about the outcome selectively sharpened the precision of confidence ratings only when the outcome of their throw matched their intention. We argue that these findings underline the separation between the different levels of information that may contribute to body monitoring, and we provide evidence that intentions might play a central role in metacognitive motor representations.

Impaired sense of agency and associated confidence in psychosis

The Sense of Agency (SoA), our sensation of control over our actions, is a fundamental mechanism for delineating the Self from the environment and others. SoA arises from implicit processing of sensorimotor signals as well as explicit higher-level judgments. Psychosis patients suffer from difficulties in the sense of control over their actions and accurate demarcation of the Self. Moreover, it is unclear if they have metacognitive insight into their aberrant abilities. In this pre-registered study, we examined SoA and its associated confidence judgments using an embodied virtual reality paradigm in psychosis patients and controls. Our results show that psychosis patients not only have a severely reduced ability for discriminating their actions but they also do not show proper metacognitive insight into this deficit. Furthermore, an exploratory analysis revealed that the SoA capacities allow for high levels of accuracy in clinical classification of psychosis. These results indicate that SoA and its metacognition are core aspects of the psychotic state and provide possible venues for understanding the underlying mechanisms of psychosis, that may be leveraged for novel clinical purposes.

Metacognitive Domains Are Not Aligned along a Dimension of Internal-External Information Source

It is still debated whether metacognition, or the ability to monitor our own mental states, relies on processes that are “domain-general” (a single set of processes can account for the monitoring of any mental process) or “domain-specific” (metacognition is accomplished by a collection of multiple monitoring modules, one for each cognitive domain). It has been speculated that two broad categories of metacognitive processes may exist: those that monitor primarily externally generated versus those that monitor primarily internally generated information. To test this proposed division, we measured metacognitive performance (using m-ratio, a signal detection theoretical measure) in four tasks that could be ranked along an internal-external axis of the source of information, namely memory, motor, visuomotor, and visual tasks. We found correlations between m-ratios in visuomotor and motor tasks, but no correlations between m-ratios in visual and visuomotor tasks, or between motor and memory tasks. While we found no correlation in metacognitive ability between visual and memory tasks, and a positive correlation between visuomotor and motor tasks, we found no evidence for a correlation between motor and memory tasks. This pattern of correlations does not support the grouping of domains based on whether the source of information is primarily internal or external. We suggest that other groupings could be more reflective of the nature of metacognition and discuss the need to consider other non-domain task-features when using correlations as a way to test the underlying shared processes between domains.