Sensory prediction mechanisms in action

When we produce an action we generate predictions about the sensory consequences that are likely to ensue. This thesis tests a series of claims about the functional contribution these predictions make to perception, the role that such predictions play in processing the reactions of others, and the range of sensory inputs that these prediction mechanisms operate over. Chapter 1 outlines the theoretical background to each of these claims, alongside the previous literature that motivates subsequent experiments. The first three empirical chapters focus on claims about the functional role of sensory predictions during action: that they act to ‘cancel’ perception of expected action outcomes. Chapter 2 investigates this hypothesis in the context an intensity judgement task, Chapter 3 tests the hypothesis in the context of a signal detection task and Chapter 4 assess how predictions generated during action influence multivariate measures of visual brain activity, recorded via functional magnetic resonance imaging. Chapter 5 investigates the claim that sensory predictions during action support the processing of imitative reactions in others. Two psychophysical experiments are reported which investigate whether sensory predictions generated during action have temporal properties needed to support processing of others’ reactions. Chapter 6 investigates whether sensory predictions generated during action influence the ‘when’ - as well as the ‘what’ - of perception. Four psychophysical experiments investigate whether the temporal features of executed actions are incorporated into duration perception. Chapters 7 and 8 report preliminary investigations into the mechanism underlying these effects. Chapter 7 assesses whether these influences arise through a mechanism that is primarily tuned to biological action outcomes. Chapter 8 investigates whether these effects arise as a result of statistical learning about the relationship between actions and outcomes. Chapter 9 summarises the studies presented in the thesis, and outlines their implications for thinking about sensory prediction during action

Predicted action consequences are perceptually facilitated before cancellation

Models of action control suggest that predicted action outcomes are “cancelled” from perception, allowing agents to devote resources to more behaviorally relevant unexpected events. These models are supported by a range of findings demonstrating that expected consequences of action are perceived less intensely than unexpected events. A key assumption of these models is that the prediction is subtracted from the sensory input. This early subtraction allows preferential processing of unexpected events from the outset of movement, thereby promoting rapid initiation of corrective actions and updating of predictive models. We tested this assumption in three psychophysical experiments. Participants rated the intensity (brightness) of observed finger movements congruent or incongruent with their own movements at different timepoints after action. Across Experiments 1 and 2, evidence of cancellation—whereby congruent events appeared less bright than incongruent events—was only found 200 ms after action, whereas an opposite effect of brighter congruent percepts was observed in earlier time ranges (50 ms after action). Experiment 3 demonstrated that this interaction was not a result of response bias. These findings suggest that “cancellation” may not be the rapid process assumed in the literature, and that perception of predicted action outcomes is initially “facilitated.” We speculate that the representation of our environment may in fact be optimized via two opposing processes: The primary process facilitates perception of events consistent with predictions and thereby helps us to perceive what is more likely, but a later process aids the perception of any detected events generating prediction errors to assist model updating

Association between action kinematics and emotion perception across adolescence

Research with adults suggests that we interpret others’ internal states from kinematic cues, using models calibrated to our own action experiences. Changes in action production that occur during adolescence may therefore have implications for adolescents’ understanding of others. Here we examined whether, like adults, adolescents use velocity cues to determine others’ emotions, and whether any emotion perception differences would be those predicted based on differences in action production. We measured preferred walking velocity in groups of Early (11-12 years old), Middle (13-14 years old) and Late (16-18 years old) adolescents, and adults, and recorded their perception of happy, angry and sad ‘point-light walkers’. Preferred walking velocity decreased across age and ratings of emotional stimuli with manipulated velocity demonstrated that all groups used velocity cues to determine emotion. Importantly, the relative intensity ratings of different emotions also differed across development in a manner that was predicted based on the group differences in walking velocity. Further regression analyses demonstrated that emotion perception was predicted by own movement velocity, rather than age or pubertal stage per se. These results suggest that changes in action production across adolescence are indeed accompanied by corresponding changes in how emotions are perceived from velocity. These findings indicate the importance of examining differences in action production across development when interpreting differences in understanding of others

Sensory prediction mechanisms in action

When we produce an action we generate predictions about the sensory consequences that are likely to ensue. This thesis tests a series of claims about the functional contribution these predictions make to perception, the role that such predictions play in processing the reactions of others, and the range of sensory inputs that these prediction mechanisms operate over. Chapter 1 outlines the theoretical background to each of these claims, alongside the previous literature that motivates subsequent experiments. The first three empirical chapters focus on claims about the functional role of sensory predictions during action: that they act to ‘cancel’ perception of expected action outcomes. Chapter 2 investigates this hypothesis in the context an intensity judgement task, Chapter 3 tests the hypothesis in the context of a signal detection task and Chapter 4 assess how predictions generated during action influence multivariate measures of visual brain activity, recorded via functional magnetic resonance imaging. Chapter 5 investigates the claim that sensory predictions during action support the processing of imitative reactions in others. Two psychophysical experiments are reported which investigate whether sensory predictions generated during action have temporal properties needed to support processing of others’ reactions. Chapter 6 investigates whether sensory predictions generated during action influence the ‘when’ - as well as the ‘what’ - of perception. Four psychophysical experiments investigate whether the temporal features of executed actions are incorporated into duration perception. Chapters 7 and 8 report preliminary investigations into the mechanism underlying these effects. Chapter 7 assesses whether these influences arise through a mechanism that is primarily tuned to biological action outcomes. Chapter 8 investigates whether these effects arise as a result of statistical learning about the relationship between actions and outcomes. Chapter 9 summarises the studies presented in the thesis, and outlines their implications for thinking about sensory prediction during action

Perceptual prediction: rapidly making sense of a noisy world

Prior knowledge shapes what we perceive. A new brain stimulation study suggests that this perceptual shaping is achieved by changes in sensory brain regions before the input arrives, with common mechanisms operating across different sensory areas

Our own action kinematics predict the perceived affective states of others.

Our movement kinematics provideuseful cues aboutour affective states. Given that our experiences furnish models that help us to interpret our environment, and that a rich source of action experience comes from our own movements,the present study examined whetherwe use models of our own action kinematics to make judgments about the affective states of others. For example,relative to one’s typical kinematics, anger isassociated with fast movements. Therefore, the extent to which we perceive angerin others maybe determined by the degreeto which their movementsare faster than our own typicalmovements. We related participants’walking kinematicsin a neutral contextto their judgments of the affective statesconveyed byobserved point-light walkers(PLWs). Aspredicted,we found a linear relationship between one’s own walking kinematics and affective state judgments, such that faster participants rated sloweremotionsmore intensely relative to their ratings for faster emotions. This relationship was absent when observing PLWs where differences in velocity between affective states were removed. These findings suggest that perception of affective states in others is predicted by one’s own movement kinematics, withimportant implications for perception of, and interaction with,those who move differentl

Action biases perceptual decisions towards expected outcomes

We predict how our actions will influence the world around us. Prevailing models in the action control literature propose that we use these predictions to suppress or ‘cancel’ perception of expected action outcomes, to highlight more informative surprising events. However, contrasting normative Bayesian models in sensory cognition suggest that we are more, not less, likely to perceive what we expect–given that what we expect is more likely to occur. Here we adjudicated between these models by investigating how expectations influence perceptual decisions about action outcomes in a signal detection paradigm. Across three experiments, participants performed one of two manual actions that were sometimes accompanied by brief presentation of expected or unexpected visual outcomes.Contrary to dominant cancellation models but consistent with Bayesian accounts, we found that observers were biased to report the presence of expected action outcomes. There were no effects of expectation on sensitivity. Computational modelling revealed that the action-induced bias reflected a sensory bias in how evidence was accumulated rather than a baseline shift in decision circuits. Expectation effects remained in Experiments 2 and 3 when orthogonal cues indicated which finger was more likely to be probed (i.e.,task-relevant). These biases towards perceiving expected action outcomes are suggestive of a mechanism that would enable generation of largely veridical representations of our actions and their consequences in an inherently uncertain sensory world

Expectations about precision bias metacognition and awareness.

Bayesian models of the mind suggest that we estimate the reliability or “precision” of incoming sensory signals to guide perceptual inference and to construct feelings of confidence or uncertainty about what we are perceiving. However, accurately estimating precision is likely to be challenging for bounded systems like the brain. One way observers could overcome this challenge is to form expectations about the precision of their perceptions and use these to guide metacognition and awareness. Here we test this possibility. Participants made perceptual decisions about visual motion stimuli, while providing confidence ratings (Experiments 1 and 2) or ratings of subjective visibility (Experiment 3). In each experiment, participants acquired probabilistic expectations about the likely strength of upcoming signals. We found these expectations about precision altered metacognition and awareness—with participants feeling more confident and stimuli appearing more vivid when stronger sensory signals were expected, without concomitant changes in objective perceptual performance. Computational modeling revealed that this effect could be well explained by a predictive learning model that infers the precision (strength) of current signals as a weighted combination of incoming evidence and top-down expectation. These results support an influential but untested tenet of Bayesian models of cognition, suggesting that agents do not only “read out” the reliability of information arriving at their senses, but also take into account prior knowledge about how reliable or “precise” different sources of information are likely to be. This reveals that expectations about precision influence how the sensory world appears and how much we trust our senses

Atypical emotion recognition from bodies is associated with perceptual difficulties in healthy aging.

A range of processes are required for recognizing others’ affective states. It is particularly important that we process the perceptual cues providing information about these states. These experiments tested the hypothesis that difficulties with affective state identification in older adults (OAs) arise, at least partly, from deficits in perceptual processing. To this end we presented “point light display” whole body stimuli to healthy OAs and comparison younger adults (YAs) in 3 signal detection experiments. We examined the ability of OAs to recognize visual bodily information—posture and kinematics—and whether impaired recognition of affective states can be explained by deficits in processing these cues. OAs exhibited reduced sensitivity to postural cues (Experiment 1) but not to kinematic cues (Experiment 2) in affectively neutral stimuli. Importantly, they also exhibited reduced sensitivity only to affective states conveyed predominantly through posture (Experiment 3) —that is, the cue they were impaired in perceiving. These findings highlight how affective state identification difficulties in OAs may arise from problems in perceptual processing and demonstrate more widely how it is essential to consider the contribution of perceptual processes to emotion recognition. (APA PsycInfo Database Record (c) 2019 APA, all rights reserved

Learning to perceive and perceiving to learn

We thank Corlett for his thought-provoking response [1] to our recent article [2]. Corlett shares our concerns about inconsistencies in theories of perceptual prediction and highlights some reminiscent debates in learning theory. He also proposes why the perceptual prediction mechanisms may operate differently in the domain of action relative to other sensory cognition. Here, we highlight how we share the conviction that dialogue across disciplines will inform both models of perception and learning, but clarify that important distinctions between the explananda mean the theoretical puzzles are not reducible to each other. We also question whether action prediction mechanisms do indeed operate differently