Task-evoked Pupillary Responses Research Articles

The Effects of Light Level and Signal-to-Noise Ratio on the Task-Evoked Pupil Response in a Speech-in-Noise Task.

There is increasing interest in the measurement of cognitive effort during listening tasks, for both research and clinical purposes. Quantification of task-evoked pupil responses (TEPRs) is a psychophysiological method that can be used to study cognitive effort. However, light level during cognitively demanding listening tasks may affect TEPRs, complicating interpretation of listening-related changes. The objective of this study was to examine the effects of light level on TEPRs during effortful listening across a range of signal-to-noise ratios (SNRs). Thirty-six adults without hearing loss were asked to repeat target sentences presented in background babble noise while their pupil diameter was recorded. Light level and SNRs were manipulated in a 4 × 4 repeated-measures design. Repeated-measures analyses of variance were used to measure the effects. Peak and mean dilation were typically larger in more adverse SNR conditions (except for SNR -6 dB) and smaller in higher light levels. Differences in mean and peak dilation between SNR conditions were larger in dim light than in brighter light. Brighter light conditions make TEPRs less sensitive to variations in listening effort across levels of SNR. Therefore, light level must be considered and reported in detail to ensure sensitivity of TEPRs and for comparisons of findings across different studies. It is recommended that TEPR testing be conducted in relatively low light conditions, considering both background illumination and screen luminance. https://doi.org/10.23641/asha.25676538.

Music in the eye of the beholder: a pupillometric study on preferred background music, attentional state, and arousal.

Although background music listening during attention-demanding tasks is common, there is little research on how it affects fluctuations in attentional state and how these fluctuations are linked to physiological arousal. The present study built on Kiss and Linnell (2021) - showing a decrease in mind-wandering and increase in task-focus states with background music - to explore the link between attentional state and arousal with and without background music. 39 students between the ages of 19-32 completed a variation of the Psychomotor Vigilance Task in silence and with their self-selected background music (music they would normally listen to during attention-demanding tasks). Objective arousal measures (pretrial pupil diameter and task-evoked pupillary responses) and subjective attentional state measures (mind-wandering, task-focus, and external-distraction states) were collected throughout the task. Results showed a link between attentional state and arousal and indicated that background music increased arousal. Importantly, arousal mediated the effect of music to decrease mind-wandering and increase task-focus attentional states, suggesting that the arousal increase induced by music was behind the changes in attentional states. These findings show, for the first time in the context of background music listening, that there is a link between arousal and attentional state.

Are the P600 and P3 ERP components linked to the task-evoked pupillary response as a correlate of norepinephrine activity?

During language comprehension, anomalies and ambiguities in the input typically elicit the P600 event-related potential component. Although traditionally interpreted as a specific signal of combinatorial operations in sentence processing, the component has alternatively been proposed to be a variant of the oddball-sensitive, domain-general P3 component. In particular, both components might reflect phasic norepinephrine release from the locus coeruleus (LC/NE) to motivationally significant stimuli. In this preregistered study, we tested this hypothesis by relating both components to the task-evoked pupillary response, a putative biomarker of LC/NE activity. 36 participants completed a sentence comprehension task (containing 25% morphosyntactic violations) and a non-linguistic oddball task (containing 20% oddballs), while the EEG and pupil size were co-registered. Our results showed that the task-evoked pupillary response and the ERP amplitudes of both components were similarly affected by both experimental tasks. In the oddball task, there was also a temporally specific relationship between the P3 and the pupillary response beyond the shared oddball effect, thereby further linking the P3 to NE. Because this link was less reliable in the linguistic context, we did not find conclusive evidence for or against a relationship between the P600 and the pupillary response. Still, our findings further stimulate the debate on whether language-related ERPs are indeed specific to linguistic processes or shared across cognitive domains. However, further research is required to verify a potential link between the two ERP positivities and the LC/NE system as the common neural generator.

Effect of recurrent task-induced acute stress on task performance, vagally mediated heart rate variability, and task-evoked pupil response

Advances in wearable sensor technologies can be leveraged to investigate behavioral and physiological responses in task-induced stress environments. Reliable and valid multidimensional assessments are required to detect stress given its multidimensional nature. This study investigated the effect of recurrent task-induced acute stress on task performance, vagally mediated heart variability measures (vmHRV) and task-evoked pupillary response (TEPR). Task performance, vmHRV measures, and TEPR were collected from 32 study participants while they performed a computer-based task in a recurrent task-induced acute stress environment. Mixed-effects modeling was used to assess the sensitivity of each outcome variable to experimental conditions. Repeated measures correlation tests were used to examine associations between outcome variables. Task performance degraded under stress. vmHRV measures were lower in the stress conditions relative to the no stress conditions. TEPR was found to be higher in the stress conditions compared to the no stress conditions. Task performance was negatively associated with the vmHRV measures, and degraded task performance was linked to increased TEPR in the stress conditions. There were positive associations between vmHRV measures. TEPR was negatively associated with vmHRV measures. Although task-induced stress degrades task performance, recurrent exposure to that stress could alter this effect via habituation. Further, our findings suggest that vmHRV measures and TEPR are sensitive enough to quantify psychophysiological responses to recurrent task-induced stress.

Pupillary correlates of individual differences in n-back task performance.

We used pupillometry during a 2-back task to examine individual differences in the intensity and consistency of attention and their relative role in a working memory task. We used sensitivity, or the ability to distinguish targets (2-back matches) and nontargets, as the measure of task performance; task-evoked pupillary responses (TEPRs) as the measure of attentional intensity; and intraindividual pretrial pupil variability as the measure of attentional consistency. TEPRs were greater on target trials compared with nontarget trials, although there was no difference in TEPR magnitude when participants answered correctly or incorrectly to targets. Importantly, this effect interacted with performance: high performers showed a greater separation in their TEPRs between targets and nontargets, whereas there was little difference for low performers. Further, in regression analysis, larger TEPRs on target trials predicted better performance, whereas larger TEPRs on nontarget trials predicted worse performance. Sensitivity positively correlated with average pretrial pupil diameter and negatively correlated with intraindividual variability in pretrial pupil diameter. Overall, we found evidence that both attentional intensity (TEPRs) and consistency (pretrial pupil variation) predict performance on an n-back working memory task.

Effects of linguistic context and noise type on speech comprehension.

Understanding speech in background noise is an effortful endeavor. When acoustic challenges arise, linguistic context may help us fill in perceptual gaps. However, more knowledge is needed regarding how different types of background noise affect our ability to construct meaning from perceptually complex speech input. Additionally, there is limited evidence regarding whether perceptual complexity (e.g., informational masking) and linguistic complexity (e.g., occurrence of contextually incongruous words) interact during processing of speech material that is longer and more complex than a single sentence. Our first research objective was to determine whether comprehension of spoken sentence pairs is impacted by the informational masking from a speech masker. Our second objective was to identify whether there is an interaction between perceptual and linguistic complexity during speech processing. We used multiple measures including comprehension accuracy, reaction time, and processing effort (as indicated by task-evoked pupil response), making comparisons across three different levels of linguistic complexity in two different noise conditions. Context conditions varied by final word, with each sentence pair ending with an expected exemplar (EE), within-category violation (WV), or between-category violation (BV). Forty young adults with typical hearing performed a speech comprehension in noise task over three visits. Each participant heard sentence pairs presented in either multi-talker babble or spectrally shaped steady-state noise (SSN), with the same noise condition across all three visits. We observed an effect of context but not noise on accuracy. Further, we observed an interaction of noise and context in peak pupil dilation data. Specifically, the context effect was modulated by noise type: context facilitated processing only in the more perceptually complex babble noise condition. These findings suggest that when perceptual complexity arises, listeners make use of the linguistic context to facilitate comprehension of speech obscured by background noise. Our results extend existing accounts of speech processing in noise by demonstrating how perceptual and linguistic complexity affect our ability to engage in higher-level processes, such as construction of meaning from speech segments that are longer than a single sentence.

Attention Mobilization as a Modulator of Listening Effort: Evidence From Pupillometry.

Listening to speech in noise can require substantial mental effort, even among younger normal-hearing adults. The task-evoked pupil response (TEPR) has been shown to track the increased effort exerted to recognize words or sentences in increasing noise. However, few studies have examined the trajectory of listening effort across longer, more natural, stretches of speech, or the extent to which expectations about upcoming listening difficulty modulate the TEPR. Seventeen younger normal-hearing adults listened to 60-s-long audiobook passages, repeated three times in a row, at two different signal-to-noise ratios (SNRs) while pupil size was recorded. There was a significant interaction between SNR, repetition, and baseline pupil size on sustained listening effort. At lower baseline pupil sizes, potentially reflecting lower attention mobilization, TEPRs were more sustained in the harder SNR condition, particularly when attention mobilization remained low by the third presentation. At intermediate baseline pupil sizes, differences between conditions were largely absent, suggesting these listeners had optimally mobilized their attention for both SNRs. Lastly, at higher baseline pupil sizes, potentially reflecting overmobilization of attention, the effect of SNR was initially reversed for the second and third presentations: participants initially appeared to disengage in the harder SNR condition, resulting in reduced TEPRs that recovered in the second half of the story. Together, these findings suggest that the unfolding of listening effort over time depends critically on the extent to which individuals have successfully mobilized their attention in anticipation of difficult listening conditions.

Impact of light on task-evoked pupil responses during cognitive tasks.

Light has many non-image-forming functions including modulation of pupil size and stimulation of alertness and cognition. Part of these non-image-forming effects may be mediated by the brainstem locus coeruleus. The processing of sensory inputs can be associated with a transient pupil dilation that is likely driven in part by the phasic activity of the locus coeruleus. In the present study, we aimed to characterise the task-evoked pupil response associated with auditory inputs under different light levels and across two cognitive tasks. We continuously monitored the pupil of 20 young healthy participants (mean [SD] 24.05 [4.0] years; 14 women) whilst they completed an attentional and an emotional auditory task whilst exposed to repeated 30-40-s blocks of light interleaved with darkness periods. Blocks could either consist of monochromatic orange light (0.16 melanopic equivalent daylight illuminance (EDI) lux) or blue-enriched white light of three different levels [37, 92, 190 melanopic EDI lux; 6500 K]. For the analysis, 15 and then 14 participants were included in the attentional and emotional tasks, respectively. Generalised linear mixed models showed a significant main effect of light level on the task-evoked pupil responses triggered by the attentional and emotional tasks (p ≤ 0.0001). The impact of light was different for the target versus non-target stimulus of the attentional task but was not different for the emotional and neutral stimulus of the emotional task. There is a smaller sustained pupil size during brighter light blocks but, a higher light level triggers a stronger task-evoked pupil response to auditory stimulation, presumably through the recruitment of the locus coeruleus.

Dysregulated noradrenergic response is associated with symptom severity in individuals with schizophrenia.

The locus coeruleus-noradrenaline (LC-NA) system is involved in a wide range of cognitive functions and may be altered in schizophrenia. A non-invasive method to indirectly measure LC activity is task-evoked pupillary response. Individuals with schizophrenia present reduced pupil dilation compared to healthy subjects, particularly when task demand increases. However, the extent to which alteration in LC activity contributes to schizophrenia symptomatology remains largely unexplored. We aimed to investigate the association between symptomatology, cognition, and noradrenergic response in individuals with schizophrenia. We assessed task-evoked pupil dilation during a pro- and antisaccade task in 23 individuals with schizophrenia and 28 healthy subjects. Both groups showed similar preparatory pupil dilation during prosaccade trials, but individuals with schizophrenia showed significantly lower pupil dilation compared to healthy subjects in antisaccade trials. Importantly, reduced preparatory pupil dilation for antisaccade trials was associated with worse general symptomatology in individuals with schizophrenia. Our findings suggest that changes in LC-NA activity - measured by task-evoked pupil dilation - when task demand increases is associated with schizophrenia symptoms. Interventions targeting the modulation of noradrenergic responses may be suitable candidates to reduce schizophrenia symptomatology.

Pupil Dilation as an Index of Examinee's Cognitive Load in Answering a Mathematics Question: A Comparison Study of Different Approaches

ABSTRACTStudies have demonstrated that task‐evoked pupillary responses (TEPRs) can be adopted to measure the examinee's cognitive load. This study compared three approaches for the measurement of TEPRs, mean pupil diameter, mean pupil dilation, and mean percentage of pupil dilation, to determine the best‐fit measuring method. The valid participants of this study were eight sixth‐grade elementary students. The experimental materials used were two mathematics questions with differing difficulty. The generalized estimating equation (GEE) was employed to compare the goodness of fit of each approach. The results revealed that the measurement of TEPRs based on the mean percentage of pupil dilation measured every 4 s provided the best fit.

Children's listening effort for L2-accented speech

Speech perception is a complex task that can become challenging in certain conditions, such as listening to speech in unfamiliar accents. Using task-evoked pupillary response (TEPR) and dual-task procedures, prior research has shown that adults recruit additional cognitive resources when processing fully intelligible L2-accented speech compared to speech in their own L1 accent (McLaughlin and Van Engen, 2020; Brown et al., 2020). In the current study, we used pupillometry to investigate this effect in children (n = 35, ages 5;0 – 8;11) and ask whether prosodic variation can explain any differences in listening effort. Using Growth Curve Analysis, we found that unlike adults, children do not appear to recruit extra cognitive resources to process intelligible L2-accented speech. Like adults, however, pupillary response declined more rapidly for L2-accented speech across the experiment than for L1-accented speech, indicating either rapid adaptation or fatigue. Additionally, we identified three prosodic measures (relative word duration, pitch stability, and pitch range) that were related to speech adaptation/fatigue for both accent conditions, but in opposite directions. Although children do not appear to upregulate listening effort for L2-accented speech like adults, they appear to use prosodic cues differently for L1- versus L2- accented speech as they adapt to speech.

Investigating Human Physiological Responses to Work-Related Stress

Studies have shown that work-related stress is one of the causes of employee burnout, fatigue, and cognitive dysfunction, among other negative effects. Physiological features have been used to investigate stress, but more knowledge is needed in understanding physiological indicators of work-related stress. Moreover, to the best of our knowledge, no study is available that integrates both pupillometry and heart rate in investigating work-related stress. We, therefore, utilized task-evoked pupillary response (TEPR) from pupillometry and heart rate (HR), in the assessment of physiological responses of 32 subjects during the performance of Multi-Attribute Task Battery-II consisting of working baseline and stress conditions. A comparison of results of both conditions showed that TEPR and mean HR significantly increased during stress condition, as compared to working baseline condition. These results are attributed to the work related-stressors integrated in our study, thereby bolstering the applicability of heart rate and pupillometry in studies of work-related stress.

Competition and reward structures nearly eliminate time-on-task performance decrements: Implications for theories of vigilance and mental effort.

Across four experiments, we manipulated features of a simple reaction time (RT) task to examine the effects of such features on sustained attention. In Experiment 1, we created simple RT "game" that pitted participants against two computerized avatars. In one condition, participants were awarded points, while the other condition did not receive points. Performance in the two conditions did not differ, but both conditions showed shorter RTs and shallower time-on-task performance decrements compared to a standard psychomotor vigilance task. In Experiment 2, we removed the competitive feature but retained the point system. In this case, participants without a point system showed a steeper performance decrement than those with a point system. Experiments 3 and 4 replicated these effects and corroborated their findings with pupillometry. Participants in both conditions of Experiment 3 (competitive task) and the points condition of Experiment 4 showed larger task-evoked pupillary responses than participants in the no-points condition of Experiment 4. These findings challenge the notion that time-on-task performance decrements are caused by resource depletion (Smit et al., 2004) and are better explained by motivational control (Hockey, 2011) or cost-benefit theories (Boksem & Tops, 2008; Kurzban et al., 2013) of mental effort and sustained attention. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Nonlinear changes in pupillary attentional orienting responses across the lifespan

The cognitive aging process is not necessarily linear. Central task-evoked pupillary responses, representing a brainstem-pupil relationship, may vary across the lifespan. Thus we examined, in 75 adults ranging in age from 19 to 86, whether task-evoked pupillary responses to an attention task may serve in as an index of cognitive aging. This is because the locus coeruleus (LC), located in the brainstem, is not only among the earliest sites of degeneration in pathological aging, but also supports both attentional and pupillary behaviors. We assessed brief, task-evoked phasic attentional orienting to behaviorally relevant and irrelevant auditory tones, stimuli known specifically to recruit the LC in the brainstem and evoke pupillary responses. Due to potential nonlinear changes across the lifespan, we used a novel data-driven analysis on 6 dynamic pupillary behaviors on 10% of the data to reveal cut off points that best characterized the three age bands: young (19–41 years old), middle aged (42–68 years old), and older adults (69 + years old). Follow-up analyses on independent data, the remaining 90%, revealed age-related changes such as monotonic decreases in tonic pupillary diameter and dynamic range, along with curvilinear phasic pupillary responses to the behaviorally relevant target events, increasing in the middle-aged group and then decreasing in the older group. Additionally, the older group showed decreased differentiation of pupillary responses between target and distractor events. This pattern is consistent with potential compensatory LC activity in midlife that is diminished in old age, resulting in decreased adaptive gain. Beyond regulating responses to light, pupillary dynamics reveal a nonlinear capacity for neurally mediated gain across the lifespan, thus providing evidence in support of the LC adaptive gain hypothesis.

Copresence Was Found to Be Related to Some Pupil Measures in Persons With Hearing Loss While They Performed a Speech-in-Noise Task.

To assess if a manipulation of copresence was related to speech-in-noise task performance, arousal, and effort of persons with hearing loss. Task-related arousal and effort were measured by means of pupillometry. Twenty-nine participants (mean age: 64.6 years) with hearing loss (4-frequency pure-tone average [4F-PTA] of 50.2 dB HL [SD = 8.9 dB] in the right ear and 51.3 dB HL [SD = 8.7 dB] in the left ear; averaged across 0.5, 1, 2, and 4 kHz) listened to and repeated spoken Danish sentences that were masked by four streams of continuous speech. Participants were presented with blocks of 20 sentences, during which copresence was manipulated by having participants do the task either alone or accompanied by two observers who were recruited from a similar age group. The task was presented at two difficulty levels, which was accomplished by fixing the signal-to-noise ratio of the speech and masker to match the thresholds at which participants were estimated to correctly repeat 50% (difficult) or 80% (easy) of the sentences in a block. Performance was assessed based on whether or not sentences were repeated correctly. Measures of pupil size (baseline pupil size [BPS], peak pupil dilation [PPD], and mean pupil dilation [MPD]) were used to index arousal and effort. Participants also completed ratings of subjective effort and stress after each block of sentences and a self-efficacy for listening-questionnaire. Task performance was not associated with copresence, but was found to be related to 4F-PTA. An increase in BPS was found for copresence conditions, compared to alone conditions. Furthermore, a post-hoc exploratory analysis revealed that the copresence conditions were associated with a significantly larger pupil size in the second half of the task-evoked pupil response (TEPR). No change in PPD or MPD did was detected between copresence and alone conditions. Self-efficacy, 4F-PTA, and age were not found to be related to the pupil data. Subjective ratings were sensitive to task difficulty but not copresence. Copresence was not found to be related to speech-in-noise performance, PPD, or MPD in persons with HL but was associated with an increase in arousal (as indicated by a larger BPS). This could be related to premobilization of effort and/or discomfort in response to the observers' presence. Furthermore, an exploratory analysis of the pupil data showed that copresence was associated with greater pupil dilations in the second half of the TEPR. This may indicate that participants invested more effort during the speech-in-noise task while in the presence of the observers, but that this increase in effort may not necessarily have been related to listening itself. Instead, other speech-in-noise task-related processes, such as preparing to respond, could have been influenced by copresence.

Examining the feasibility of integrating pupillometry measures of listening effort into clinical audiology assessments

Pure-tone thresholds are often a poor predictor of hearing difficulties experienced by patients in audiology clinics. Approximately 25 million Americans may experience hearing difficulties despite having audiometric thresholds within normal limits. Pupil diameter increases with increasing listening effort and could provide an objective measure for determining the presence of such subclinical hearing problems. However, the cost and technical requirements of research-grade eye trackers have limited their use in audiology clinics. This study aims to determine the feasibility of using a commercially-available head mounted display (HMD) with integrated eye tracking to collect pupillometry measures during audiological testing. Pupillary data were collected for N = 46 younger normal-hearing adults while they completed clinically-relevant tests including pure tone audiometry, gaps-in-noise (GIN), dichotic digits, and speech-in-noise tests. Across tasks, task-evoked pupillary responses were generally sensitive to differences in listening demands. Results suggest audiologic testing with commercial HMD eye trackers is feasible and provides additional objective information related to listening effort that may help clinicians better understand and address patient needs. [The views expressed in this abstract are those of theauthors and do not reflect the official policy of the Department of Army/Navy/Air Force, Department of Defense, or U.S. Government.]

Using Task-Evoked Pupillary Response to Predict Clinical Performance during a Simulation Training

Training in healthcare skills can be affected by trainees' workload when completing a task. Due to cognitive processing demands being negatively correlated to clinical performance, assessing mental workload through objective measures is crucial. This study aimed to investigate task-evoked changes in pupil size as reliable markers of mental workload and clinical performance. A sample of 49 nursing students participated in a cardiac arrest simulation-based practice. Measurements of cognitive demands (NASA-Task Load Index), physiological parameters (blood pressure, oxygen saturation, and heart rate), and pupil responses (minimum, maximum, and difference diameters) throughout revealed statistically significant differences according to performance scores. The analysis of a multiple regression model produced a statistically significant pattern between pupil diameter differences and heart rate, systolic blood pressure, workload, and performance (R2 = 0.280; F (6, 41) = 2.660; p < 0.028; d = 2.042). Findings suggest that pupil variations are promising markers to complement physiological metrics for predicting mental workload and clinical performance in medical practice.

Give me a break! Unavoidable fatigue effects in cognitive pupillometry.

Pupillometry has a rich history in the study of perception and cognition. One perennial challenge is that the magnitude of the task-evoked pupil response diminishes over the course of an experiment, a phenomenon we refer to as a fatigue effect. Reducing fatigue effects may improve sensitivity to task effects and reduce the likelihood of confounds due to systematic physiological changes over time. In this paper, we investigated the degree to which fatigue effects could be ameliorated by experimenter intervention. In Experiment 1, we assigned participants to one of three groups-no breaks, kinetic breaks (playing with toys, but no social interaction), or chatting with a research assistant-and compared the pupil response across conditions. In Experiment 2, we additionally tested the effect of researcher observation. Only breaks including social interaction significantly reduced the fatigue of the pupil response across trials. However, in all conditions we found robust evidence for fatigue effects: that is, regardless of protocol, the task-evoked pupil response was substantially diminished (at least 60%) over the duration of the experiment. We account for the variance of fatigue effects in our pupillometry data using multiple common statistical modeling approaches (e.g., linear mixed-effects models of peak, mean, and baseline pupil diameters, as well as growth curve models of time-course data). We conclude that pupil attenuation is a predictable phenomenon that should be accommodated in our experimental designs and statistical models.

Quality Evaluation of Modern Code Reviews Through Intelligent Biometric Program Comprehension

Code review is an essential practice in software engineering to spot code defects in the early stages of software development. Modern code reviews (e.g., acceptance or rejection of pull requests with Git) have become less formal than classic Fagan's inspections, lightweight, and more reliant on individuals (i.e., reviewers). However, reviewers may encounter mentally demanding challenges during the code review, such as code comprehension difficulties or distractions that might affect the code review quality. This work proposes a novel approach that evaluates the quality of code reviews in terms of bug-finding effectiveness and provides the reviewers with a clear message of whether the review should be repeated, indicating the code regions that may not have been well-reviewed. The proposed approach utilizes biometric information collected from the reviewer during the review process using non-intrusive biofeedback devices (e.g., smartwatches). Biometric measures such as Heart Rate Variability (HRV) and task-evoked pupillary response are captured as a surrogate of the cognitive state of the reviewer (e.g., mental workload) and inexpensive desktop eye-trackers compatible with the software development settings. This work uses Artificial Intelligence techniques to predict the cognitive load from the extracted biomarkers and classify each code region according to a set of features. The final evaluation considers various factors such as code complexity, time of the code review, the experience level of the reviewer, and other factors. Our experimental results show the approach could predict the review quality with 87.77%±4.65 accuracy and a Spearman correlation coefficient of 0.85 (p-value < 0.001) between the predicted and the actual review performance. This evaluation validates the cognitive load measurement using electroencephalography (EEG) signals as ground truth for the HRV and pupil signals.

Task-evoked pupillary responses track precision-weighted prediction errors and learning rate during interceptive visuomotor actions

In this study, we examined the relationship between physiological encoding of surprise and the learning of anticipatory eye movements. Active inference portrays perception and action as interconnected inference processes, driven by the imperative to minimise the surprise of sensory observations. To examine this characterisation of oculomotor learning during a hand–eye coordination task, we tested whether anticipatory eye movements were updated in accordance with Bayesian principles and whether trial-by-trial learning rates tracked pupil dilation as a marker of ‘surprise’. Forty-four participants completed an interception task in immersive virtual reality that required them to hit bouncing balls that had either expected or unexpected bounce profiles. We recorded anticipatory eye movements known to index participants’ beliefs about likely ball bounce trajectories. By fitting a hierarchical Bayesian inference model to the trial-wise trajectories of these predictive eye movements, we were able to estimate each individual’s expectations about bounce trajectories, rates of belief updating, and precision-weighted prediction errors. We found that the task-evoked pupil response tracked prediction errors and learning rates but not beliefs about ball bounciness or environmental volatility. These findings are partially consistent with active inference accounts and shed light on how encoding of surprise may shape the control of action.