Task-evoked Pupillary Responses Research Articles

Pupillometry provides a psychophysiological index of arousal level and cognitive effort during the performance of a visual-auditory dual-task in individuals with a history of concussion

Research shows that concussions cause long-term deficits in executive functions when tested using challenging tasks with high cognitive load. The neurophysiological mechanism(s) associated with executive dysfunction are not well understood. Pupillometry provides a non-invasive index of arousal and cognitive load; therefore, the current study investigated whether pupillometry could help explain the persistent deficits in dual-task performance in individuals with a history of concussion (n = 14) compared to controls (n = 13). Participants were tested using a computerized Corsi block task which increased in difficulty as a function of set size (i.e., number of blocks to be remembered) and task condition (i.e., performed alone and concurrently with an auditory task). Pupil size was measured during the initial fixation prior to the Corsi task to assess arousal level, and during the encoding phase to assess task evoked pupil response. Results showed that: 1) in contrast to the control group, pupil size was not modulated by task condition in the concussed group indicating that arousal level was similar in the single and dual task; 2) task evoked pupil dilation increased as a function of set size in the single task in both groups, 3) in contrast to the control group, those with a history of concussion had similar pupil size during the single and dual task conditions. One interpretation of these results is that individuals with a history of concussion exert greater effort when performing relatively easier tasks, and they reach capacity limits when the cognitive load is lower in comparison to non-concussed individuals. In conclusion, pupillometry may provide insight into persisting deficits in executive functions following concussion(s).

Disentangling listening effort and memory load beyond behavioural evidence: Pupillary response to listening effort during a concurrent memory task.

Recent research has demonstrated that pupillometry is a robust measure for quantifying listening effort. However, pupillary responses in listening situations where multiple cognitive functions are engaged and sustained over a period of time remain hard to interpret. This limits our conceptualisation and understanding of listening effort in realistic situations, because rarely in everyday life are people challenged by one task at a time. Therefore, the purpose of this experiment was to reveal the dynamics of listening effort in a sustained listening condition using a word repeat and recall task. Words were presented in quiet and speech-shaped noise at different signal-to-noise ratios (SNR): 0dB, 7dB, 14dB and quiet. Participants were presented with lists of 10 words, and required to repeat each word after its presentation. At the end of the list, participants either recalled as many words as possible or moved on to the next list. Simultaneously, their pupil dilation was recorded throughout the whole experiment. When only word repeating was required, peak pupil dilation (PPD) was bigger in 0dB versus other conditions; whereas when recall was required, PPD showed no difference among SNR levels and PPD in 0dB was smaller than repeat-only condition. Baseline pupil diameter and PPD followed different variation patterns across the 10 serial positions within a block for conditions requiring recall: baseline pupil diameter built up progressively and plateaued in the later positions (but shot up when listeners were recalling the previously heard words from memory); PPD decreased at a pace quicker than in repeat-only condition. The current findings demonstrate that additional cognitive load during a speech intelligibility task could disturb the well-established relation between pupillary response and listening effort. Both the magnitude and temporal pattern of task-evoked pupillary response differ greatly in complex listening conditions, urging for more listening effort studies in complex and realistic listening situations.

Pupillary Responses for Cognitive Load Measurement to Classify Difficulty Levels in an Educational Video Game: Empirical Study.

BackgroundA learning task recurrently perceived as easy (or hard) may cause poor learning results. Gamer data such as errors, attempts, or time to finish a challenge are widely used to estimate the perceived difficulty level. In other contexts, pupillometry is widely used to measure cognitive load (mental effort); hence, this may describe the perceived task difficulty.ObjectiveThis study aims to assess the use of task-evoked pupillary responses to measure the cognitive load measure for describing the difficulty levels in a video game. In addition, it proposes an image filter to better estimate baseline pupil size and to reduce the screen luminescence effect.MethodsWe conducted an experiment that compares the baseline estimated from our filter against that estimated from common approaches. Then, a classifier with different pupil features was used to classify the difficulty of a data set containing information from students playing a video game for practicing math fractions.ResultsWe observed that the proposed filter better estimates a baseline. Mauchly’s test of sphericity indicated that the assumption of sphericity had been violated (χ214=0.05; P=.001); therefore, a Greenhouse-Geisser correction was used (ε=0.47). There was a significant difference in mean pupil diameter change (MPDC) estimated from different baseline images with the scramble filter (F5,78=30.965; P<.001). Moreover, according to the Wilcoxon signed rank test, pupillary response features that better describe the difficulty level were MPDC (z=−2.15; P=.03) and peak dilation (z=−3.58; P<.001). A random forest classifier for easy and hard levels of difficulty showed an accuracy of 75% when the gamer data were used, but the accuracy increased to 87.5% when pupillary measurements were included.ConclusionsThe screen luminescence effect on pupil size is reduced with a scrambled filter on the background video game image. Finally, pupillary response data can improve classifier accuracy for the perceived difficulty of levels in educational video games.

Effect of Speech-to-Noise Ratio and Luminance on a Range of Current and Potential Pupil Response Measures to Assess Listening Effort.

In hearing research, pupillometry is an established method of studying listening effort. The focus of this study was to evaluate several pupil measures extracted from the Task-Evoked Pupil Responses (TEPRs) in speech-in-noise test. A range of analysis approaches was applied to extract these pupil measures, namely (a) pupil peak dilation (PPD); (b) mean pupil dilation (MPD); (c) index of pupillary activity; (d) growth curve analysis (GCA); and (e) principal component analysis (PCA). The effect of signal-to-noise ratio (SNR; Data Set A: –20 dB, –10 dB, +5 dB SNR) and luminance (Data Set B: 0.1 cd/m2, 360 cd/m2) on the TEPRs were investigated. Data Sets A and B were recorded during a speech-in-noise test and included TEPRs from 33 and 27 normal-hearing native Dutch speakers, respectively. The main results were as follows: (a) A significant effect of SNR was revealed for all pupil measures extracted in the time domain (PPD, MPD, GCA, PCA); (b) Two time series analysis approaches (GCA, PCA) provided modeled temporal profiles of TEPRs (GCA); and time windows spanning subtasks performed in a speech-in-noise test (PCA); and (c) All pupil measures revealed a significant effect of luminance. In conclusion, multiple pupil measures showed similar effects of SNR, suggesting that effort may be reflected in multiple aspects of TEPR. Moreover, a direct analysis of the pupil time course seems to provide a more holistic view of TEPRs, yet further research is needed to understand and interpret its measures. Further research is also required to find pupil measures less sensitive to changes in luminance.

Task-evoked pupillary responses track effort exertion: Evidence from task-switching.

A spate of research has examined how individuals regulate effortful processing in service of goal-directed behaviors. One key challenge in developing an account of this regulation is quantifying the momentary amount of cognitive effort exerted by an individual in service of their goals. A growing body of literature has suggested using task-evoked pupil dilations as a potential psychophysiological index of cognitive effort; however, it remains unclear whether pupil diameter indexes effort exertion or merely reflects task load, as both are tightly intertwined. Here, we attempt to disentangle these disparate accounts of pupil diameter by leveraging individual differences in executive function (as measured by Stroop interference) and a motivational manipulation (i.e., monetary incentives) while participants complete a task-switching paradigm. In line with both the effort and demand accounts, we observed larger task-evoked pupillary responses (TEPRs) for trials in which there was a task switch versus a task repetition. Additionally, we found that larger phasic pupillary responses at baseline (without reward incentives) predicted smaller switch costs. Mirroring this pattern, individual differences in reward-induced switch cost reductions were predicted by reward-induced increases in phasic pupil diameter. Finally, we observed that the interrelationship between effort and pupil diameter at baseline was modulated by individual differences in Stroop interference costs. Together, these findings provide support for an effort account of TEPRs, and suggest that pupillometry is a viable index of cognitive effort.

Effortful listening under the microscope: Examining relations between pupillometric and subjective markers of effort and tiredness from listening.

Effort during listening is commonly measured using the task-evoked pupil response (TEPR); a pupillometric marker of physiological arousal. However, studies to date report no association between TEPR and perceived effort. One possible reason for this is the way in which self-report effort measures are typically administered, namely as a single data point collected at the end of a testing session. Another possible reason is that TEPR might relate more closely to the experience of tiredness from listening than to effort per se. To examine these possibilities, we conducted two preregistered experiments that recorded subjective ratings of effort and tiredness from listening at multiple time points and examined their covariance with TEPR over the course of listening tasks varying in levels of acoustic and attentional demand. In both experiments, we showed a within-subject association between TEPR and tiredness from listening, but no association between TEPR and effort. The data also suggest that the effect of task difficulty on the experience of tiredness from listening may go undetected using the traditional approach of collecting a single data point at the end of a listening block. Finally, this study demonstrates the utility of a novel correlation analysis technique ("rmcorr"), which can be used to overcome statistical power constraints commonly found in the literature. Teasing apart the subjective and physiological mechanisms that underpin effortful listening is a crucial step toward addressing these difficulties in older and/or hearing-impaired individuals.

Contrast Is in the Eye of the Beholder: Infelicitous Beat Gesture Increases Cognitive Load During Online Spoken Discourse Comprehension.

We investigated how two cues to contrast-beat gesture and contrastive pitch accenting-affect comprehenders' cognitive load during processing of spoken referring expressions. In two visual-world experiments, we orthogonally manipulated the presence of these cues and their felicity, or fit, with the local (sentence-level) referential context in critical referring expressions while comprehenders' task-evoked pupillary responses (TEPRs) were examined. In Experiment 1, beat gesture and contrastive accenting always matched the referential context of filler referring expressions and were therefore relatively felicitous on the global (experiment) level, whereas in Experiment 2, beat gesture and contrastive accenting never fit the referential context of filler referring expressions and were therefore infelicitous on the global level. The results revealed that both beat gesture and contrastive accenting increased comprehenders' cognitive load. For beat gesture, this increase in cognitive load was driven by both local and global infelicity. For contrastive accenting, this increase in cognitive load was unaffected when cues were globally felicitous but exacerbated when cues were globally infelicitous. Together, these results suggest that comprehenders' cognitive resources are taxed by processing infelicitous use of beat gesture and contrastive accenting to convey contrast on both the local and global levels.

Binocular Vision, Visual Function, and Pupil Dynamics in People Living With Dementia and Their Relation to the Rate of Cognitive Decline and Structural Changes Within the Brain: Protocol for an Observational Study.

BackgroundVisual impairment is a common comorbidity in people living with dementia. Addressing sources of visual difficulties can have a significant impact on the quality of life for people living with dementia and their caregivers. Depth perception problems are purportedly common in dementia and also contribute to falls, visuomotor task difficulties, and poorer psychosocial well-being. However, depth perception and binocular vision are rarely assessed in dementia research. Sleep fragmentation is also common for people living with dementia, and binocular cooperation for depth perception can be affected by fatigue. Pupillary responses under cognitive load also have the potential to be a risk marker for cognitive decline in people living with dementia and can be combined with the above measures for a comprehensive evaluation of clinical visual changes in people living with dementia and their relation to changes in cognitive status, sleep quality, and cortical structure or function.ObjectiveThis study aims to characterize the nature of clinical visual changes and altered task-evoked pupillary responses that may occur in people living with dementia and evaluate whether these responses relate to changes in cognitive status (standardized Mini Mental State Examination [MMSE] score), Pittsburgh sleep quality index, and cortical structure or function.MethodsThis proposed exploratory observational study will enroll ≤210 people with recently diagnosed dementia (within the last 24 months). The following parameters will be assessed on 3 occasions, 4 months apart (plus or minus 2 weeks): visual function (visual acuity and contrast sensitivity), binocular function (motor fusion and stereopsis), task-evoked pupillary responses (minimum and maximum pupil size, time to maximum dilation, and dilation velocity), cognitive status (MMSE score), and sleep quality (Pittsburgh Sleep Quality Index). A subset of patients (n=30) with Alzheimer disease will undergo structural and functional magnetic resonance imaging at first and third visits, completing a 10-day consensus sleep diary to monitor sleep quality, verified by sleep actimetry.ResultsThis research was funded in February 2018 and received National Health Service Research Ethics Committee approval in September 2018. The data collection period was from October 1, 2018, to November 30, 2019. A total of 24 participants were recruited for the study. The data analysis is complete, with results expected to be published before the end of 2020.ConclusionsFindings will demonstrate how often people with dementia experience binocular vision problems. If frequent, diagnosing and treating them could improve quality of life by reducing the risk of falls and fine visuomotor task impairment and by relieving psychosocial anxiety. This research will also demonstrate whether changes in depth perception, pupillary responses, and quality of vision relate to changes in memory or sleep quality and brain structure or function. If related, these quick and noninvasive eye tests help monitor dementia. This would help justify whether binocular vision and pupillary response testing should be included in dementia-friendly eye-testing guidelines.International Registered Report Identifier (IRRID)RR1-10.2196/16089

Pupillary and behavioral markers of alerting and orienting: An individual difference approach

Measuring task-evoked pupillary (TEP) responses as an index of phasic activity in the locus coeruleus (LC), we examined two competing hypotheses regarding the alerting and orienting mechanisms of attention. According to a dual mechanism account (Fernandez-Duque & Posner, 1997), two separate noradrenergic and cholinergic mechanisms modulate, respectively, the alerting and orienting effects. However, Corbetta and colleagues (2008) proposed that LC phasic activity may also be involved in orienting effect through its functional relationship with the ventral attentional network. We recruited seventy-five healthy Norwegian participants to perform a Posner cueing task. Both behavioral and pupillary responses revealed the alerting effect. Also, both behavioral and pupillary responses indicated that cued attention is affected by age. Behavioral responses also revealed orienting effect However, we found no TEP differences between valid, invalid, and neutral conditions, suggesting that TEP effects were driven by the alerting effect of cue presentation. Moreover, both behavioral and pupillary estimates of alertness and orienting were uncorrelated. Finally, individual differences in general cognitive abilities did not appear to affect the orienting and alerting mechanisms. This pattern of results is consistent with the dual mechanism account of attention. However, the LC involvement in the (re)orienting attention may be driven by state-specific factors.

Pupillary Responses Indicate Working Memory Processing Differences: Implications For Healthy And Clinical Populations

Task-evoked pupillary responses (PR) are established psychophysiological measures for neural resource allocation. During working memory tasks, pupils dilate proportional to increasing cognitive demands and constrict when demands exceed resource availability. PRs have demonstrated greater sensitivity to load-dependent processing differences in clinical populations, beyond performance accuracy, under high cognitive demands. Few studies have examined concussion history, sex, and performance accuracy effects on PRs across varying cognitive load levels. PURPOSE: To examine effects of concussion history, sex, and performance accuracy on PR in healthy individuals during a digit-span task. METHODS: Participants self-reported sex (female vs. male) and concussion history (yes vs. no), and completed a backwards digit-span task in a single testing session. A virtual reality headset with 60Hz infrared eye tracking displayed the task and recorded pupil size fluctuations. Pupil size (diameter in mm) was recorded before each trial (baseline=3sec) and following randomly presented digit sequences between 4 and 14 digits long (retention=2sec). PR was calculated as the mean size during retention, normalized to mean baseline. Accuracy was calculated as the proportion of correctly recalled digits by serial position. A mixed effects model examined concussion history, sex, and accuracy effects on PR across sequence-lengths (a priori α=0.05). RESULTS: 40 participants were included [age=21.9±2.1years; males=50%; 17 (43%) with concussion history]. There were significant effects of sex (F1,36=15.66, p<0.001) and accuracy (F1,2588=4.70, p<0.03) on overall relative PR controlling for all other model predictors and interactions. Specifically, females exhibited smaller mean PRs compared to males. Smaller mean PRs were also associated with higher average task accuracy. CONCLUSION: In our study, females exhibited smaller overall pupillary responses during a digit-span working memory task compared to males, indicating potential sex-dependent processing differences. The association between better task accuracy and smaller PRs may further support PR meauress to better inform neurocognitive processing differences in healthy and clinical populations, when demands exceed cognitive resource availability.

Uncharacteristic Task-Evoked Pupillary Responses Implicate Atypical Locus Ceruleus Activity in Autism.

Autism spectrum disorder (ASD) is characterized partly by atypical attentional engagement, reflected in exaggerated and variable responses to sensory stimuli. Attentional engagement is known to be regulated by the locus ceruleus (LC). Moderate baseline LC activity globally dampens neural responsivity and is associated with adaptive deployment and narrowing of attention to task-relevant stimuli. In contrast, increased baseline LC activity enhances neural responsivity across cortex and widening of attention to environmental stimuli regardless of their task relevance. Given attentional atypicalities in ASD, this study is the first to evaluate whether, under different attentional task demands, individuals with ASD exhibit a different profile of LC activity compared with typically developing controls. Males and females with ASD and age- and gender-matched controls participated in a one-back letter detection test while task-evoked pupillary responses, an established correlate for LC activity, were recorded. Participants completed this task in two conditions, either in the absence or presence of distractor auditory tones. Compared with controls, individuals with ASD evinced atypical pupillary responses in the presence versus absence of distractors. Notably, this atypical pupillary profile was evident despite the fact that both groups exhibited equivalent task performance. Moreover, between-group differences in pupillary responses were observed specifically in response to task-relevant events, providing confirmation that the group differences most likely were specifically associated with distinctions in LC activity. These findings suggest that individuals with ASD show atypical modulation of LC activity with changes in attentional demands, offering a possible mechanistic and neurobiological account for attentional atypicalities in ASD.SIGNIFICANCE STATEMENT Individuals with autism spectrum disorder (ASD) exhibit atypical attentional behaviors, including altered sensory responses and atypical fixedness, but the neural mechanism underlying these behaviors remains elusive. One candidate mechanism is atypical locus ceruleus (LC) activity, as the LC plays a critical role in attentional modulation. Specifically, LC activity is involved in regulating the trade-off between environmental exploration and focused attention. This study shows that, under tightly controlled conditions, task-evoked pupil responses, an LC activity proxy, are lower in individuals with ASD than in controls, but only in the presence of task-irrelevant stimuli. This suggests that individuals with ASD evince atypical modulation of LC activity in accordance with changes in attentional demands, offering a mechanistic account for attentional atypicalities in ASD.

MP47-12 CORRELATING SIMULATOR AND LIVE ROBOTIC SURGICAL PERFORMANCE USING BIOMETRICS, SIMULATOR METRICS AND AUTOMATED PERFORMANCE METRICS

You have accessJournal of UrologySurgical Technology & Simulation: Training & Skills Assessment II (MP47)1 Apr 2020MP47-12 CORRELATING SIMULATOR AND LIVE ROBOTIC SURGICAL PERFORMANCE USING BIOMETRICS, SIMULATOR METRICS AND AUTOMATED PERFORMANCE METRICS Andrew Cowan*, Runzhuo Ma, Jessica Nguyen, Swetha Rajkumar, Samuel Mingo, Ryan Hakim, Sandra Marshall, and Andrew Hung Andrew Cowan*Andrew Cowan* More articles by this author , Runzhuo MaRunzhuo Ma More articles by this author , Jessica NguyenJessica Nguyen More articles by this author , Swetha RajkumarSwetha Rajkumar More articles by this author , Samuel MingoSamuel Mingo More articles by this author , Ryan HakimRyan Hakim More articles by this author , Sandra MarshallSandra Marshall More articles by this author , and Andrew HungAndrew Hung More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000000902.012AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: Multiple training modalities exist for robotic surgery, each with their own performance metrics. This study compares performance in analogous vesicourethral anastomosis (VUA) training tasks in simulation (SIM) and dry lab (DL). We investigated recorded biometrics, SIM metrics, and DL Automated Performance Metrics (APMs) to determine which were capable of distinguishing experts (E) from novices (N). METHODS: Experts (≥ 300 cases) and novices (<300 cases) performed VUAs during SIM and DL sessions (Figure 1). 22 SIM metrics (kinematics, safety) were captured by the simulator. 20 DL APMs (kinematics, events) were recorded by a systems data recorder (Intuitive Surgical). In both settings, task-evoked pupillary response (reported as Index of Cognitive Activity [ICA]) and heart rate variability (HRV) were collected as cognitive workload and stress biometrics respectively, analyzed by EyeWorks Cognitive Workload Software and Kubios HRV. Pearson Correlation, Mann-Whitney and Independent t-tests were used for the comparative analyses. RESULTS: Our study included 6 experts (median 1300 [400-3000]) and 11 novices (25 [0-250]). 7/8 metrics directly comparable between SIM and DL showed significant positive correlation (p≤0.032). Of these, kinematic metrics including path lengths of all three instruments (dominant/non-dominant hand, camera) (ρ≥0.677, p≤0.008), and both biometrics (ρ≥0.806, p≤0.001) showed strong correlations. ICA distinguished E v. N across SIM (p=0.036) and DL (p=0.024) while HRV was able in DL (p=0.024). 4/22 SIM metrics distinguished E v. N: task time (p=0.031), clutch usage (p=0.040), unnecessary needle piercings (p=0.026) and suspected injury to endopelvic fascia (p=0.040). This contrasts with 13/20 DL APMs (p≤0.038) including: linear velocities of all three instruments (p≤0.038) and dominant-hand instrument wrist articulation (p=0.013). Novices experienced higher cognitive workload in DL (p=0.024) and SIM (p=0.036), while all participants experienced higher cognitive workload in SIM than DL (p<0.001). CONCLUSIONS: A majority of performance metrics between SIM and DL exhibited a moderate to strong correlation. APMs on the live robot, focused on kinematics, are better able to distinguish E v. N surgical ability than error-focused SIM metrics. Source of Funding: This study was funded in part by an Intuitive Surgical Clinical Grant; Intuitive Surgical provided the systems data recorder. Research reported in this publication was supported in part by the National Institute Of Biomedical Imaging And Bioengineering of the National Institutes of Health under Award Number K23EB026493. © 2020 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 203Issue Supplement 4April 2020Page: e688-e689 Advertisement Copyright & Permissions© 2020 by American Urological Association Education and Research, Inc.MetricsAuthor Information Andrew Cowan* More articles by this author Runzhuo Ma More articles by this author Jessica Nguyen More articles by this author Swetha Rajkumar More articles by this author Samuel Mingo More articles by this author Ryan Hakim More articles by this author Sandra Marshall More articles by this author Andrew Hung More articles by this author Expand All Advertisement PDF downloadLoading ...

Task-evoked pupil response for accurately recognized accented speech.

Unfamiliar second-language (L2) accents present a common challenge to speech understanding. However, the extent to which accurately recognized unfamiliar L2-accented speech imposes a greater cognitive load than native speech remains unclear. The current study used pupillometry to assess cognitive load for native English listeners during the perception of intelligible Mandarin Chinese-accented English and American-accented English. Results showed greater pupil response (indicating greater cognitive load) for the unfamiliar L2-accented speech. These findings indicate that the mismatches between unfamiliar L2-accented speech and native listeners' linguistic representations impose greater cognitive load even when recognition accuracy is at ceiling.

Pupillary dilation responses as a midlife indicator of risk for Alzheimer's disease: association with Alzheimer's disease polygenic risk

Locus coeruleus (LC) tau accumulation begins early. Targeting LC (dys)function might improve early identification for Alzheimer's disease (AD) risk. Pupillary responses during cognitive tasks are driven by the LC and index cognitive effort. Despite equivalent task performance, adults with mild cognitive impairment have greater pupil dilation/effort during digit span than cognitively normal (CN) individuals. We hypothesized that AD polygenic risk scores (AD-PRSs) would be associated with pupillary responses in middle-aged CN adults. Pupillary responses during digit span tasks were heritable (h2 = 0.30–0.36) in 1119 men aged 56–66 years. In a CN subset—all with comparable span capacities (n = 539)—higher AD-PRSs were associated with greater pupil dilation/effort in a high (9-digit) cognitive load condition (Cohen's d = 0.36 for upper vs. lower quartile of AD-PRS distribution). Results held up after controlling for APOE genotype. Results support pupillary response—and by inference, LC dysfunction—as a genetically mediated biomarker of early mild cognitive impairment/AD risk. In combination with other biomarkers, task-evoked pupillary responses may provide additional information for early screening of genetically at-risk individuals even before cognitive declines.

Applying linear additive models to isolate component processes in task-evoked pupil responses

Applying linear additive models to isolate component processes in task-evoked pupil responses

Using objective robotic automated performance metrics and task-evoked pupillary response to distinguish surgeon expertise.

In this study, we investigate the ability of automated performance metrics (APMs) and task-evoked pupillary response (TEPR), as objective measures of surgeon performance, to distinguish varying levels of surgeon expertise during generic robotic surgical tasks. Additionally, we evaluate the association between APMs and TEPR. Participants completed ten tasks on a da Vinci Xi Surgical System (Intuitive Surgical, Inc.), each representing a surgical skill type: EndoWrist® manipulation, needle targeting, suturing/knot tying, and excision/dissection. Automated performance metrics (instrument motion tracking, EndoWrist® articulation, and system events data) and TEPR were recorded by a systems data recorder (Intuitive Surgical, Inc.) and Tobii Pro Glasses 2 (Tobii Technologies, Inc.), respectively. The Kruskal-Wallis test determined significant differences between groups of varying expertise. Spearman's rank correlation coefficient measured associations between APMs and TEPR. Twenty-six participants were stratified by robotic surgical experience: novice (no prior experience; n = 9), intermediate (< 100 cases; n = 9), and experts (≥ 100 cases; n = 8). Several APMs differentiated surgeon experience including task duration (p < 0.01), time active of instruments (p < 0.03), linear velocity of instruments (p < 0.04), and angular velocity of dominant instrument (p < 0.04). Task-evoked pupillary response distinguished surgeon expertise for three out of four task types (p < 0.04). Correlation trends between APMs and TEPR revealed that expert surgeons move more slowly with high cognitive workload (ρ < - 0.60, p < 0.05), while novices move faster under the same cognitive experiences (ρ > 0.66, p < 0.05). Automated performance metrics and TEPR can distinguish surgeon expertise levels during robotic surgical tasks. Furthermore, under high cognitive workload, there can be a divergence in robotic movement profiles between expertise levels.

Pupillary response to light and tasks in early and late onset essential tremor patients

IntroductionLate-onset essential tremor is characterised by shorter life expectancy and more advanced aging parameters and may therefore be an ‘aging-related’ tremor. Brainstem functions involved in pupillary responses are hypothesized to reflect such earlier aging. The pupillary light response (PLR) and a task evoked pupillary response (TEPR) were used to test this hypothesis in same-aged patients with early onset (EOET) and late onset (LOET) essential tremor and healthy controls. Subjects and methodsAge related changes of the PLR and TEPR during the paced auditory serial addition test (PASAT) were tested in 57 normal subjects. Subsequently, 13 patients with LOET and 16 patients with EOET were compared with 15 age matched healthy controls. Standard parameters of PLR were recorded, amongst others the time to maximum acceleration of the PLR (T1) and the time to maximum velocity (T2). The TEPR was determined during the PASAT as the percentage change in pupil size (PCPS). Data were analysed with ANOVA and post-hoc testing. ResultsIn normal subjects the pupil diameter, latency, maximum acceleration/velocity and percentage amplitude were correlated with age. Latency of the pupillary light response was significantly longer in LOET compared to controls and EOET while no differences were found between EOET and controls. The TEPR showed no significant differences between the three groups. ConclusionLOET showed a prolonged latency of the PLR compared to EOET possibly indicating premature aging or rather pathophysiological differences on brainstem level. This study further supports the hypothesis of abnormal aging in LOET.

Speech Planning at Turn Transitions in Dialog Is Associated With Increased Processing Load.

Speech planning is a sophisticated process. In dialog, it regularly starts in overlap with an incoming turn by a conversation partner. We show that planning spoken responses in overlap with incoming turns is associated with higher processing load than planning in silence. In a dialogic experiment, participants took turns with a confederate describing lists of objects. The confederate's utterances (to which participants responded) were pre-recorded and varied in whether they ended in a verb or an object noun and whether this ending was predictable or not. We found that response planning in overlap with sentence-final verbs evokes larger task-evoked pupillary responses, while end predictability had no effect. This finding indicates that planning in overlap leads to higher processing load for next speakers in dialog and that next speakers do not proactively modulate the time course of their response planning based on their predictions of turn endings. The turn-taking system exerts pressure on the language processing system by pushing speakers to plan in overlap despite the ensuing increase in processing load.

Task-Evoked Pupillary Responses in Nursing Simulation as an Indicator of Stress and Cognitive Load

BackgroundThere are no studies identifying specific tasks in a simulation that increase stress and cognitive workload. MethodsThis was a two-group comparative study of Novice and Expert Nurses participating in simulation using pupillometry to measure stress and cognitive load associated with specific tasks. ResultsSignificantly higher stress was found in the Novices for four of the six expected tasks, specifically interventional tasks requiring clinical judgment. ConclusionsThe Novices had greater stress on interventional type tasks. Simulations with more emphasis on interventional tasks in which the nursing student is the sole decider of interventions may decrease stress and enhance performance.

IR-camera-based measurements of 2D/3D cognitive fatigue in 2D/3D display system using task-evoked pupillary response.

This study was carried out to evaluate a method used to measure three-dimensional (3D) cognitive fatigue based on the pupillary response. This technique was designed to overcome measurement burdens by using non-contact methods. The pupillary response is related to cognitive function by a neural pathway and may be an indicator of 3D cognitive fatigue. Twenty-six undergraduate students (including 14 women) watched both 2D and 3D versions of a video for 70min. The participants experienced visual fatigue after viewing the 3D content. Measures such as subjective rating, response time, event-related potential latency, heartbeat-evoked potential (HEP) alpha power, and task-evoked pupillary response (TEPR) latency were significantly different. Multitrait-multimethod matrix analysis indicated that HEP and TEPR latency measures had stronger reliability and higher correlations with 3D cognitive fatigue than other measures. TEPR latency may be useful for quantitatively determining 3D visual fatigue, as it can be easily used to evaluate 3D visual fatigue using a non-contact method without measuring burden.