Biology subjects

Chapman, C. S.

Publications and source records attributed to Chapman, C. S..

6 recordsLinked to original sources

bioRxiv2023

Continuous Measures of Decision-Difficulty Captured Remotely: I. Mouse-tracking sensitivity extends to tablets and smartphones

As decisions require actions to have an effect on the world, measures derived from movements such as using a mouse to control a cursor on a screen provide powerful and dynamic indices of decision-making. In this first of a set of two studies, we replicated classic reach-decision paradigms across computers, tablets, and smartphones, we show that portable touch-devices can sensitively capture decision-difficulty. We see this in pre- and during-movement temporal and motoric measures across diverse decision domains. We found touchscreen interactions to more sensitively reflect decision-difficulty during movement compared to computer interactions, and the latter to be more sensitive before movement initiation. Paired with additional evidence for the flexibility and unique utility of pre- and during-movement measures, this substantiates the use of widely available touch-devices to massively extend the reach of decision science. We build upon this in the second study in this series (Bertrand et al., 2023) with the use of webcam eye-tracking to further elucidate, earlier in time, the decision process. This subsequent work provides additional support for tools that enable remote collection of rich decision data in ecologically-valid environments.

neuroscience↗

bioRxiv2023

Continuous Measures of Decision-Difficulty Captured Remotely: II. Webcam eye-tracking reveals early decision processing

As decisions require the gathering of relevant information, eye-tracking measures that capture the way visual information is typically acquired offer powerful indices of the dynamic decision-making process. This study is the second of a pair of studies that explore continuous measures of decision-making using remote, online tools in naturalistic settings. While cursor-tracking, used in the companion paper (Ouellette Zuk et al., 2023), enabled access to dynamic decision processes expressed during movement, in the present study, we now employ webcam eye-tracking to examine the dynamics of information gathering during decision making prior to movement initiation. Using three previously published binary choice tasks, we explored indices of decision difficulty in the gaze dynamics that would complement the motor measures in our companion paper. We find that harder choices elicit more eye dwells and longer final dwells, reflecting a decision resolution process that Ouellette Zuk et al. index during the final choice movement. Beyond this, we identify distinct gaze patterns uniquely employed in each task, revealing the utility and sensitivity of gaze metrics in illuminating the early difficulty-independent information gathering processes at play. Together, this paper series demonstrates the power of remote, online methods as tools for deeply understanding the complete, dynamic and continuous decision process, from the first glance to the final response.

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bioRxiv2021

Generating accurate 3D gaze vectors using synchronized eye tracking and motion capture

Assessing gaze behaviour during real-world tasks is difficult; dynamic bodies moving through dynamic worlds make gaze analysis difficult. Current approaches involve laborious coding of pupil positions. In settings where motion capture and mobile eye tracking are used concurrently in naturalistic tasks, it is critical that data collection be simple, efficient, and systematic. One solution is to combine eye tracking with motion capture to generate 3D gaze vectors. When combined with tracked or known object locations, 3D gaze vector generation can be automated. Here we use combined eye and motion capture and explore how linear regression models generate accurate 3D gaze vectors. We compare spatial accuracy of models derived from four short calibration routines across three pupil data inputs: the efficacy of calibration routines were assessed, a validation task requiring short fixations on taskrelevant locations, and a naturalistic object interaction task to bridge the gap between laboratory and "in the wild" studies. Further, we generated and compared models using spherical and cartesian coordinate systems and monocular (Left or Right) or binocular data. All calibration routines performed similarly, with the best performance (i.e., sub-centimetre errors) coming from the naturalistic task trials when the participant is looking at an object in front of them. We found that spherical coordinate systems generate the most accurate gaze vectors with no differences in accuracy when using monocular or binocular data. Overall, we recommend one-minute calibration routines using binocular pupil data combined with a spherical world coordinate system to produce the highest quality gaze vectors.

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bioRxiv2020

Reaching for known unknowns: Rapid reach decisions accurately reflect the future state of dynamic probabilistic information

Everyday tasks such as catching a ball appear effortless, but in fact require complex interactions and tight temporal coordination between the brains visual and motor systems. What makes such interceptive actions particularly impressive is the capacity of the brain to account for temporal delays in the central nervous system--a limitation that can be mitigated by making predictions about the environment as well as ones own actions. Here, we wanted to assess how well human participants can plan an upcoming movement based on a dynamic, predictable stimulus that is not the target of action. A central stationary or rotating stimulus determined the probability that each of two potential targets would be the eventual target of a rapid reach-to-touch movement. We examined the extent to which reach movement trajectories convey internal predictions about the future state of dynamic probabilistic information conveyed by the rotating stimulus. We show that movement trajectories reflect the target probabilities determined at movement onset, suggesting that humans rapidly and accurately integrate visuospatial predictions and estimates of their own reaction times to effectively guide action.

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bioRxiv2019

Gaze and Movement Assessment (GaMA): Inter-site validation of a visuomotor upper limb functional protocol

BackgroundSuccessful hand-object interactions require precise hand-eye coordination with continual movement adjustments. Quantitative measurement of this visuomotor behaviour could provide valuable insight into upper limb impairments. The Gaze and Movement Assessment (GaMA) was developed to provide protocols for simultaneous motion capture and eye tracking during the administration of two functional tasks, along with data analysis methods to generate standard measures of visuomotor behaviour. The objective of this study was to investigate the reproducibility of the GaMA protocol across two independent groups of non-disabled participants, with different raters using different motion capture and eye tracking technology.\n\nMethodsTwenty non-disabled adults performed the Pasta Box Task and the Cup Transfer Task. Upper body and eye movements were recorded using motion capture and eye tracking, respectively. Measures of hand movement, angular joint kinematics, and eye gaze were compared to those from a different sample of twenty non-disabled adults who had previously performed the same protocol with different technology, rater and site.\n\nResultsParticipants took longer to perform the tasks versus those from the earlier study, although the relative time of each movement phase was similar. Measures that were dissimilar between the groups included hand distances travelled, hand trajectories, number of movement units, eye latencies, and peak angular velocities. Similarities included all hand velocity and grip aperture measures, eye fixations, and most peak joint angle and range of motion measures.\n\nDiscussionThe reproducibility of GaMA was confirmed by this study, despite a few differences introduced by learning effects, task demonstration variation, and limitations of the kinematic model. The findings from this study provide confidence in the reliability of normative results obtained by GaMA, indicating it accurately quantifies the typical behaviours of a non-disabled population. This work advances the consideration for use of GaMA in populations with upper limb sensorimotor impairment.

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bioRxiv2017

Entrainment of theta, not alpha, oscillations is predictive of the brightness enhancement of a flickering stimulus

Frequency-dependent brightness enhancement, where a flickering light can appear twice as bright as an equiluminant constant light, has been reported to exist within the alpha (8 - 12 Hz) band. Could oscillatory neural activity be driving this perceptual effect? Here, in two experiments, human subjects reported which of two flickering stimuli were brighter. Strikingly, 4 Hz stimuli were reported as brighter more than 80% of the time when compared to all other tested frequencies, even though all stimuli were equiluminant and of equal temporal length. Electroencephalography recordings showed that inter-trial phase coherence (ITC) of theta (4 Hz) was: 1) Significantly greater than alpha, contralateral to the flickering stimulus; 2) Enhanced by the presence of a second ipsilateral 4 Hz flickering stimulus; and 3) Uniquely lateralized, unlike the alpha band. Importantly, on trials with two identical stimuli (i.e. 4 Hz vs 4 Hz), the brightness discrimination judgment could be predicted by the hemispheric balance in the amount of 4 Hz ITC. We speculate that the theta rhythm plays a distinct information transfer role, where its ability to share information between hemispheres via entrainment promotes a better processing of visual information to inform a discrimination decision.

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