Pupils say more than a thousand words: Pupil size reflects how observed actions are interpreted

Quesque, François; Behrens, Friederike; Kret, Mariska E.

doi:10.1016/j.cognition.2019.04.016

Cited by 8 publications

(5 citation statements)

References 67 publications

(100 reference statements)

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“…For instance, exploring a cooperative motor task, Quesque and Coello 38 reported that the spatial amplification of a grasp-to-place motor action was broader, resulting in a higher arm trajectory, when the partner's eye-level was set at a higher position. This result is in line with the key role of the gaze in the process of action understanding in social contexts [39][40][41][42][43] . Because of their social value, the spatio-temporal variations of object-directed motor actions are also thought to serve as crucial cues for an observer to identify the agent's social goal [44][45][46] .…”

Section: The Combined Effects Of Motor and Social Goals On The Kinemasupporting

confidence: 85%

The combined effects of motor and social goals on the kinematics of object-directed motor action

Gigliotti

Sampaio

Bartolo

et al. 2020

Sci Rep

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Voluntary actions towards manipulable objects are usually performed with a particular motor goal (i.e., a task-specific object-target-effector interaction) and in a particular social context (i.e., who would benefit from these actions), but the mutual influence of these two constraints has not yet been properly studied. For this purpose, we asked participants to grasp an object and place it on either a small or large target in relation to Fitts’ law (motor goal). This first action prepared them for a second grasp-to-place action which was performed under temporal constraints, either by the participants themselves or by a confederate (social goal). Kinematic analysis of the first preparatory grasp-to-place action showed that, while deceleration time was impacted by the motor goal, peak velocity was influenced by the social goal. Movement duration and trajectory height were modulated by both goals, the effect of the social goal being attenuated by the effect of the motor goal. Overall, these results suggest that both motor and social constraints influence the characteristics of object-oriented actions, with effects that combine in a hierarchical way.

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Section: The Combined Effects Of Motor and Social Goals On The Kinemasupporting

confidence: 85%

The combined effects of motor and social goals on the kinematics of object-directed motor action

Gigliotti

Sampaio

Bartolo

et al. 2020

Sci Rep

View full text Add to dashboard Cite

show abstract

“…In addition to reflecting inner states, changes in pupil size appear to have a social signalling function (Quesque et al, 2019 ) and can be considered a form of basic communication between conspecifics (Kret et al, 2014 ). Investigating the social value of changes in pupil size, Hess ( 1975 ) established that women with larger pupils were described by men as “more feminine,” “prettier,” and “softer” compared to women with small pupils (Hess, 1975 ).…”

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confidence: 99%

Attention Towards Pupil Size in Humans and Bonobos (Pan paniscus)

2022

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Previous work has established that humans have an attentional bias towards emotional signals, and there is some evidence that this phenomenon is shared with bonobos, our closest relatives. Although many emotional signals are explicit and overt, implicit cues such as pupil size also contain emotional information for observers. Pupil size can impact social judgment and foster trust and social support, and is automatically mimicked, suggesting a communicative role. While an attentional bias towards more obvious emotional expressions has been shown, it is unclear whether this also extends to a more subtle implicit cue, like changes in pupil size. Therefore, the current study investigated whether attention is biased towards pupils of differing sizes in humans and bonobos. A total of 150 human participants (141 female), with a mean age of 19.13 (ranging from 18 to 32 years old), completed an online dot-probe task. Four female bonobos (6 to 17 years old) completed the dot-probe task presented via a touch screen. We used linear mixed multilevel models to examine the effect of pupil size on reaction times. In humans, our analysis showed a small but significant attentional bias towards dilated pupils compared to intermediate-sized pupils and intermediate-sized pupils when compared to small pupils. Our analysis did not show a significant effect in bonobos. These results suggest that the attentional bias towards emotions in humans can be extended to a subtle unconsciously produced signal, namely changes in pupil size. Due to methodological differences between the two experiments, more research is needed before drawing a conclusion regarding bonobos.

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“…A number of applications to our findings are conceivable for applications in research and technology, be it in understanding interpersonal communication ( Einhäuser et al., 2010 ; Naber, Stoll, Einhäuser, & Carter, 2013 ; Quesque, Behrens, & Kret, 2019) or in allowing innovative human–computer interfaces ( Strauch, Ehlers, & Huckauf, 2017) .…”

Section: Discussionmentioning

confidence: 88%

Decoding binary decisions under differential target probabilities from pupil dilation: A random forest approach

et al. 2021

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Although our pupils slightly dilate when we look at an intended target, they do not when we look at irrelevant distractors. This finding suggests that it may be possible to decode the intention of an observer, understood as the outcome of implicit covert binary decisions, from the pupillary dynamics over time. However, few previous works have investigated the feasibility of this approach and the few that did, did not control for possible confounds such as motor-execution, changes in brightness, or target and distractor probability. We report on our efforts to decode intentions from pupil dilation obtained under strict experimental control on a single trial basis using a machine learning approach. The basis for our analyses are data of 69 participants who looked at letters that needed to be selected with stimulus probabilities that varied systematically in a blockwise manner (n = 19,417 trials). We confirm earlier findings that pupil dilation is indicative of intentions and show that these can be decoded with a classification performance of up to 76% area under the curve for receiver operating characteristic curves if targets are rarer than distractors. To better understand which characteristics of the pupillary signal are most informative, we finally compare relative feature importances. The first derivative of pupil size changes was found to be most relevant, allowing us to decode intention within only about 800 ms of trial onset. Taken together, our results provide credible insights into the potential of decoding intentions from pupil dilation and may soon form the basis for new applications in visual search, gaze-based interaction, or human-robot interaction.

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Pupils say more than a thousand words: Pupil size reflects how observed actions are interpreted

Cited by 8 publications

References 67 publications

The combined effects of motor and social goals on the kinematics of object-directed motor action

The combined effects of motor and social goals on the kinematics of object-directed motor action

Attention Towards Pupil Size in Humans and Bonobos (Pan paniscus)

Decoding binary decisions under differential target probabilities from pupil dilation: A random forest approach

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