A person's emotions and state of mind are apparent in their face and eyes. As a Latin proverb states: 'The face is the portrait of the mind; the eyes, its informers'. This presents a significant challenge for Computer Graphics researchers who generate artificial entities that aim to replicate the movement and appearance of the human eye, which is so important in human-human interactions. This review article provides an overview of the efforts made on tackling this demanding task. As with many topics in computer graphics, a cross-disciplinary approach is required to fully understand the workings of the eye in the transmission of information to the user. We begin with a discussion of the movement of the eyeballs, eyelids and the head from a physiological perspective and how these movements can be modelled, rendered and animated in computer graphics applications. Furthermore, we present recent research from psychology and sociology that seeks to understand higher level behaviours, such as attention and eye gaze, during the expression of emotion or during conversation. We discuss how these findings are synthesized in computer graphics and can be utilized in the domains of Human-Robot Interaction and Human-Computer Interaction for allowing humans to interact with virtual agents and other artificial entities. We conclude with a summary of guidelines for animating the eye and head from the perspective of a character animator.

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A Review of Eye Gaze in Virtual Agents, Social Robotics and HCI: Behaviour Generation, User Interaction and Perception

https://statics.scnu.edu.cn/pics/2016/0317/1458208574957758.pdf

Different topological organization of human brain functional networks with eyes open versus eyes closed

Neural substrates of shared attention as social memory: A hyperscanning functional magnetic resonance imaging study.

Single-unit recordings in monkeys have identified effector-specific regions in posterior parietal cortex (PPC), but functional neuroimaging in the human have yielded controversial results. Here we used on-line repetitive transcranial magnetic stimulation (rTMS) to determine saccade and reach specificity in human PPC. A short train of three TMS pulses (10 Hz, 300 ms) was delivered to superior parieto-occipital cortex (SPOC), a region over the mid-posterior intraparietal sulcus (mIPS), and a site posterior to caudal IPS situated over the angular gyrus (AG) during a brief memory interval while subjects planned either a saccade or reach with the left or right hand. Behavioural measures then were compared to controls without rTMS. Stimulation of mIPS and AG produced similar patterns: increased end point variability for reaches and decreased saccade accuracy for contralateral targets. In contrast, stimulation of SPOC deviated reach end points towards visual fixation, and had no effect on saccades. Contralateral-limb specificity was highest for AG and lowest for SPOC. Visual feedback of the hand negated rTMS-induced disruptions of the reach plan for mIPS and AG, but not SPOC. These results suggest that human SPOC is specialized for encoding retinally peripheral reach goals, whereas more anterior-lateral regions (mIPS and AG) along the IPS possess overlapping maps for saccade and reach planning, and are more closely involved in motor details (i.e., planning the reach vector for a specific hand). Acknowledgments: CIHR, OGS, Canada Research Chair

Specificity of human parietal saccade and reach regions during transcranial magnetic stimulation

Ultra-slow Oscillations in fMRI and Resting-State Connectivity: Neuronal and Vascular Contributions and Technical Confounds

It remains unknown why we generate spontaneous eyeblinks every few seconds, more often than necessary for ocular lubrication. Because eyeblinks tend to occur at implicit breakpoints while viewing videos, we hypothesized that eyeblinks are actively involved in the release of attention. We show that while viewing videos, cortical activity momentarily decreases in the dorsal attention network after blink onset but increases in the default-mode network implicated in internal processing. In contrast, physical blackouts of the video do not elicit such reciprocal changes in brain networks. The results suggest that eyeblinks are actively involved in the process of attentional disengagement during a cognitive behavior by momentarily activating the default-mode network while deactivating the dorsal attention network.

https://www.pnas.org/content/pnas/early/2012/12/19/1214804110.full.pdf

Blink-related momentary activation of the default mode network while viewing videos

Our brains represent the position of a visual stimulus egocentrically, in either retinal or craniotopic coordinates. In addition, recent behavioral studies have shown that the stimulus position is automatically represented allocentrically relative to a large frame in the background. Here, we investigated neural correlates of the ‘background coordinate’ using an fMRI adaptation technique. A red dot was presented at different locations on a screen, in combination with a rectangular frame that was also presented at different locations, while the participants looked at a fixation cross. When the red dot was presented repeatedly at the same location relative to the rectangular frame, the fMRI signals significantly decreased in the right precuneus. No adaptation was observed after repeated presentations relative to a small, but salient, landmark. These results suggest that the background coordinate is implemented in the right precuneus.

Yusuke Morito

Papers

Blink-related momentary activation of the default mode network while viewing videos

Automatic representation of a visual stimulus relative to a background in the right precuneus.