Version and vergence eye movements in optokinetic nystagmus induced by optic flow

Implicit weight bias: shared neural substrates for overweight and angry facial expressions revealed by cross-adaptation

The perception of facial expression plays a crucial role in social communication, and it is known to be influenced by various facial cues. Previous studies have reported both positive and negative biases toward overweight individuals. It is unclear whether facial cues, such as facial weight, bias facial expression perception. Combining psychophysics and event-related potential technology, the current study adopted a cross-adaptation paradigm to examine this issue. The psychophysical results of Experiments 1A and 1B revealed a bidirectional cross-adaptation effect between overweight and angry faces. Adapting to overweight faces decreased the likelihood of perceiving ambiguous emotional expressions as angry compared to adapting to normal-weight faces. Likewise, exposure to angry faces subsequently caused normal-weight faces to appear thinner. These findings were corroborated by bidirectional event-related potential results, showing that adaptation to overweight faces relative to normal-weight faces modulated the event-related potential responses of emotionally ambiguous facial expression (Experiment 2A); vice versa, adaptation to angry faces relative to neutral faces modulated the event-related potential responses of ambiguous faces in facial weight (Experiment 2B). Our study provides direct evidence associating overweight faces with facial expression, suggesting at least partly common neural substrates for the perception of overweight and angry faces.

Spatiotopic updating across saccades in the absence of awareness

Despite the continuously changing visual inputs caused by eye movements, our perceptual representation of the visual world remains remarkably stable. Visual stability has been a major area of interest within the field of visual neuroscience. The early visual cortical areas are retinotopic-organized, and presumably there is a retinotopic to spatiotopic transformation process that supports the stable representation of the visual world. In this study, we used a cross-saccadic adaptation paradigm to show that both the orientation adaptation and face gender adaptation could still be observed at the same spatiotopic (but different retinotopic) locations even when the adapting stimuli were rendered invisible. These results suggest that awareness of a visual object is not required for its transformation from the retinotopic to the spatiotopic reference frame.

Investigation of visually induced motion sickness in dynamic 3D contents based on subjective judgment, heart rate variability, and depth gaze behavior

Visually induced motion sickness (VIMS) is an important safety issue in stereoscopic 3D technology. Accompanying subjective judgment of VIMS with objective measurement is useful to identify not only biomedical effects of dynamic 3D contents, but also provoking scenes that induce VIMS, duration of VIMS, and user behavior during VIMS. Heart rate variability and depth gaze behavior are appropriate physiological indicators for such objective observation. However, there is no information about relationship between subjective judgment of VIMS, heart rate variability, and depth gaze behavior. In this paper, we present a novel investigation of VIMS based on simulator sickness questionnaire (SSQ), electrocardiography (ECG), and 3D gaze tracking. Statistical analysis on SSQ data shows that nausea and disorientation symptoms increase as amount of dynamic motions increases (nausea: p<;0.005; disorientation: p<;0.05). To reduce VIMS, SSQ and ECG data suggest that user should perform voluntary gaze fixation at one point when experiencing vertical motion (up or down) and horizontal motion (turn left and right) in dynamic 3D contents. Observation of 3D gaze tracking data reveals that users who experienced VIMS tended to have unstable depth gaze than ones who did not experience VIMS.

Unseen Affective Faces Influence Person Perception Judgments in Schizophrenia

To demonstrate the influence of unconscious affective processing on consciously processed information among people with and without schizophrenia, we used a continuous flash suppression (CFS) paradigm to examine whether early and rapid processing of affective information influences first impressions of structurally neutral faces. People with and without schizophrenia rated visible neutral faces as more or less trustworthy, warm, and competent when paired with unseen smiling or scowling faces compared to when paired with unseen neutral faces. Yet, people with schizophrenia also exhibited a deficit in explicit affect perception. These findings indicate that early processing of affective information is intact in schizophrenia but the integration of this information with semantic contexts is problematic. Furthermore, people with schizophrenia who were more influenced by smiling faces presented outside awareness reported experiencing more anticipatory pleasure, suggesting that the ability to rapidly process affective information is important for anticipation of future pleasurable events.

Enhanced attention amplifies face adaptation

Perceptual adaptation not only produces striking perceptual aftereffects, but also enhances coding efficiency and discrimination by calibrating coding mechanisms to prevailing inputs. Attention to simple stimuli increases adaptation, potentially enhancing its functional benefits. Here we show that attention also increases adaptation to faces. In Experiment 1, face identity aftereffects increased when attention to adapting faces was increased using a change detection task. In Experiment 2, figural (distortion) face aftereffects increased when attention was increased using a snap game (detecting immediate repeats) during adaptation. Both were large effects. Contributions of low-level adaptation were reduced using free viewing (both experiments) and a size change between adapt and test faces (Experiment 2). We suggest that attention may enhance adaptation throughout the entire cortical visual pathway, with functional benefits well beyond the immediate advantages of selective processing of potentially important stimuli. These results highlight the potential to facilitate adaptive updating of face-coding mechanisms by strategic deployment of attentional resources.

Vergence nystagmus induced by motion in the ground plane: normal response characteristics

We displayed backward/forward motion on a computer monitor in the ground plane. Subjects looked at the center of a moving pattern and eye movements of both eyes were recorded with a search coil system. Involuntary nystagmus including vertical version (VV) and horizontal vergence (HV) was recorded. Dynamics of the nystagmus showed that the slow and quick phase of VV and HV were always associated with each other while the monocular horizontal eye movements composed of HV were either symmetrical or asymmetrical. Peak velocity, amplitudes and frequency of the VV and HV responses were quantified. The results suggest that involuntary HV nystagmus can be induced by simple motion from simulated optic flow in the ground plane and the HV nystagmus helps moving subjects to stabilize their gazes on the object of interest.