scholarly journals Fear-specific leftward bias in gaze direction judgment

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Yue Zhang ◽  
Qiqi Hu ◽  
Xinwei Lai ◽  
Zhonghua Hu ◽  
Shan Gao
Keyword(s):  
Judgment Task ◽  
Gaze Direction ◽  
Emotional Information ◽  
Cerebral Lateralization ◽  
Low Level ◽  
The Gaze ◽  
Fearful Faces ◽  
Perception Bias ◽  
Behavioural Experiments ◽  
Direction Judgment

AbstractPrevious studies have shown that humans have a left spatial attention bias in cognition and behaviour. However, whether there exists a leftward perception bias of gaze direction has not been investigated. To address this gap, we conducted three behavioural experiments using a forced-choice gaze direction judgment task. The point of subjective equality (PSE) was employed to measure whether there was a leftward perception bias of gaze direction, and if there was, whether this bias was modulated by face emotion. The results of experiment 1 showed that the PSE of fearful faces was significantly positive as compared to zero and this effect was not found in angry, happy, and neutral faces, indicating that participants were more likely to judge the gaze direction of fearful faces as directed to their left-side space, namely a leftward perception bias. With the response keys counterbalanced between participants, experiment 2a replicated the findings in experiment 1. To further investigate whether the gaze direction perception variation was contributed by emotional or low-level features of faces, experiment 2b and 3 used inverted faces and inverted eyes, respectively. The results revealed similar leftward perception biases of gaze direction in all types of faces, indicating that gaze direction perception was biased by emotional information in faces rather than low-level facial features. Overall, our study demonstrates that there a fear-specific leftward perception bias in processing gaze direction. These findings shed new light on the cerebral lateralization in humans.

scholarly journals Have the eyes of bioluminescent scale worms adapted to see their own light? A comparative study of eyes and vision in Harmothoe imbricata and Lepidonotus squamatus

2021 ◽  
Author(s):  
A. Garm ◽  
S. H. Simonsen ◽  
P. Mendoza-González ◽  
K. Worsaae
Keyword(s):  
Comparative Study ◽  
Temporal Resolution ◽  
North Atlantic ◽  
Gaze Direction ◽  
The Gaze ◽  
Eye Morphology ◽  
The North ◽  
Peak Sensitivity ◽  
The North Atlantic ◽  
Behavioural Experiments

Annelids constitute a diverse phylum with more than 19000 species, exhibiting greatly varying morphologies and lifestyles ranging from sessile detritivores to fast swimming active predators. The lifestyle of an animal is closely linked to its sensory systems not least the visual equipment. Interestingly, many errant annelid species from different families such as the scale worms, Polynoidae, share the same two pairs of eyes on their prostomium. These eyes are typically 100-200 µm in diameter and structurally similar judged from the gross morphology. The polynoids, Harmothoe imbricata and Lepidonotus squamatus from the North Atlantic are both benthic predators preying on small invertebrates but only H. imbricata can produce bioluminescence in their scales. Here we have examined their eye morphology, photoreceptor physiology, and light guided behaviour in order to assess their visual capacity and visual ecology. Whereas the structure and physiology of the two pairs of eyes are remarkably similar within species, the only difference being the gaze direction, the photoreceptor physiology differs between the two species. Both species express a single opsin in their eyes but in H. imbricata the peak sensitivity is green shifted and the temporal resolution is lower, suggesting that the eyes of H. imbricata are adapted to detect their own bioluminescence. The behavioural experiments showed that both species are strictly night active but yielded no support to the hypothesis that H. imbricata are repelled by their own bioluminescence.

scholarly journals What is unique about the human eye? Comparative image analysis on the external eye morphology of human and nonhuman great apes

2021 ◽  
Author(s):  
Fumihiro Kano ◽  
Takeshi Furuichi ◽  
Chie Hashimoto ◽  
Christopher Krupenye ◽  
Jesse G Leinwand ◽  
...  
Keyword(s):  
Image Analysis ◽  
Eye Gaze ◽  
Great Apes ◽  
Gaze Direction ◽  
Human Eye ◽  
The Gaze ◽  
Eye Morphology ◽  
New Findings ◽  
Heated Debate ◽  
Signaling Hypothesis

The gaze-signaling hypothesis and the related cooperative-eye hypothesis posit that humans have evolved special external eye morphology, including exposed white sclera (the white of the eye), to enhance the visibility of eye-gaze direction and thereby facilitate conspecific communication through joint-attentional interaction and ostensive communication. However, recent quantitative studies questioned these hypotheses based on new findings that humans are not necessarily unique in certain eye features compared to other great ape species. Therefore, there is currently a heated debate on whether external eye features of humans are distinguished from those of other apes and how such distinguished features contribute to the visibility of eye-gaze direction. This study leveraged updated image analysis techniques to test the uniqueness of human eye features in facial images of great apes. Although many eye features were similar between humans and other species, a key difference was that humans have uniformly white sclera which creates clear visibility of both eye outline and iris; the two essential features contributing to the visibility of eye-gaze direction. We then tested the robustness of the visibility of these features against visual noises such as darkening and distancing and found that both eye features remain detectable in the human eye, while eye outline becomes barely detectable in other species under these visually challenging conditions. Overall, we identified that humans have distinguished external eye morphology among other great apes, which ensures robustness of eye-gaze signal against various visual conditions. Our results support and also critically update the central premises of the gaze-signaling hypothesis.

Effects of Gaze Direction in Vision and Audition

Perception ◽  
1997 ◽  
Vol 26 (1_suppl) ◽  
pp. 137-137
Author(s):  
W H Ehrenstein ◽  
J Lewald ◽  
L Schlykowa
Keyword(s):  
Visual Cues ◽  
Posterior Parietal Cortex ◽  
Reaction Times ◽  
Visual Sensitivity ◽  
Gaze Direction ◽  
The Gaze ◽  
Visual Shift ◽  
Stimulus Speed ◽  
Posterior Parietal ◽  
Visual Reference

We asked to what extent the respective gaze direction influences (i) the spatial congruence of perceived direction of auditory and visual cues, and (ii) the discrimination of the direction of target motion. With fixed head position, subjects directed their gaze in various positions and localised auditory targets (band-pass noise, 2 kHz) presented at one of nine positions (straight ahead, or four symmetric positions to the left or right separated by 2.75 deg, respectively). Forced-choice judgements, whether the sound was perceived to the left or right of a visual reference light, show that the azimuth of the sound was perceived as slightly shifted to the left of a visual reference when the gaze was directed to the left, and vice versa. The maximum of this relative auditory - visual shift was 4.7 deg over a range of 45 deg (left or right) of gaze directions. In (ii), a spot of light started at the centre of a monitor and moved at 2 or 12 deg s−1 leftward or rightward. Subjects reported the direction by pressing a key; their gaze was directed at 0, 8, or 16 deg to the left or right. Mean choice-reaction times increased with increasing gaze eccentricity, but differently depending on stimulus direction and speed: with left fixation they were shorter for leftward than rightward motion; with right fixation they were shorter for rightward motion. This effect was stronger for the slow than for the fast stimulus speed. Thus, facilitation occurs when stimuli move with moderate velocity toward the direction of gaze. While the auditory-visual shift in (i) may reflect an incomplete transformation of spatial (craniocentric and oculocentric) coordinates as suggested by recordings in the primate midbrain, the results in (ii) conform with reports of specialised units in the posterior parietal cortex (areas LIP, 7a, MST) that, in registering oculomotor position, modulate visual sensitivity.

scholarly journals A naturalistic paradigm simulating gaze-based social interactions for the investigation of social agency

2019 ◽  
Vol 52 (3) ◽  
pp. 1044-1055
Author(s):  
Marie-Luise Brandi ◽  
Daniela Kaifel ◽  
Juha M. Lahnakoski ◽  
Leonhard Schilbach
Keyword(s):  
Social Interaction ◽  
Social Interactions ◽  
Ecological Validity ◽  
The Other ◽  
Behavioral Data ◽  
Gaze Direction ◽  
Social Agency ◽  
Gaze Behavior ◽  
The Gaze ◽  
Real Person

Abstract Sense of agency describes the experience of being the cause of one’s own actions and the resulting effects. In a social interaction, one’s actions may also have a perceivable effect on the actions of others. In this article, we refer to the experience of being responsible for the behavior of others as social agency, which has important implications for the success or failure of social interactions. Gaze-contingent eyetracking paradigms provide a useful tool to analyze social agency in an experimentally controlled manner, but the current methods are lacking in terms of their ecological validity. We applied this technique in a novel task using video stimuli of real gaze behavior to simulate a gaze-based social interaction. This enabled us to create the impression of a live interaction with another person while being able to manipulate the gaze contingency and congruency shown by the simulated interaction partner in a continuous manner. Behavioral data demonstrated that participants believed they were interacting with a real person and that systematic changes in the responsiveness of the simulated partner modulated the experience of social agency. More specifically, gaze contingency (temporal relatedness) and gaze congruency (gaze direction relative to the participant’s gaze) influenced the explicit sense of being responsible for the behavior of the other. In general, our study introduces a new naturalistic task to simulate gaze-based social interactions and demonstrates that it is suitable to studying the explicit experience of social agency.

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