scholarly journals The evolutionary origins of primate scleral coloration

2021 ◽  
Author(s):  
Alex S. Mearing ◽  
Judith M. Burkart ◽  
Jacob Dunn ◽  
Sally E. Street ◽  
Kathelijne Koops
Keyword(s):  
Generalized Least Squares ◽  
Gaze Direction ◽  
Primate Species ◽  
Gaze Following ◽  
Social Environments ◽  
The Gaze ◽  
Evolutionary Origins ◽  
Competitive Environments ◽  
Lethal Aggression ◽  
Cooperative Behaviors

Primate gaze following behaviors are of great interest to evolutionary scientists studying social cognition. The ability of an organism to determine a conspecifics likely intentions from their gaze direction may confer an advantage to individuals in a social group. This advantage could be cooperative and/or competitive. Humans are unusual in possessing depigmented sclerae whereas most other extant primates, including the closely related chimpanzee, possess dark scleral pigment. The origins of divergent scleral morphologies are currently unclear, though human white sclerae are often assumed to underlie our hyper-cooperative behaviors. Here, we use phylogenetic generalized least squares (PGLS) analyses with previously generated species-level scores of proactive prosociality, social tolerance (both n=15 primate species), and conspecific lethal aggression (n=108 primate species) to provide the first quantitative, comparative test of three complementary hypotheses. The cooperative eye and self-domestication explanations predict white sclerae to be associated with cooperative, rather than competitive, environments. The gaze camouflage hypothesis predicts that dark scleral pigment functions as gaze direction camouflage in competitive social environments. We show that white sclerae in primates are associated with increased cooperative behaviors whereas dark sclerae are associated with reduced cooperative behaviors and increased intra-specific lethal aggression. Our results lend support to all three hypotheses of scleral evolution, suggesting that primate scleral morphologies evolve in relation to variation in social environment.

Can infants use robot gaze for object learning?

2013 ◽  
Vol 14 (3) ◽  
pp. 351-365 ◽  
Author(s):  
Yuko Okumura ◽  
Yasuhiro Kanakogi ◽  
Takayuki Kanda ◽  
Hiroshi Ishiguro ◽  
Shoji Itakura
Keyword(s):  
Cognitive Development ◽  
Humanoid Robot ◽  
Gaze Direction ◽  
Gaze Following ◽  
Gaze Behavior ◽  
The Gaze ◽  
Object Learning ◽  
Verbal Signal ◽  
Infant Learning

Previous research has shown that although infants follow the gaze direction of robots, robot gaze does not facilitate infants’ learning for objects. The present study examined whether robot gaze affects infants’ object learning when the gaze behavior was accompanied by verbalizations. Twelve-month-old infants were shown videos in which a robot with accompanying verbalizations gazed at an object. The results showed that infants not only followed the robot’s gaze direction but also preferentially attended to the cued object when the ostensive verbal signal was present. Moreover, infants showed enhanced processing of the cued object when ostensive and referential verbal signals were increasingly present. These effects were not observed when mere nonverbal sound stimuli instead of verbalizations were added. Taken together, our findings indicate that robot gaze accompanying verbalizations facilitates infants’ object learning, suggesting that verbalizations are important in the design of robot agents from which infants can learn. Keywords: gaze following; humanoid robot; infant learning; verbalization; cognitive development

scholarly journals Decoding of the other’s focus of attention by a temporal cortex module

2019 ◽  
Author(s):  
H. Ramezanpour ◽  
P. Thier
Keyword(s):  
Social Context ◽  
Social Interactions ◽  
Temporal Cortex ◽  
Neural Mechanism ◽  
Focus Of Attention ◽  
The Other ◽  
Gaze Direction ◽  
Gaze Following ◽  
The Gaze ◽  
Flexible Linkage

AbstractFaces attract the observer’s attention towards objects and locations of interest for the other, thereby allowing the two agents to establish joint attention. Previous work has delineated a network of cortical “patches” in the macaque cortex, processing faces, eventually also extracting information on the other’s gaze direction. Yet, the neural mechanism that links information on gaze direction, guiding the observer’s attention to the relevant object has remained elusive. Here we present electrophysiological evidence for the existence of a distinct “gaze-following patch (GFP)” with neurons that establish this linkage in a highly flexible manner. The other’s gaze and the object, singled out by the gaze, are linked only if this linkage is pertinent within the prevailing social context. The properties of these neurons establish the GFP as a key switch in controlling social interactions based on the other’s gaze.One Sentence SummaryNeurons in a “gaze-following patch” in the posterior temporal cortex orchestrate the flexible linkage between the other’s gaze and objects of interest to both, the other and the observer.

scholarly journals Decoding of the other’s focus of attention by a temporal cortex module

2020 ◽  
Vol 117 (5) ◽  
pp. 2663-2670 ◽  
Author(s):  
Hamidreza Ramezanpour ◽  
Peter Thier
Keyword(s):  
Social Context ◽  
Social Interactions ◽  
Joint Attention ◽  
Temporal Cortex ◽  
Neural Mechanism ◽  
Focus Of Attention ◽  
The Other ◽  
Gaze Direction ◽  
Gaze Following ◽  
The Gaze

Faces attract the observer’s attention toward objects and locations of interest for the other, thereby allowing the two agents to establish joint attention. Previous work has delineated a network of cortical “patches” in the macaque cortex, processing faces, eventually also extracting information on the other’s gaze direction. Yet, the neural mechanism that links information on gaze direction, guiding the observer’s attention to the relevant object, has remained elusive. Here we present electrophysiological evidence for the existence of a distinct “gaze-following patch” (GFP) with neurons that establish this linkage in a highly flexible manner. The other’s gaze and the object, singled out by the gaze, are linked only if this linkage is pertinent within the prevailing social context. The properties of these neurons establish the GFP as a key switch in controlling social interactions based on the other’s gaze.

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 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.

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