scholarly journals Ocular fixations modulate audiovisual semantic congruency when standing in an upright position

2021 ◽  
Vol 28 (1) ◽  
Author(s):  
Guillermo Rodríguez-Martínez ◽  
◽  
Henry Castillo-Parra ◽  
Pedro J. Rosa ◽  
◽  
...  
Keyword(s):  
Visual Information ◽  
Body Position ◽  
Upright Position ◽  
Body Posture ◽  
Auditory Stimuli ◽  
Gravity Vector ◽  
Eye Tracker ◽  
Bottom Up ◽  
Semantic Congruency ◽  
Eye Fixations

Introduction: Multisensory audiovisual semantic congruency is the process by which visual information is perceived as integrated to auditory stimuli, because both coincide in terms of simultaneity and semantic correspondence. This study was aimed at establishing whether visual percepts, which semantically correspond to auditory stimuli, are associated with ocular fixations in modulating bottom-up areas while keeping a body posture alignment between the up-direction and the idiotropic axes, as well as in another orientation corresponding to a vectorial opposition between the up-direction and the head idiotropic axis. Method: Two groups (one for each position) were selected from a sample of 88 people. A bistable image was presented on a screen of a fixed 120 Hz eye-tracker device, providing background auditory stimuli so as to establish semantic congruencies and their relations to ocular fixations. Results: It was found that audiovisual semantic congruency is associated with fixations when idiotropic vectors are aligned with the up direction. Fixations manifested in bottom-up modulating areas are not associated with multisensory audiovisual semantic congruency when the head idiotropic vector is parallel with the gravity vector. Eye fixations decrease significantly if the head idiotropic axis is aligned with the gravity vector. Conclusion: It is concluded that body position can affect visual perceptual processes involved in the occurrence of semantic congruency.

scholarly journals Sitting in Judgment: How Body Posture Influences Deception Detection and Gazing Behavior

2021 ◽  
Vol 11 (6) ◽  
pp. 85
Author(s):  
Mircea Zloteanu ◽  
Eva G. Krumhuber ◽  
Daniel C. Richardson
Keyword(s):  
Facial Expressions ◽  
Nonverbal Behavior ◽  
Visual Information ◽  
Deception Detection ◽  
Body Posture ◽  
Additive Effect ◽  
Eye Tracker ◽  
High Stakes ◽  
Body Postures ◽  
Trait Empathy

Body postures can affect how we process and attend to information. Here, a novel effect of adopting an open or closed posture on the ability to detect deception was investigated. It was hypothesized that the posture adopted by judges would affect their social acuity, resulting in differences in the detection of nonverbal behavior (i.e., microexpression recognition) and the discrimination of deceptive and truthful statements. In Study 1, adopting an open posture produced higher accuracy for detecting naturalistic lies, but no difference was observed in the recognition of brief facial expressions as compared to adopting a closed posture; trait empathy was found to have an additive effect on posture, with more empathic judges having higher deception detection scores. In Study 2, with the use of an eye-tracker, posture effects on gazing behavior when judging both low-stakes and high-stakes lies were measured. Sitting in an open posture reduced judges’ average dwell times looking at senders, and in particular, the amount and length of time they focused on their hands. The findings suggest that simply shifting posture can impact judges’ attention to visual information and veracity judgments (Mg = 0.40, 95% CI (0.03, 0.78)).

scholarly journals Selection of visual information for lightness judgements by eye movements

2013 ◽  
Vol 368 (1628) ◽  
pp. 20130056 ◽  
Author(s):  
Matteo Toscani ◽  
Matteo Valsecchi ◽  
Karl R. Gegenfurtner
Keyword(s):  
Eye Movements ◽  
Visual System ◽  
Visual Information ◽  
Selection Process ◽  
Sampling Strategy ◽  
Selection Strategy ◽  
Eye Fixations ◽  
Target Layer ◽  
Highly Correlated ◽  
Selection Of

When judging the lightness of objects, the visual system has to take into account many factors such as shading, scene geometry, occlusions or transparency. The problem then is to estimate global lightness based on a number of local samples that differ in luminance. Here, we show that eye fixations play a prominent role in this selection process. We explored a special case of transparency for which the visual system separates surface reflectance from interfering conditions to generate a layered image representation. Eye movements were recorded while the observers matched the lightness of the layered stimulus. We found that observers did focus their fixations on the target layer, and this sampling strategy affected their lightness perception. The effect of image segmentation on perceived lightness was highly correlated with the fixation strategy and was strongly affected when we manipulated it using a gaze-contingent display. Finally, we disrupted the segmentation process showing that it causally drives the selection strategy. Selection through eye fixations can so serve as a simple heuristic to estimate the target reflectance.

scholarly journals Refixation control in free viewing: a specialized mechanism divulged by eye-movement-related brain activity

2018 ◽  
Vol 120 (5) ◽  
pp. 2311-2324 ◽  
Author(s):  
Andrey R. Nikolaev ◽  
Radha Nila Meghanathan ◽  
Cees van Leeuwen
Keyword(s):  
Eye Movement ◽  
Visual Information ◽  
Direct Evidence ◽  
Search Task ◽  
Visual Search Task ◽  
Brain Activity ◽  
Movement Control ◽  
Planning Stage ◽  
Eye Fixations ◽  
Free Viewing

In free viewing, the eyes return to previously visited locations rather frequently, even though the attentional and memory-related processes controlling eye-movement show a strong antirefixation bias. To overcome this bias, a special refixation triggering mechanism may have to be recruited. We probed the neural evidence for such a mechanism by combining eye tracking with EEG recording. A distinctive signal associated with refixation planning was observed in the EEG during the presaccadic interval: the presaccadic potential was reduced in amplitude before a refixation compared with normal fixations. The result offers direct evidence for a special refixation mechanism that operates in the saccade planning stage of eye movement control. Once the eyes have landed on the revisited location, acquisition of visual information proceeds indistinguishably from ordinary fixations. NEW & NOTEWORTHY A substantial proportion of eye fixations in human natural viewing behavior are revisits of recently visited locations, i.e., refixations. Our recently developed methods enabled us to study refixations in a free viewing visual search task, using combined eye movement and EEG recording. We identified in the EEG a distinctive refixation-related signal, signifying a control mechanism specific to refixations as opposed to ordinary eye fixations.

scholarly journals Ambisonics Sound Source Localization With Varying Amount of Visual Information in Virtual Reality

2021 ◽  
Vol 2 ◽  
Author(s):  
Thirsa Huisman ◽  
Axel Ahrens ◽  
Ewen MacDonald
Keyword(s):  
Virtual Reality ◽  
Visual Information ◽  
Right Hemisphere ◽  
Sound Field ◽  
Auditory Stimuli ◽  
Spatial Cues ◽  
Sound Sources ◽  
Acoustic Localization ◽  
Localization Performance ◽  
The Right

To reproduce realistic audio-visual scenarios in the laboratory, Ambisonics is often used to reproduce a sound field over loudspeakers and virtual reality (VR) glasses are used to present visual information. Both technologies have been shown to be suitable for research. However, the combination of both technologies, Ambisonics and VR glasses, might affect the spatial cues for auditory localization and thus, the localization percept. Here, we investigated how VR glasses affect the localization of virtual sound sources on the horizontal plane produced using either 1st-, 3rd-, 5th- or 11th-order Ambisonics with and without visual information. Results showed that with 1st-order Ambisonics the localization error is larger than with the higher orders, while the differences across the higher orders were small. The physical presence of the VR glasses without visual information increased the perceived lateralization of the auditory stimuli by on average about 2°, especially in the right hemisphere. Presenting visual information about the environment and potential sound sources did reduce this HMD-induced shift, however it could not fully compensate for it. While the localization performance itself was affected by the Ambisonics order, there was no interaction between the Ambisonics order and the effect of the HMD. Thus, the presence of VR glasses can alter acoustic localization when using Ambisonics sound reproduction, but visual information can compensate for most of the effects. As such, most use cases for VR will be unaffected by these shifts in the perceived location of the auditory stimuli.

Impact of body posture change on peripherally inserted central catheter tip position in Chinese cancer patients

2020 ◽  
Vol 21 (5) ◽  
pp. 732-737
Author(s):  
Chunli Liu ◽  
Dingbiao Jiang ◽  
Tao Jin ◽  
Chuanyin Chen ◽  
Ruchun Shi ◽  
...  
Keyword(s):  
Upright Position ◽  
Body Posture ◽  
Peripherally Inserted Central Catheter ◽  
Central Catheter ◽  
Posture Change ◽  
Body Change ◽  
Catheter Tip ◽  
The Mean ◽  
Tip Position ◽  
Chinese Cancer Patients

Purpose: To evaluate the influence of body posture change on the peripherally inserted central catheter tip position in Chinese cancer patients. Methods: A prospective observational trial was conducted in a tertiary cancer hospital from August to September 2018. After the insertion of peripherally inserted central catheter, chest X-ray films were taken to check the catheter tip in the upright and supine positions, respectively. The distance from the carina to the catheter tip was separately measured on both chest films by nurses. The primary study outcome was the distance and direction of the catheter tip movement. The secondary study outcome was to analyze the influence factors on the catheter tip movement. The third study outcome was to observe the related adverse events caused by the catheter tip movement. Results: A total of 79 patients were included, the results showed that 61 moved cephalad, 14 moved caudally, and 4 did not move with body change from the supine to the upright position. When moved cephalad, the mean distance was 19.34 ± 11.95 mm; when moved caudally, the mean distance was –15.83 ± 8.97 mm. The difference between the two positions was statistically significant ( p < 0.001). There was also a statistically significant difference between catheter tip movement direction and body mass index ( p = 0.009) and height ( p = 0.015). Two patients developed arrhythmias; no cardiac tamponade was found due to body posture change. Conclusion: The results of this work implied that the tips of the catheter tend to shift toward the cephalad with body change from the supine to the upright position. A study involving a larger sample size is needed to find more information in the future.

Neural substrates of visual percepts, imagery, and hallucinations

2002 ◽  
Vol 25 (2) ◽  
pp. 194-195
Author(s):  
Stephen Grossberg
Keyword(s):  
Visual Attention ◽  
Normal Control ◽  
Mental Imagery ◽  
Visual Information ◽  
Neural Substrates ◽  
Visual Hallucinations ◽  
Neural Models ◽  
Top Down ◽  
Bottom Up

Recent neural models clarify many properties of mental imagery as part of the process whereby bottom-up visual information is influenced by top-down expectations, and how these expectations control visual attention. Volitional signals can transform modulatory top-down signals into supra-threshold imagery. Visual hallucinations can occur when the normal control of these volitional signals is lost.

Top-Down versus Bottom-up Control of Saccades in Texture Perception

Perception ◽  
1997 ◽  
Vol 26 (1_suppl) ◽  
pp. 162-162 ◽  
Author(s):  
R Groner ◽  
A von Mühlenen ◽  
M Groner
Keyword(s):  
Eye Movements ◽  
Spatial Frequency ◽  
Target Stimulus ◽  
Saccadic Eye Movements ◽  
Landing Site ◽  
Luminance Contrast ◽  
Eye Tracker ◽  
Top Down ◽  
Bottom Up ◽  
Low Pass

An experiment was conducted to examine the influence of luminance, contrast, and spatial frequency content on saccadic eye movements. 112 pictures of natural textures from Brodatz were low-pass filtered (0.04 – 0.76 cycles deg−1) and high-pass filtered (1.91 – 19.56 cycles deg−1) and varied in luminance (low and high) and contrast (low and high), resulting in eight images per texture. Circular clippings of the central parts of the images (approximately 15% of the whole image) were used as stimuli. In the condition of bottom - up processing, the eight stimuli derived from one texture were presented for 1500 ms in a circular arrangement around the fixation cross. They were followed by a briefly presented target stimulus in the centre, which in half the trials was identical to one of the eight test stimuli. Participants had to decide whether the target stimulus was identical to any of the preceding stimuli. During a trial, their eye movements were recorded by means of a Dual-Purkinje-Image eye tracker. In the top - down condition, the target stimulus was presented in each trial prior to the display of the test stimulus. It was assumed that the priming with a target produced a top - down processing of the test stimuli. The latency and landing site of the first saccade were computed and compared between the top - down and bottom - up conditions. It is hypothesised that stimulus characteristics (luminance, contrast, and spatial frequency) play a more prominent role in bottom - up processing, while top - down processing is adjusted to the particular characteristics of the prime.

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