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result(s) for
"Harada, Yuki"
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Effect of virtual interactions through avatar agents on the joint Simon effect
2025
The joint Simon effect refers to inhibitory responses to spatially competing stimuli during a complementary task. This effect has been considered to be influenced by the social factors of a partner: sharing stimulus-action representation. According to this account, virtual interactions through their avatars would produce the joint Simon effect even when the partner did not physically exist in the same space because the avatars are intentional agents. To investigate this, we conducted two joint experiments in which participants controlled avatars as their agents in immersive virtual environments. In Experiment 1, participants were asked to touch a virtual button through their avatars when a target color of an object was presented. The target position was manipulated to be compatible with the button (compatible stimulus) or incompatible with the button (incompatible stimulus). In Experiment 2, the task was identical to that in Experiment 1 except that participants’ gaze position was either visualized or not during the task. We hypothesized that visualizing the partner’s gaze would enhance the joint Simon effect because gaze is a cue to mentalize others’ internal states. The results showed that avatar-based interactions more significantly delayed responses for the incompatible than for the compatible stimulus. However, inconsistent with our hypothesis, visualizing the partner’s gaze position did not influence responses for spatially competing stimuli. These results suggest that virtual interactions through avatar agents can produce the joint Simon effect even when the partner does not physically exist in the same space.
Journal Article
Does the presence of a friend reduce cardiovascular response to stress even over a screen?
by
Kambara, Ayumi
,
Harada, Yuki
,
Mitsuishi, Hisashi
in
Adult
,
Biology and Life Sciences
,
Blood pressure
2024
Although meeting close friends through video calls has become common, less is known about its stress-buffering effect. This study aims to examine whether cardiovascular responses to stress are decreased when the presence of a friend on a monitor compared to the presence of a friend in person or alone. Forty-six undergraduate students completed a stress task while in the room with a friend (1) in person (in-person condition), (2) on Zoom (online condition), or (3) alone (alone condition). Blood pressure and heart rate were monitored throughout the experiment. Analyses revealed that diastolic blood pressure after the stress was recovered closer to the pre-stress state under in-person and online conditions than alone condition. However, the study observed no differences across groups regarding self-reported affect. In summary, this result suggests that even the online presence of a friend, as well as in-person friends, may help recover blood pressure to the original state without one’s awareness.
Journal Article
Quantitative evaluation of visual guidance effects for 360-degree directions
2022
A head-mounted display cannot cover an angle of visual field as wide as that of natural view (out-of-view problem). To enhance the visual cognition of an immersive environment, previous studies have developed various guidance designs that visualize the location or direction of items presented in the users’ surroundings. However, two issues regarding the guidance effects remain unresolved: How are the guidance effects different with each guided direction? How much is the cognitive load required by the guidance? To investigate the two issues, we performed a visual search task in an immersive environment and measured the search time of a target and time spent to recognize a guidance design. In this task, participants searched for a target presented on a head-mounted display and reported the target color while using a guidance design. The guidance designs (a moving window, 3D arrow, radiation, spherical gradation, and 3D radar) and target directions were manipulated. The search times showed an interaction effect between guidance designs and guided directions, e.g., the 3D arrow and radar shorten the search time for targets presented at the back of users. The recognition times showed that the participants required short times to recognize the details of the moving window and radiation but long times for the 3D arrow, spherical gradation, and 3D radar. These results suggest that the moving window and radiation are effective with respect to cognitive load, but the 3D arrow and radar are effective for guiding users’ attention to necessary items presented at the out-of-view.
Journal Article
Whistler-mode chorus waves at Mars
2023
Chorus waves are naturally occurring electromagnetic emissions in space and are known to produce highly energetic electrons in the hazardous radiation belt. The characteristic feature of chorus is its fast frequency chirping, whose mechanism remains a long-standing problem. While many theories agree on its nonlinear nature, they differ on whether or how the background magnetic field inhomogeneity plays a key role. Here, using observations of chorus at Mars and Earth, we report direct evidence showing that the chorus chirping rate is consistently related to the background magnetic field inhomogeneity, despite orders of magnitude difference in a key parameter quantifying the inhomogeneity at the two planets. Our results show an extreme test of a recently proposed chorus generation model and confirm the connection between the chirping rate and magnetic field inhomogeneity, opening the door to controlled plasma wave excitation in the laboratory and space.
Although whistler-mode chorus waves are common in the Earth’s and other planetary magnetospheres, the mechanism behind fast frequency chirping is debated. Here, the authors show the presence of chorus emissions at Mars, with fundamentally the same nonlinear nature as those at Earth, despite vastly different magnetic and plasma conditions.
Journal Article
Observation of Magnetic Domains in Amorphous Magnetic Wires with a Diameter of 10 μm Used in GSR Sensors
by
Honkura, Shinpei
,
Takezawa, Masaaki
,
Harada, Yuki
in
amorphous wire
,
Communication
,
GSR sensor
2023
The core of a Gigahertz Spin Rotation (GSR) sensor, a compact and highly sensitive magnetic sensor, is composed of Co–Fe-based amorphous magnetic wire with a diameter of 10 μm. Observations of the magnetic domain structure showed that this magnetic wire has unusual magnetic noise characteristics. Bamboo-shaped magnetic domains a few hundred micrometers in width were observed to form inside the wire, and smaller domains a few micrometers across were observed to form inside these larger domains. The magnetic domain pattern changed abruptly when an external magnetic field was applied to the wire. Herein is shown how these changes may be a source of magnetic noise in the wire.
Journal Article
The effect of task-irrelevant spatial contexts on 360-degree attention
2020
The effect of spatial contexts on attention is important for evaluating the risk of human errors and the accessibility of information in different situations. In traditional studies, this effect has been investigated using display-based and non-laboratory procedures. However, these two procedures are inadequate for measuring attention directed toward 360-degree environments and controlling exogeneous stimuli. In order to resolve these limitations, we used a virtual-reality-based procedure and investigated how spatial contexts of 360-degree environments influence attention. In the experiment, 20 students were asked to search for and report a target that was presented at any location in 360-degree virtual spaces as accurately and quickly as possible. Spatial contexts comprised a basic context (a grey and objectless space) and three specific contexts (a square grid floor, a cubic room, and an infinite floor). We found that response times for the task and eye movements were influenced by the spatial context of 360-degree surrounding spaces. In particular, although total viewing times for the contexts did not match the saliency maps, the differences in total viewing times between the basic and specific contexts did resemble the maps. These results suggest that attention comprises basic and context-dependent characteristics, and the latter are influenced by the saliency of 360-degree contexts even when the contexts are irrelevant to a task.
Journal Article
Wing-shaped walls: A directional effect of obstacles on manual avoidance
2024
Visual information can be used to plan, start, and coordinate manual movements in obstacle avoidance. An intriguing example of visuomotor coordination is the effect of wing-shaped walls, in which walls are oriented away from or toward a moving agent. A historical story from medieval Japan recounts that wing-shaped walls disrupted the agent's movement more when oriented toward the agent than when oriented away from the agent. This study aimed at examining whether the disruptive effect of wing-shaped walls occurs in a schematic situation represented on a 2D plane. In this study, we conducted psychophysical experiments in which participants were asked to move a stylus from a start point to a goal while avoiding multiple line obstacles that were arranged alternately at a course. In the two experiments, we manipulated the orientation and the size of the visible parts of the obstacles systematically. We found that the obstacles oriented toward the agent produced frequent contacts with the agent and attracted manual movements to the endpoints of obstacles. We discussed possible interpretations of the results in the context of attentional guidance.
Journal Article
Solar Activity Dependence of the Dayside Lunar Surface Potential in the Terrestrial Magnetotail
2026
On the dayside of the Moon, the surface potential is primarily determined by (a) photoelectron emission by solar radiation and (b) the ambient plasma environment. Both of these drivers have large variability, but the resulting variability of the lunar surface potential has not been fully characterized yet. To investigate the solar activity dependence of the dayside lunar surface potential in the terrestrial magnetotail, we compared long‐term observations of lunar surface photoelectrons with numerical calculations of photo‐emitted electron energy spectra. The comparison demonstrates that the observed solar activity dependence of lunar photoelectrons is well reproduced by the model. The current balance surface potential based on this model predicts more positive potentials for higher solar activities, possibly exceeding +100V${+}100\\ \\mathrm{V}$in the magnetotail lobes during solar flares. These results highlight the importance of evaluating the lunar electrostatic environment under various conditions, including extreme solar events.
Journal Article
Spatiotemporal Characteristics of 360-Degree Basic Attention
2019
The spatiotemporal characteristics of basic attention are important for understanding attending behaviours in real-life situations, and they are useful for evaluating the accessibility of visual information. However, although people are encircled by their 360-degree surroundings in real life, no study has addressed the general characteristics of attention to 360-degree surroundings. Here, we conducted an experiment using virtual reality technology to examine the spatiotemporal characteristics of attention in a highly controlled basic visual context consisting of a 360-degree surrounding. We measured response times and gaze patterns during the 360-degree search task and examined the spatial distribution of attention and its temporal variations in a 360-degree environment based on the participants’ physical position. Data were collected from both younger adults and older adults to consider age-related differences. The results showed the fundamental spatiotemporal characteristics of 360-degree attention, which can be used as basic criteria to analyse the structure of exogenous effects on attention in complex 360-degree surroundings in real-life situations. For practical purposes, we created spherical criteria maps of 360-degree attention, which are useful for estimating attending behaviours to 360-degree environmental information or for evaluating visual information design in living environments, workspaces, or other real-life contexts.
Journal Article
Accelerometer-Based Gait Analysis as a Predictive Tool for Mild Cognitive Impairment in Older Adults
by
Uchino, Katsuhisa
,
Shen, Junwei
,
Harada, Yuki
in
accelerometer
,
Accelerometers
,
Accelerometry - methods
2025
This study explores the potential of accelerometer-based gait analysis as a non-invasive approach for predicting cognitive impairment in older adults. A total of 75 participants (61.3% female; mean age: 78.9 years), including cognitively normal individuals and patients with dementia, were enrolled. Walking data were collected using a six-axis waist-worn accelerometer during self-paced locomotion. Allan variance (AVAR), a robust statistical measure of frequency stability, was applied to characterize gait dynamics. AVAR-derived features, combined with participant age, were used as inputs to machine learning models, logistic regression and Light Gradient Boosting Machine (LightGBM) for classifying cognitive status based on Mini-Mental State Examination (MMSE) scores. LightGBM achieved superior performance (AUC = 0.92) compared to logistic regression (AUC = 0.85). Although mild cognitive impairment (MCI) cases were grouped with cognitively normal participants, gait-based classification revealed that MCI individuals exhibited patterns more similar to those with cognitive impairment. These results suggest that AVAR-based gait features are promising for early detection of cognitive decline in older adults.
Journal Article