- Press Release Distribution

Exploring the effect of the presence of familiar people in interpersonal space

Researchers investigate the influence of social relationships on our bodily responses to the presence of other persons in the interpersonal space

Exploring the effect of the presence of familiar people in interpersonal space

When we communicate with other people face-to-face, we do so by maintaining a certain physical distance from each other. This space surrounding our body while interacting is called the interpersonal space (IPS), and maintaining adequate IPS is crucial for better communication.

Many studies have investigated the psychological and physiological changes that occur based on the presence of another person in the IPS during face-to-face interactions. These studies are based on the avoidance behaviour that we experience when a stranger invades our IPS, which manifests in the form of increased heart rate and discomfort. However, having a social relation with a person, such as with a friend or a spouse, can influence this behaviour. Moreover, most studies have only examined IPS in front of or behind a person, using tasks such as a stopping task, wherein a stranger approaches or retreats from the IPS. They have not determined the shape of IPS by considering different relative positions around a person.

Addressing this gap, a team of researchers from Japan, led by Assistant Professor Kae Mukai from the Faculty of Science and Engineering at Waseda University, investigated the effect of social relationships on the physiological and psychological responses to the presence of another person in the IPS. Dr. Mukai explains, “Considering a real-life situation in which acquaintances or friends are standing next to us, the threat level might be relatively low compared to when strangers are standing next to us. Given the evidence, that smaller IPSs may be formed with family and friends, psychological and physiological responses can differ. In this study, we uncovered these differences.” The team also included Dr. Tomoko Isomura from Nagoya University and Dr. Ryoji Onagawa and Professor Katsumi Watanabe from Waseda University. Their findings were published in the journal Scientific Reports on February 21, 2024.

The researchers used electrocardiogram (ECG) data to measure the changes in subjective discomfort, heart rate, and heart rate variability (HRV), which indicates parasympathetic activity or the “rest and digest” nervous response, of a person due to the presence of another person at various relative positions in the IPS. They measured these changes during two tasks. In the first task, participants were paired with their friends in a static standing task, where a person stood 30 cm away from the other, with both hands behind their back, within the IPS for a minute.

There were eight relative positions in all: F-see, L-see, R-see, and B-see, as well as F-seen, L-seen, R-seen, and baseline. In the first case, participants stood face-to-face with their friend and looked at the center of their eyes. In the next three cases, they looked at their friend’s left profile, right profile, and back, respectively, with their eyes fixed on the head. On the other hand, the participants stood with their eyes fixed on the fixation point 30 cm in front of them while being seen at their left profiles, right profiles, and backs by their friend in F-seen, L-seen, and R-seen conditions, respectively. Lastly, in the baseline condition, both persons were standing back-to-back, unable to see each other. In the second task, a cylindrical object with height same as that of the person was placed at different positions in the IPS.

The experiments revealed that the greatest discomfort, the greatest decrease in heart rate, and the greatest increase in HRV occurred in the F-see condition. The researchers attributed the decrease in heart rate and increase in parasympathetic activity to the presence of familiar people, as previous studies have shown that the presence of a friend or romantic partner activates parasympathetic activity. Moreover, they found that heart rate only decreased in relative positions F-see and R-see. Additionally, no changes were observed during the task with the object.

These findings are inconsistent with previous studies which report that sympathetic activity, or the “fight or flight” response, is activated when a stranger invades our personal space. “Our study suggests that social relationships between two people influence our physiological responses during social interactions,” says Dr. Mukai. “Our findings could help in the development of a society that makes life easier for a diverse range of people, by introducing appropriate communication methods that vary according to changes in responses to the presence of others.”






Authors: Kae Mukai1,2, Tomoko Isomura3, Ryoji Onagawa1,2, and Katsumi Watanabe1


1Faculty of Science and Engineering, Waseda University, Japan

2Japan Society for the Promotion of Science, Japan

3Graduate School of Informatics, Nagoya University, Japan



About Waseda University

Located in the heart of Tokyo, Waseda University is a leading private research university that has long been dedicated to academic excellence, innovative research, and civic engagement at both the local and global levels since 1882. The University has produced many changemakers in its history, including nine prime ministers and many leaders in business, science and technology, literature, sports, and film. Waseda has strong collaborations with overseas research institutions and is committed to advancing cutting-edge research and developing leaders who can contribute to the resolution of complex, global social issues. The University has set a target of achieving a zero-carbon campus by 2032, in line with the Sustainable Development Goals (SDGs) adopted by the United Nations in 2015. 

To learn more about Waseda University, visit  


About Assistant Professor Kae Mukai

Kae Mukai is currently an Assistant Professor at the Faculty of Science and Engineering at Waseda Research Institute for Science and Engineering in Waseda University in Japan. He obtained his Ph.D. from the University of Tokyo in 2020. He is also a member of the Japan Society for the Promotion of Science. His research interests include humanities, social sciences, cognitive science, life sciences, and sports psychology.


[Attachments] See images for this press release:
Exploring the effect of the presence of familiar people in interpersonal space Exploring the effect of the presence of familiar people in interpersonal space 2 Exploring the effect of the presence of familiar people in interpersonal space 3


California leads U.S. emissions of little-known greenhouse gas

California leads U.S. emissions of little-known greenhouse gas
California, a state known for its aggressive greenhouse gas reduction policies, is ironically the nation’s greatest emitter of one: sulfuryl fluoride.  As much as 17% of global emissions of this gas, a common pesticide for treating termites and other wood-infesting insects, stem from the United States. The majority of those emissions trace back to just a few counties in California, finds a new study led by Johns Hopkins University. “When we finally mapped it out, the results were puzzling because the emissions were all coming from one place,” said co-author Scot ...

SLAC completes construction of the largest digital camera ever built for astronomy

SLAC completes construction of the largest digital camera ever built for astronomy
Menlo Park, Calif. — After two decades of work, scientists and engineers at the Department of Energy's SLAC National Accelerator Laboratory and their collaborators are celebrating the completion of the Legacy Survey of Space and Time (LSST) Camera. As the heart of the DOE- and National Science Foundation-funded Vera C. Rubin Observatory, the 3,200-megapixel camera will help researchers observe our universe in unprecedented detail. Over ten years, it will generate an enormous trove of data on the southern night sky that researchers will ...

When tickling triggers more than just laughter

Scientists at the Institute of Pathophysiology of the University Medical Center Mainz made the first comprehensive analysis on how adults use tickling in connection with sexual activity. As part of their study, they surveyed 719 people with a so-called tickling fetish. The results of the study show that human sexuality encompasses a variety of forms of expression that need to be studied and understood in greater depth. Most people laugh when they are tickled. But there are also individuals for whom tickling or being tickled triggers sexual arousal. This sexual preference is referred to as a tickle ...

Unfavorable social factors may raise heart disease risk factors in Asian American adults

Research Highlights: Asian American adults with more unfavorable factors related to income level, education, housing, access to health care and other social variables had a greater likelihood of having risk factors for cardiovascular disease in this study. The relationship between social determinants of health and cardiovascular disease risk factors varied widely among some Asian American subgroups, based on the study’s findings. Embargoed until 4 a.m. CT/5 a.m. ET Wed., April 3, 2024 DALLAS, April 3, 2024 — Having more unfavorable social determinants of health, such as being unemployed, uninsured or not having education beyond high school, ...

AI helps to detect invasive Asian hornets

AI helps to detect invasive Asian hornets
Artificial Intelligence can be used to detect invasive Asian hornets and raise the alarm, new research shows. University of Exeter researchers have developed VespAI, an automated system that attracts hornets to a monitoring station and captures standardised images using an overhead camera. When an Asian hornet visits, VespAI can identify the species with almost perfect accuracy – allowing authorities to mount a rapid response. Asian hornets (also known as yellow-legged hornets) have already invaded much of mainland Europe and parts of east Asia, and have recently been reported in the US states of Georgia and South Carolina. The ...

Pressure determines which embryonic cells become ‘organizers’

Pressure determines which embryonic cells become ‘organizers’
(Santa Barbara, Calif.) — A collaboration between research groups at the University of California, TU Dresden in Germany and Cedars-Sinai Guerin Children’s in Los Angeles has identified a mechanism by which embryonic cells organize themselves to send signals to surrounding cells, telling them where to go and what to do. While these signaling centers have been known to science for a while, how individual cells turn into organizers has been something of a mystery. Until now. In a paper published in the journal Nature ...

Global rollout of Skin Observer by NAOS and Haut.AI in 2024

Global rollout of Skin Observer by NAOS and Haut.AI in 2024
Tallinn, 3rd April 2024 - 10 AM CET – NAOS, the French founding company behind pioneering ecobiological skincare brands BIODERMA, Etat Pur, and Institut Esthederm, introduces its innovative new digital tool Skin Observer in collaboration with Haut.AI, a leader in AI applications for skincare and skin aging. The partnership merges cutting-edge AI technology with deep expertise in skin ecobiology.  Developed in collaboration with dermatologists, NAOS Skin Observer offers quick and precise skin analysis, recommending customized rituals adapted to individual skin types. The system adjusts routines based on user preferences, dynamic skin ...

New Paradigm of Peace through Health: Traditional Medicine Meditation in the Prevention of Collective Stress, Violence, and War

A breakthrough perspective article in Frontiers in Public Health, "Peace through Health: Traditional Medicine Meditation in the Prevention of Collective Stress Violence and War," sheds light on the profound impact of the Transcendental Meditation (TM) program on fostering global peace. The article reviews and analyzes the demand for public health and medicine to help prevent collective violence and “intractable” wars in the Middle East, Eastern Europe, Africa and elsewhere and ...

Machine learning enables viability of vertical-axis wind turbines

Machine learning enables viability of vertical-axis wind turbines
If you imagine an industrial wind turbine, you likely picture the windmill design, technically known as a horizontal-axis wind turbine (HAWT). But the very first wind turbines, which were developed in the Middle East around the 8th century for grinding grain, were vertical-axis wind turbines (VAWT), meaning they spun perpendicular to the wind, rather than parallel. Due to their slower rotation speed, VAWTs are less noisy than HAWTs and achieve greater wind energy density, meaning they need less space for ...

E-cigarette users now more likely to quit traditional cigarettes

A new paper in Nicotine & Tobacco Research, published by Oxford University Press, finds that smokers who switch to electronic cigarettes are now more likely to stop smoking regular cigarettes. In the past, smokers who began using electronic cigarettes mostly continued smoking. Electronic nicotine delivery systems first emerged on the U.S. market in 2007. The first e-cigarettes resembled conventional cigarettes (in appearance) and used fixed low-voltage batteries. Beginning in 2016, manufacturers introduced e-liquids containing nicotine salt formulations. These new e-cigarettes became widely available. These nicotine salts are lower in pH than freebase formulations, which allow manufacturers ...


Most massive stellar black hole in our galaxy found

New review offers first recommendations on accurately assessing the carbon footprint of coffee farming

Seed ferns: Plants experimented with complex leaf vein networks 201 million years ago

New statewide research reveals the staggering economic cost of intimate partner violence in Louisiana

From ashes to adversity: Lessons from South Australia's business recovery amidst bushfires and pandemic

Multiple pollutants from crop and livestock production in the Yangtze River: status and challenges

Unraveling the unique role of DELLA proteins in grapevine flowering: A shift in developmental fate

Next-generation treatments hitch a ride into cancer cells

Unraveling the role of DlBGAL9 and AGL61/80 in Longan somatic embryogenesis and heat stress tolerance: A multi-omics approach

Decoding pecan pollination: A dive into the chloroplast genome of 'Xinxuan-4' and its impact on cultivar diversity and efficiency

KD-crowd: A knowledge distillation framework for learning from crowds

Can animals count?

Australian media need generative AI policies to help navigate misinformation and disinformation

Illuminating the path to hearing recovery

Unlocking the secrets of fruit quality: How anthocyanins and acidity shape consumer preferences and market value

Evidence for reversible oxygen ion movement during electrical pulsing: enabler of the emerging ferroelectricity in binary oxides

Revolutionizing Citrus cultivation: The superior tolerance and growth vigor of 'Shuzhen No.1' rootstock

Family and media pressure to lose weight in adolescence linked to how people value themselves almost two decades later

Despite the desire to reduce the risk of imitation, new research suggests startups should scale slowly and steadily

The Lancet: Many people with breast cancer ‘systematically left behind’ due to inaction on inequities and hidden suffering

From opioid overdose to treatment initiation: outcomes associated with peer support in emergency departments

NIH awards $3.4 million to Wayne State University to investigate biomarkers for better reproductive success

New study shows corporate misconduct at home hurts sales overseas

Take it from the rats: A junk food diet can cause long-term damage to adolescent brains

Fralin Biomedical Research Institute team unpacking genetic mysteries of childhood epilepsies

UNC-Chapel Hill researchers discover new clues to how tardigrades can survive intense radiation

UT Arlington prioritizes entrepreneurship efforts

Ochsner Health receives 2024 Top Workplaces Culture Excellence Awards

Are these newly found rare cells a missing link in color perception?

Annals supplement highlights important new evidence readers ‘may have missed’ in 2023

[] Exploring the effect of the presence of familiar people in interpersonal space
Researchers investigate the influence of social relationships on our bodily responses to the presence of other persons in the interpersonal space