The Effects of Hospital Volume on Short-Term Outcomes of Laparoscopic Surgery for Rectal Cancer: A Large-Scale Analysis of 37,821 Cases on a Nationwide Administrative Database.

INTRODUCTION: Laparoscopic low anterior resection (L-LAR) has become widely accepted for the treatment of rectal cancer. However, little is known about the superiority of L-LAR in a real-world setting (including low-volume hospitals) and the association between the short-term outcomes and hospital volume focusing on L-LAR. METHODS: This is a retrospective cohort study. A total of 37,821 patients who underwent LAR for rectal cancer were analyzed using the Diagnosis Procedure Combination (DPC) database from January 2014 to December 2017. The short-term surgical outcomes were analyzed using a multilevel analysis. Hospital volumes were divided into quartiles, including low (1-31), middle (32-55), high (56-91), and very-high volume (92-444 resections per 4 years). The effects of hospital volume on the outcomes were investigated. RESULTS: The study population included 8,335 patients (22%) who underwent open low anterior resection (O-LAR) and 29,486 patients (78%) who underwent L-LAR. The in-hospital mortality and morbidity were consistent with previous reports. In patients who underwent L-LAR, the in-hospital mortality (0.12% vs. 0.41%; OR: 0.33; p = 0.005), the rate of reoperation (3.76% vs. 6.48%; OR: 0.67; p < 0.001), and the perioperative transfusion rate (3.81% vs. 5.90%; OR: 0.66; p < 0.001) were significantly lower in very-high-volume hospitals than in low-volume hospitals. These effects of hospital volume were not observed in O-LAR. CONCLUSIONS: Our present study demonstrates that high volume improves outcomes in patients who underwent L-LAR in a real-world setting.

Increased prevalence of eating disorders in Japan since the start of the COVID-19 pandemic.

PURPOSE: The study aimed to investigate the effect of the COVID-19 pandemic on the prevalence of eating disorders in Japan. METHODS: We retrospectively reviewed the medical records of new patients with eating disorders who visited an outpatient eating disorders clinic of a single university hospital in Tokyo, Japan, from April 2020 to March 2021 (FY2020) and April 2019 to March 2020 (FY2019). We determined whether the onset or course in each patient in FY2020 was associated with the COVID-19 pandemic and classified COVID-19-associated medical histories into the following categories: (1) fatness phobia, (2) acceleration of dieting, (3) family relationships, (4) social factors, and (5) mood change. We performed the Kolmogorov-Smirnov test to compare the cumulative distribution of disease onset by month in FY2020 and FY2019. RESULTS: We reviewed the records of 112 and 77 patients with eating disorders in FY2020 and FY2019, respectively. The onset or course of 35 patients (31.3%) in FY2020 was associated with the COVID-19 pandemic. We classified 14 patients to fatness phobia category, 11 to acceleration of dieting, 4 to family relationships, 2 to social factors, and 4 to mood change. No COVID-19-associated cases were associated with fear of contracting the disease. The cumulative distribution of disease onset differed significantly in FY2020 and FY2019 (D = 0.248; P = 0.007). CONCLUSION: This chart review suggests that the COVID-19 pandemic may increase the prevalence of eating disorders. LEVEL OF EVIDENCE: III, cohort study.

Psychometric properties of the Eating Disorder Examination-Questionnaire and psychopathology in Japanese patients with eating disorders.

OBJECTIVE: The Eating Disorder Examination-Questionnaire (EDE-Q) is one of the most widely used tools to assess the core psychopathology of eating disorders (ED). However, recent empirical findings did not support the original four-factor structure. The aims of the present study were to investigate the factor structure of the EDE-Q in Japanese ED patients, to test the reliability and convergent validity of the EDE-Q, to examine group differences between various ED groups and healthy participants, and to explore the main behavioral features of Japanese ED patients using the newly developed Japanese version of EDE-Q. METHOD: A total of 148 ED patients and 469 healthy participants completed the EDE-Q, Eating Attitudes Test-26 (EAT-26), and Eating Disorder Inventory-2 (EDI-2). The factor structure, reliability, and validity of the EDE-Q were assessed in ED patients. Group differences were assessed using the new Japanese version of the EDE-Q (EDE-Q-J). RESULTS: The EDE-Q-J had three factors. Cronbach's alphas ranged from 0.83 to 0.93. Total score and subscale scores of "Dieting" and "Bulimia and Food Preoccupation" of EAT-26 and of "Drive for Thinness," "Body Dissatisfaction," and "Bulimia" of EDI-2 correlated with the global score and three subscale scores of the EDE-Q-J. DISCUSSION: For Japanese female ED patients, the EDE-Q-J had three subscales that were not consistent with the original subscales, but were interpretable. It demonstrated sufficient reliability and validity. Japanese female patients with restricting-type anorexia nervosa (AN-R) displayed less dissatisfaction with shape and weight than healthy participants. AN-R patients in Japan might present with a non-fat-phobic symptom profile.

Binaural-centered mode-matching method for enhanced reproduction accuracy at listener's both ears in sound field reproduction.

This paper proposes a binaural-centered mode-matching (BCMM) method that performs sound field reproduction with two reproduction points, one at each ear. A sound field reproduced by higher-order Ambisonics converges to the target field around a sweet spot whose size is inversely proportional to the frequency when the truncated order of the spherical harmonic expansion is constant. By contrast, BCMM translates the spherical harmonic coefficients on the basis of the addition theorem to realize two reproduction points at both ear positions. The BCMM method thereby avoids degradation of reproduction due to a smaller sweet spot at higher frequencies, as occurs with the conventional method, and thereby, leads to an accurate reproduction at higher frequencies. A comparison of numerical simulations of the binaural signals obtained when rendering with BCMM and conventional methods shows that, compared with the conventional method, the BCMM method improves the reproduction accuracy.

Effect of acoustically-induced elastic softening on sound absorption coefficient of hollow glass beads with inner closed cavities.

This study investigated the effects of sound wave magnitude on the sound absorption characteristics of granular materials. The normal incidence sound absorption coefficients of the hollow glass bead packings were measured with different incident sound pressure levels. The measurement results exhibited spectral peaks of sound absorption coefficients at several frequencies, implying that the first peak was caused by the resonance of the hollow glass beads as a layer. Although the first peak in the sound absorption coefficients did not vary when an incident sound pressure was low, the first peak shifted to a lower frequency when the sound pressure exceeded a certain magnitude. These results indicate that the hollow glass beads are softened at high incident sound pressures. Furthermore, by modelling the velocity-dependent elasticity of the hollow glass beads, the velocity and elasticity in the hollow glass beads were simulated in the direction of the sound propagation. The simulation results indicate that the velocity and elasticity profiles depend on the sound wave magnitude. Finally, the velocities of the hollow glass beads under acoustic excitation were measured by inserting an accelerometer into the beads. The measurement results demonstrated that the velocity profile depends on the sound wave magnitude, which parallels the simulation results.

Effect of casing on sound absorption characteristics of fine spherical granular material.

To determine sound absorption coefficients of fine granular materials, the materials must be cased to suppress their flowability. In this study, effects of casing on the sound absorption coefficients of fine granular materials were investigated. The normal incidence sound absorption coefficients of cased hollow glass beads were measured using cylindrical impedance tubes. The measurement results demonstrated that the hollow glass beads present a sound absorption peak, which was attributed to the vibration of a particle frame, in the frequency range of 180 to 700 Hz for sample thickness in the range of 20 to 550 mm. With an increase in the material thickness or diameter of the casing, the first peak of the sound absorption coefficients shifted to a lower frequency. The sound absorption coefficients were calculated using an elastic frame model for porous materials. The effects of friction between the lateral wall of the case and the particle frame were incorporated in the bulk modulus and bulk density of the particle frame in the model. The model predicts correctly the frequency at which the first sound absorption peak occurs with an uncertainty of 10%.

Effectiveness of regional clinical pathways on postoperative length of stay for hip fracture patients: A retrospective observational study using the Japanese Diagnosis Procedure Combination database.

BACKGROUND: Regional clinical pathways, a new type of clinical pathway, are practiced with the aim of standardizing and optimizing medical care by cooperation among multiple medical institutions in a region. However, current evaluation of the effectiveness of regional clinical pathways for hip fracture, a major health problem requiring hospitalization for orthopedic surgery, is insufficient. This study aimed to determine the association between regional clinical pathways and postoperative hospital length of stay (LOS) among hip fracture patients. In particular, we focused on the variation in postoperative LOS of hip fracture patients among hospitals and the contribution of regional clinical pathways to this variation. METHODS: Using data from the Diagnosis Procedure Combination (DPC) database in Japan from April 2011 to March 2013, patients who were diagnosed with "fracture of head and neck of femur" (ICD10 code S72.0) or "pertrochanteric fracture" (S72.1) and received "bipolar hip arthroplasty" or "open reduction and internal fixation" were extracted. A total of 110,133 patients were included. Associations between regional clinical pathways and postoperative LOS were analyzed using cross-sectional analysis with multilevel regression models. RESULTS: Hospitals that implemented a regional clinical pathway showed a significant reduction (13 days) in the postoperative LOS of hip fracture patients. We found a 16% inter-hospital variation in postoperative LOS, which might be explained by hospital-level implementation of regional clinical pathways. Application of regional clinical pathways at the patient level resulted in a 4-day decrease in postoperative LOS. CONCLUSIONS: Implementation of regional clinical pathways for hip fracture patients at the hospital level was associated with reduced postoperative LOS, regardless of whether or not pathways were implemented at the patient level. This suggests that regional clinical pathways are effective for patient care management in hospitals.

[Development of a Method for Assignment Control in Randomized Controlled Trials].

Randomized controlled trials (RCT) are the most reliable study design for causality estimation in medical research. Proper implementation of the process of randomization is necessary to ensure the reliability of RCT. In order to do so, 1) generation of randomization sequence, 2) allocation concealment, and 3) allocation must be properly implemented. Methods such as the central secretariat method, the envelope method, and the sequentially numbered container method are adopted to secure proper implementation. For investigator-initiated clinical research and relatively small-scale clinical research, the envelope method and the sequentially numbered container method are often adopted because of budgetary reasons, but these methods do not assure the implementation of proper RCT. Therefore, we designed an assignment management note system as a new method to manage the assignment of RCT that can be implemented in small scale clinical research. In this paper, we compare the assignment management note system with the conventional method from the viewpoint of the procedure necessary for the proper implementation of RCT, and discuss the advantages and limitations of the assignment management note system.

Incidence and In-Hospital Mortality of Neonatal Disseminated Intravascular Coagulation in Japan: An Observational Study of a Nationwide Hospital Claims Database.

This study aimed to estimate the incidence and prognosis of neonatal disseminated intravascular coagulation (DIC) in Japan by analyzing data retrieved from a national administrative database. Clinically, the prognosis of DIC in neonates is poor, but there is little epidemiological data in Japan. This retrospective observational study identified patients diagnosed with neonatal DIC and who were registered in the Japanese diagnosis procedure combination (DPC) database between April 1, 2014 and March 31, 2016. The patients, who were diagnosed with neonatal DIC, included those with ICD-10 code D65 or P60 in primary and secondary diagnosis, with comorbid conditions existing at admission, and with complications occurring after admission. Of 78,073 neonates admitted to 1,474 neonatal intensive care units, 1,864 (2.4%) were diagnosed with DIC. There was no difference between sexes in incidence of DIC; the incidence of DIC was higher in extremely low birth weight infants (9.8%), and significantly higher than that in normal birth weight infants. The overall mean length of hospital stay was longer in neonates with DIC (69.5 days) than in those without DIC (32.6 days, P < 0.001). The number of deaths was 1,156 (1.5%). In-hospital mortality was significantly higher in neonates with DIC (14.1%) than in those without DIC (1.2%, P < 0.001), especially in premature babies. This nationwide study was the first report to investigate the incidence and in-hospital mortality of neonatal DIC in Japan. Neonatal DIC has a significant impact on prognosis, and its influence is greater in premature than in term infants.

Efficacy of Antimicrobial Catheters for Prevention of Catheter-Associated Urinary Tract Infection in Acute Cerebral Infarction.

BACKGROUND: Catheter-associated urinary tract infection (CAUTI) is a common nosocomial infection. However, the effectiveness of antimicrobial catheters in reducing CAUTI in cerebral infarction patients is unknown. The purpose of this study was to determine whether antimicrobial catheters protect against CAUTI in cerebral infarction patients. METHODS: We identified 27,548 patients from the Japanese Diagnosis Procedure Combination Database who had been admitted from April 1, 2012 through March 31, 2014 for acute management of cerebral infarction and had used at least an indwelling urethral catheter. We extracted data on patient sex, age, comorbidity, length of stay, activities of daily living (ADL), surgery, hospital case volume, and catheter type. We defined CAUTI as a urinary tract infection arising during admission. We performed multi-level logistic regression analysis to analyze the reduction in CAUTI using antimicrobial catheters. RESULTS: The rate of CAUTI was 8.8% and 8.3% in the control and antimicrobial catheter groups, respectively. Significant risk factors for CAUTI were age, diabetes requiring insulin therapy, low ADL score, and long hospitalization. Incidence rate was significantly lower in operated cases and those treated with tissue plasminogen activator. For all cases overall, the use of an antimicrobial catheter was not associated with a lower CAUTI rate. However, use was associated with a lower rate of CAUTI in diabetic patients on insulin. CONCLUSIONS: Antimicrobial catheter use was not associated with a lower incidence rate of CAUTI in acute cerebral infarction patients. However, stratified analysis suggested that use was associated with a lower incidence in diabetic patients on insulin.

Coexisting infectious diseases on admission as a risk factor for mechanical ventilation in patients with Guillain-Barré syndrome.

BACKGROUND: The aim of this study was to investigate patient characteristics on admission to hospital that increase the risk of subsequent mechanical ventilation (MV) use for patients with Guillain-Barré syndrome (GBS). METHODS: We extracted data from the Japanese Diagnosis Procedure Combination (DPC) database for 4132 GBS patients admitted to hospital. Clinical characteristics of GBS patients with and without MV were compared. Multivariate logistic regression analyses were performed to estimate the odds ratios (ORs) and 95% confidence intervals (CIs) for the associations of requirement for MV with coexisting infectious diseases, after adjustment for potential confounding variables, age, sex, hospital type, and ambulance transportation. RESULTS: In total, 281 patients required MV, and 493 patients had coexisting respiratory diseases on admission. After adjustment for covariates and stratification by coexisting respiratory diseases, multivariate logistic regression analysis revealed that coexisting cytomegaloviral (CMV) disease (OR 8.81; 95% CI, 2.34-33.1) and herpes simplex viral (HSV) infections (OR 4.83; 95% CI, 1.16-20.1) were significantly associated with the requirement for MV in the group without coexisting respiratory diseases. CONCLUSION: Our findings suggest that coexisting CMV and HSV infections on admission might be significantly associated with increased risk of respiratory failure in GBS patients.

Consultation-Liaison Psychiatry in the General Hospital: the Experience of UK, Italy, and Japan.

Consultation-liaison psychiatry (CLP) is a psychiatric subspecialty addressing the psychological care of medically ill patients as well as the relationship between medical and psychiatric disorders. As a specialty, it has developed over the last 30 years. Yet several cultural and organizational problems in different countries have emerged, including differences regarding implementing CLP services and in the application of CLP guidelines. This paper examines the progress and challenges of CLP in three culturally diverse countries: the UK, Italy, and Japan. In all three countries, the provision of CLP service remains insufficient, and the application of officially acknowledged standards of care is necessary.

Estimation of the low-frequency components of the head-related transfer functions of animals from photographs.

Reliable animal head-related transfer function (HRTF) estimation procedures are needed for several practical applications, for example, to investigate the neuronal mechanisms of sound localization using virtual acoustic spaces or to have a quantitative description of the different localization cues available to a given animal species. Here, two established techniques are combined to estimate an animal's HRTF from photographs by taking into account as much morphological detail as possible. The first step of the method consists in building a three-dimensional-model of the animal from pictures taken with a standard camera. The HRTFs are then estimated by means of a rapid boundary-element-method implementation. This combined method is validated on a taxidermist model of a cat by comparing binaural and monaural localization cues extracted from estimated and measured HRTFs. It is shown that it provides a reliable way to estimate low-frequency HRTF, which is difficult to obtain with standard acoustical measurements procedures because of reflections.

Thrombocytopenia and PT-INR in patients with anorexia nervosa and severe liver dysfunction.

BACKGROUND: We previously reported a case that led us to hypothesize that decreased production of thrombopoietin (TPO) leads to thrombocytopenia in patients with anorexia nervosa (AN) with severe liver dysfunction and that prolonged prothrombin time-international normalized ratio (PT-INR) predicts thrombocytopenia in such cases. To validate this hypothesis, we report another case in which TPO levels were measured. In addition, we examined the association between prolonged PT-INR and thrombocytopenia in such patients. MAIN BODY: Similar to the previously reported patient, a patient with AN with severe liver dysfunction showed that TPO levels increased after improvements in liver enzyme levels and PT-INR, followed by recovery of platelet count. In addition, a retrospective study was also conducted to review patients with AN whose liver enzyme levels were > 3 × the upper limit of normal (aspartate aminotransferase > 120 U/L or alanine aminotransferase > 135 U/L). The study included 58 patients and showed a correlation coefficient of -0.486 (95% confidence interval [CI], -0.661 to -0.260; P < 0.001) between maximum PT-INR and minimum platelet count. These patients showed higher PT-INR (ß, 0.07; 95% CI, 0.02 to 0.13; P = 0.005) and lower platelet count (ß, -5.49; 95% CI, -7.47 to -3.52; P < 0.001) than the 58 matched control patients without severe liver dysfunction, even after adjusting for body mass index. CONCLUSIONS: In patients with AN with severe liver dysfunction, prolongation of PT-INR could predict thrombocytopenia, which may be mediated by decreased TPO production due to decreased hepatic synthetic function.

Development and preliminary validation of the Group Cognitive Therapy Scale.

Aim: The aim of this research was to create a scale to assess the competency of therapists who conduct group cognitive behavioral therapy (G-CBT). The scale is intended to serve as a tool to aid the training of therapists. Methods: Three stepped studies were conducted. Process 1: Through literature review and experts' consensus process, essential skills for G-CBT were articulated and categorized according to the criteria of the Cognitive Therapy Scale, a well-established rating scale for evaluating clinicians' skills in individual cognitive behavioral therapy. The list of those skills was organized into a rating scale. Process 2: Behavioral anchors were added to each skill and were classified by the levels of difficulty (beginner, intermediate, and advanced levels), based on the rating by G-CBT experts. Process 3: Inter-rater reliability and validity of the rating scale were examined in a sample of 41 videotaped G-CBT sessions of actual clinical sessions and educational role-plays. Results: The 12-item Group Cognitive Therapy Scale (G-CTS) was developed. It consists of 11 items that are adapted from the original Cognitive Therapy Scale, and a new 12th item called "Intervention using relationships with other participants," which describes therapists' skills to address group dynamics. The G-CTS showed excellent internal consistency (Cronbach's α: 0.95), satisfactory inter-rater reliability (interclass correlation coefficients: 0.65-0.88), and high predictive validity. Conclusion: A novel rating scale to evaluate therapists' competency in G-CBT was developed and successfully validated. The G-CTS behavioral checklist created in this study provides concrete guidelines that can be used by therapists to hone their skills in G-CBT.

Mechanical and oral antibiotics bowel preparation for elective rectal cancer surgery: A propensity score matching analysis using a nationwide inpatient database in Japan.

Aim: The best bowel preparation method for rectal surgery remains controversial. In this study we compared the efficacy and safety of mechanical bowel preparation (MBP) alone and MOABP (MBP combined with oral antibiotic bowel preparation [OABP]) for rectal cancer surgery. Methods: In this retrospective study we analyzed data from the Japanese Diagnosis Procedure Combination (DPC) database on 37 291 patients who had undergone low anterior resection for rectal cancer from 2014 to 2017. Propensity score matching analysis was used to compare postoperative outcomes between MBP alone and MOABP. Results: A total of 37 291 patients were divided into four groups: MBP alone: 77.7%, no bowel preparation (NBP): 16.9%, MOABP: 4.7%, and OABP alone: 0.7%. In propensity score matching analysis with 1756 pairs, anastomotic leakage (4.84% vs 7.86%, P < 0.001), small bowel obstruction (1.54% vs 3.08%, P = 0.002) and reoperation (3.76% vs 5.98%, P = 0.002) were less in the MOABP group than in the MBP group. The mean duration of postoperative antibiotics medication was shorter in the MOABP group (5.2 d vs 7.5 d, P < 0.001) than in the MBP group. There was no significant difference between the two groups in the incidence of Clostridium difficile (CD) colitis (0.40% vs 0.68%, P = 0.250) and methicillin-resistant Staphylococcus aureus (MRSA) colitis (0.11% vs 0.17%, P = 0.654). There was no significant difference in in-hospital mortality between the two groups (0.00% vs 0.11% respectively, P = 0.157). Conclusion: MOABP for rectal surgery is associated with a decreased incidence of postoperative complications without increasing the incidence of CD colitis and MRSA colitis.

Development of a Japanese Version of the Quality of Life at the End of Life-Cancer Scale.

CONTEXT: The Quality of Life at the End of Life-Cancer Scale (QUAL-EC) is a self-reported instrument to assesses the quality of life of patients with cancer near the end of life. OBJECTIVE: To test the reliability and validity of the QUAL-EC-J, a Japanese translated version of the QUAL-EC. METHODS: A total of 179 Japanese patients with advanced cancer completed the QUAL-EC-J, Patient Health Questionnaire-9, Generalized Anxiety Disorder-7, Rosenberg Self-Esteem Scale, Multidimensional Scale of Perceived Social Support, Functional Assessment of Cancer Therapy-General Scale, and Functional Assessment of Chronic Illness Therapy-Spiritual questionnaires. We performed confirmatory factor analysis of the four structures of the QUAL-EC and exploratory factor analysis of the QUAL-EC-J. Internal consistency was assessed using Cronbach's α coefficient and validity was examined by calculating correlations with relevant scales. RESULTS: Confirmatory factor analysis showed an inadequate fit to the original QUAL-EC structure. Exploratory factor analysis revealed a three-factor structure of the QUAL-EC-J, with Cronbach's α values of 0.68-0.88. All subscales were negatively correlated with depression and anxiety. Each subscale was correlated with related measures: "symptom control" with "physical well-being"; "acceptance of disease and life" with "social and family well-being" and "meaning/peace"; and "preparation for end of life" with "emotional well-being" and "meaning/peace." CONCLUSIONS: The QUAL-EC-J has a three-factor structure with acceptable reliability and sufficient validity. Differences in the factor structure between the QUAL-EC-J and the QUAL-EC may be due to cultural factors. Study findings suggest that utilization of the QUAL-EC-J could help to improve research and clinical care in advanced cancer in Japan.

Economic costs for outpatient treatment of eating disorders in Japan.

BACKGROUND: Few studies have examined the economic costs of outpatient care for eating disorders in Japan. This study aimed to clarify the reimbursement for outpatient treatment of eating disorders and compare the costs between the departments of Psychosomatic Medicine and Psychiatry in Japan. METHOD: A multicenter, prospective, observational study of patients with an eating disorder was conducted in the Psychosomatic Medicine departments of three centers and the Psychiatry departments of another three centers in Japan. We analyzed medical reimbursement for an outpatient revisit, time of clinical interviews, and the treatment outcome measured by the Eating Disorder Examination Questionnaire (EDE-Q) global scores and body mass index (BMI) at 3 months. Multivariate linear regression models were performed to adjust for covariates. RESULTS: This study included 188 patients in the Psychosomatic Medicine departments and 68 in the Psychiatry departments. The average reimbursement cost for an outpatient revisit was 4670 yen. Even after controlling for covariates, the Psychosomatic Medicine departments had lower reimbursement points per minute of interviews than the Psychiatry departments (coefficient = - 23.86; 95% confidence interval = - 32.09 to - 15.63; P < 0.001). In contrast, EDE-Q global scores and BMI at 3 months were not significantly different between these departments. CONCLUSIONS: This study clarifies the economic costs of treating outpatients with eating disorders in Japan. The medical reimbursement points per interview minute were lower in Psychosomatic Medicine departments than in Psychiatry departments, while there were no apparent differences in the treatment outcomes. Addressing this issue is necessary to provide an adequate healthcare system for patients with eating disorders in Japan.

This study examined the cost of outpatient care for eating disorders in Japan, comparing treatment costs between the Psychosomatic Medicine and Psychiatry departments. The actual cost of outpatient care for eating disorders in Japan was clarified. The results indicate that Psychosomatic Medicine departments have lower reimbursement points per interview time compared to the Psychiatry departments, but there were no noticeable differences in treatment outcomes between the two. This highlights the need to address this cost difference to improve the healthcare system for patients with eating disorders in Japan.

Spatial auditory presentation of a partner's presence induces the social Simon effect.

Social presence is crucial for smooth communications in virtual reality (VR). Current telecommunication systems rarely submit spatial auditory information originating from remote people. However, such information may enhance social presence in VR. In this study, we constructed a dynamic binaural synthesis system and investigated the effect of spatial auditory information of a remote partner on a participant's behavior using the social Simon effect (SSE). The SSE is a spatial stimulus-response compatibility effect between two persons. The SSE occurs when one perceives that their partner is present. Several studies have confirmed the SSE in actual environments. We presented partner sounds diotically (i.e., without spatial information) to one group or binaurally (i.e., with spatial information) to another group through headphones without providing visual information about the partner. The results showed that the SSE was induced only in the binaural group in the current auditory VR (Experiment 1), whereas both groups exhibited the SSE in an actual environment (Experiment 2). These results suggest that the auditory spatial information of remote people is sufficient to induce the SSE and has a potential to enhance social presence.