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ABSTRACT
The purpose of this study was to use Virtual Reality(VR) and electrocardiograms (ECGs) to analyse differences in autonomic nervous responses affected by the plan configuration. Four different plan configurations of single-person households were chosen based on a prior study and built using VR. An ECG was then recorded within each plan type and the average low-frequency/high-frequency (LF/HF) power ratio was calculated to measure the stress level in each space, and the results revealed significant differences among plan type(p < 0.05). These results provide compelling evidence that a plan configuration may affect the quality of space for single-person households and also suggest that choice of plan configuration appears to be effective in counteracting the stress that may exacerbate psychological disorders among single-person households.
Disclosure statement
No potential conflict of interest was reported by the authors.
Notes
1 The Unreal Engine was chosen to build VR stimuli: first, it is an integrated game engine that provides overall game development environments. Second, it has been used in dozens of video game development worldwide based on its outstanding design visualization and technical skills. Third, from 1994 to present, it has been used by many users for a long time by including continuous updates, various technical support, and excellent development tools. Therefore, it would be easier to build realistic VR space for this study in a relatively short time based on its excellent technology.
2 Alienware M51 was used to present stimuli since the visual reality of the constructed VR stimuli is heavily dependent on the graphics performance of the computer. Therefore, among the most powerful gaming notebook line from Alienware which is a subsidiary of the US computer hardware Dell, the latest version of the Alienware M51 released in 2019 was chosen for this study because it offers excellent graphics upgrade possibilities.
3 Oculus Rift, which is one of the virtual reality head-mounted displays has a wide field of view with a resolution of 1080 × 1200 on both the right and left sides. Since it also includes a function to track rotations and positions, when the participant turns their head while they are experiencing VR, the experimenter can also view the relevant VR scene on the computer screen. Therefore, it was deemed appropriate for this study.
4 This document introduces the subjective evaluation method as a method for quantifying and evaluating the extremely vague sensibility that an individual feels subjectively. According to the book, the result from the subjective evaluation is different from those obtained by simple surveys. And there are four ways to apply subjective evaluation: size estimation(ME), normalization ranking, one-to-one comparison, and semantic differentiation (SD). Although, there are various analysis methods including simple questionnaire analysis methods such as RM-ANOVA, but we chose the subjective evaluation method based on the theoretical book. More specifically, a normalized rank method was used to measure emotional changes according to the plan configuration for the following reasons.
Since the aim of this research is to investigate the effect of plan configuration on humans using ECG, we thought it is better to use the ‘symbol type’ rather than ‘analytic type’. (And the normalized ranking method is one of the ‘symbol type’) According to the book, the subjective evaluation method is further divided into ‘analytic type’ and ‘symbol type’ according to the characteristics of the analysis method. The ‘analytic type: the size estimation(ME)’ is used to quantify the physical strength of stimuli regardless of the emotional pattern caused by the stimuli. On the other hand, the focus of ‘symbolic type: normalization ranking method, one-to-one comparison method, and semantic differential method (SD)’ is to check the congruency of the stimulus for the scale (reference) set by research.
Thus, we thought ‘symbol type’ suited better for the research purposes of this manuscript, since the aim of this research is to investigate the effect of plan configuration on humans using ECG(the scale). Further, the normalized ranking places a lower compulsory burden on the subject and involves less computation for analysis than other methods. For that reason, it can be easily conducted, so it was used in many studies. Since the reliability of this method was proved in many studies. Moreover, the normalized ranking method provides more than a simple ranking comparison. It not only compares each stimulus by ranking but also quantifies the difference between the stimuli and analyzes the result statistically. Since it is more objective to use the quantitative and statistical method, we chose the normalized raking method.
5 The significance level check (t0) expression uses the variance (S²) value and Rx –Ry. Here, Rx denotes a scale value of stimulus x, and Ry denotes a scale value of stimulus y. Through this, it can be mentioned that there is a significant difference between the two stimuli in the significance level if the final (t0) value is larger than the t value. However, if the (t0) value is smaller than the t value, it can be said that no significant difference is observed between the stimuli at the significance level and there is no statistical difference between the stimuli.
6 In the variance (S²) equation, Kel means the deviation rate. The deviation rate Kel is for indicating how far the value of the percentile value in each stimulus is from the average value Kel of the whole percentile value, and can be obtained using a normal distribution table. In the normal distribution table, select the second decimal place of the value as the row and the third decimal place as the column. The value at that intersection is Kel. Next, R in the expression means a scale value. The scale value R represents the degree of agreement with the evaluation criteria of each stimulus. By using this value, each stimulus can be arranged on one scale. In other words, the order of magnitude of this scale value meets the criteria of the one investigated in this experiment.
7 Long / short length entrance types: According to the length of the entrance side of the studio, in cases where the length of the entrance side is longer than the length of the side perpendicular to the foregoing, the studio is called long side type and in the opposite case, the studio is called short side type.
8 Adjacent / Separated Type: According to the relationship between the bathroom (B) and the kitchen (K), in cases where the B and K are adjacent, the studio is called an adjacent type, and in opposite cases, the studio is called a separated type.
9 Vertical / horizontal type: According to the locations of the bathroom (B) and the kitchen (K), in cases where the B and K are located vertically, the studio is called a vertical type, and in cases where the B and K are located horizontally, the studio is called a horizontal type.
10 BK / KB type: According to the order of the bathroom (B) and the kitchen (K) seen after entry, the studio is called a BK type (bathroom → kitchen) or KB type (kitchen → bathroom).
11 Once the path is changed, BK will become KB from the human perspective. However, space itself, which was shaped by the real-location and order of ‘B’ and ‘K’ would not be changed (as well as the spatial perception from it). In particular, since ‘B’ needed to be closed space to perform its architectural function, in the room starting with ‘B’, people would experience a small and narrow space in the entrance and experience openness for later (Imagine room impression caused by Plan B as the reference). On the other hand, since ‘K’ does not require closed space to perform its architectural function, it is usually planed as open space without the wall (especially in a small room like single-person housing). So in the room starting with ‘K’, people experience an open space in the entrance and experience blocked space for later (Imagine room impression caused by Plan J as the reference).
12 Since the “BK” and “KB” variable fixes the shape of the room according to its architectural function, we strongly believe that it is meaningful to discuss is. So, we conducted group anlysis using “BK” and “KB” variable although sample size does not match perfectly (Among the four plans selected in this study, three are “BK” and only one is “KB”. “KB” has only one single sample). We agree that the author should consider the number of samples during the plan selection stage. However, it is clearly not always possible in every case. We chose stimuli based on the result of the previous study. In other words, even though it was found that there is a small number of samples in one category, it is impossible to change the stimuli because we can’t change the result of the previous study. We believe that the analysis of this section will help people to compare the result of this study to the previous study. Regardless, though, we do aware of the fact that there can be a possible bias on this part of the analysis and we clearly mentioned it in the paper.
13 The main goal of ergonomics is to examine differences, interpret and integrate them according to people’s activity environment by applying both subjective evaluation methods(emotional data) and objective evaluation methods(physiological response data). In fact, the subjective evaluation method (as subjective data) and the objective evaluation method (as objective data) were applied differently in the earlier period of Ergonomics. Recently, however, studies applying both subjective and objective methods have become mainstream.