# Quantifying Emotions in Architectural Environments Using Biometrics
## 3 Analysis of Selected Papers
### Intervention and Comparators  
This paper classified interventions as variables being tested for, which included design characteristics in the architectural environment, such as form, layout, color, material, furniture, and lighting. The included papers measured the impact of the design characteristics on emotional responses using biometric tools such as EEG, fMRI, ECG, EMG, GSR, and eye-tracking. * Form Regarding form, one study investigated how systematic variations in contour (e.g., curvilinear or rectilinear spaces) affect aesthetic judgments and approach-avoidance decisions using fMRI [34]. The parametric analyses of pleasantness and beauty suggested that the two variables activated dissociable aspects of the same network in the aesthetic judgment of a visual stimulus [34]. The studies involving first-order polynomial expansions showed that activation in the precuneus, middle frontal gyrus, and anterior cingulate cortex (ACC) co-varied pleasantness ratings [34]. Another study arrived at a similar conclusion with another bio-tool. Curvilinear spaces accompanied greater pleasure and activated the \(\theta\) activity in or near the ACC, as observed from EEG data [25]. The group with higher pleasure and arousal ratings recorded higher \(\theta\) activity (3-7 Hz) near the ACC (Cls 24). A partial correlation controlling for arousal and pleasure was conducted to control for the effect of affective processes, from which changes in the ACC theta band activity were shown to be caused by processing aspects of architectural features in the built environment and not by the arousal or valence of the form features [25]. * Layout Using psychophysiological metrics with self-report, the effect of visual complexity on affective/behavioral responses was measured. The visual complexity was manipulated with patterns and layout [23]. * Material Regarding material, wooden material has a positive impact on the nervous system. The brain becomes calmer and less stressed, while longer exposure results in a more active brain, making the participants less afraid and anxious and increasing their memory and ability to think. Such experience is accompanied by the EEG beta wave change that initially decreases and then significantly increases after more prolonged exposure [29]. Additionally, natural elements, such as biophilic designs, reduce stress and anxiety and improve physiological and cognitive performance [37; 38]. * Color The variations in color schemes were used to assess emotional responses such as pleasure, arousal, relaxation, and comfort. For effective assessment, the colors of a scene can be classified into easily recognized categories. One of the models used in a study was the HSV color model, which utilizes color parameters such as hue (H), saturation (S), and value (V) and approximates how the human visual system perceives colors [40]. Another study compared the brightness of color. The study found that bright color, with light-bounce intensity above average (2.0 in Unity 3D), increased oscillations in the \(\alpha\), \(\beta\), and \(\theta\) frequency bands for EEG measures, lowered the average number of SCR peaks, and resulted in less perspiration and heart rate variability [5]. Two studies compared monotone and multitone environments. One study concluded that both colorful and gray environments induce unpleasant experiences [30]. Another study examined the psychological and physiological effects of colored room interiors on people [33]. The participants were given activities to do, such as work or leisure [33]. The study was designed to measure experiences and the result differed according to the function of the room. In a space for work, subdued colors were preferred, while for leisure, gray and bright colors were preferred [33]. Likewise, blue was seen as more pleasant across several studies and accompanied the decrease of heart rate [24; 27]. The decrease of heart rate is associated with the relieving of stress-levels [27].