# Quantifying Emotions in Architectural Environments Using Biometrics
## 3 Analysis of Selected Papers
### Outcomes
#### 3.4.2 Biometric Indicators and Interpretation  
This paper investigated the use of biometric tools to measure positive emotion. An emotional experience is a reaction to a stimulus that processes the subcortical and cortical brain networks [3]. Emotional states are identified through individual patterns of central nervous system response [42]. Furthermore, the intensity of an emotional expression is measured by brain waves [43]. Since this study views human emotion as an action in response to an elicitor [43], neurophysiological emotions are measured through neuroimaging techniques indicating both the central nervous and autonomic nervous systems.  
For EEG, 40% of the oscillations in the time domain were higher across all channels in the positively configured environment (stress-reducing) than in the negatively configured environment (stress-inducing). The raw EEG data were first normalized against baseline signals to bring the different data to a comparable scale. For EEG, higher theta and alpha bands are related to meditation and relaxation, especially for frontal channels (i.e., F3/F4 and F7/F8). In contrast, lower beta band power (14-40 Hz) is associated with active, busy, or anxious thinking. fMRI images of people viewing pleasurable images show activation of the precuneus, middle frontal gyrus, and anterior cingulate cortex [34]. With ECG, higher rates of HRV indicate anxiety and thus refer to negative emotion. The experience of pleasure can also be measured by EMG, where the zygomaticus major muscle is associated strongly with feelings of happiness [23]. For eye-tracking, research results confirmed that the pupil diameter relates to emotional assessment, with an increase in the diameter typical of positive experience and a decrease in the diameter typical of negative experience [12]. For GSR data, SCR was higher in the hostile environment, indicating stress, and the average number of peaks in a positively configured environment increased by 154% from a stress-reducing climate to a stress-inducing one. Participants showed more reductions in BP and SCL from baseline when a biophilic atmosphere is compared to a non-biophilic environment [37]. AVNN, the average N-N interval, HRV features' metrics also showed higher for the stress-reducing environment, indicating more relaxation.  
Some papers demonstrated inconsistent results. One inconsistency was seen in anxiety levels. A high average peak elevation of GSR levels, indicating high anxiety, was correlated with the self-assessed experience of pleasure [5]. While in other cases, high relaxation and thus low anxiety were related to happiness. Thus, the lack of uniform protocol and consistency across results in data analysis procedures leads to inconclusive results. There could also be a discrepancy between the subjective and objective outcomes. For example, in one study, the finding that experts in design preferred sharp-angled spaces while non-experts preferred curvilinear was confirmed by traditional measuring methodology (questionnaires and observations) [31]. However, the same result was not distinctly recognized in the biodata captured and thus significance was reduced.  
Eye-tracking devices used to analyze visual attention and emotional arousal in response to architectural components and interior design elements [28]. In addition, a comparative study could be conducted to distinguish the level of attention of different sectors of groups representing an archetype, with results revealing the characteristics of each group. Such a study design can reflect the primary interests in the architectural research field.