BIOPHILIC DESIGN IN RESIDENTIAL ENVIRONMENTS: EXPLORING EMOTIONS, RESTORATIVENESS, AND SATISFACTION By Evan Cameron A THESIS Submitted to Michigan State University in partial fulfillment of the requirements for the degree of Environmental Design - Master of Arts 2025 ABSTRACT This study explores how varying levels of biophilic implementation can influence emotional and behavioral responses within residential interiors. A total of 150 complete survey responses were collected from participants who viewed digital images of an interior living space that displayed varying amounts of indoor plants (control, moderate, and intense). Participants provided self-reported responses regarding their emotions (pleasure and arousal), perceived restorativeness, satisfaction, and willingness to stay. Results showed that perceived levels of pleasure, restorativeness, satisfaction, and willingness to stay all increased with levels of greenery. Arousal peaked at the moderate level of greenery which suggests there is a threshold that is preferred by occupants. These findings support current literature on biophilic design and related theories such as the pleasure & arousal framework and attention restoration theory, and provide the opportunity to further understand the effects of biophilic practices on users’ wellbeing and spatial preferences in residential environments. TABLE OF CONTENTS CHAPTER 1: INTRODUCTION ...................................................................................................1 CHAPTER 2: LITERATURE REVIEW ........................................................................................5 CHAPTER 3: RESEARCH METHODS ......................................................................................15 CHAPTER 4: RESULTS ..............................................................................................................20 CHAPTER 5: DISCUSSION AND CONCLUSION ...................................................................31 BIBLIOGRAPHY .........................................................................................................................38 APPENDIX A: IRB APPROVAL DOCUMENT ........................................................................44 APPENDIX B: DISTRIBUTED SURVEY ...................................................................................45 iii CHAPTER 1: INTRODUCTION The growing disconnect between humans and nature in residential settings has led to increased interest in biophilic design (Wilson, 1984), which seeks to connect people with nature by incorporating natural elements into built environments. Recently, there has been a growing body of research highlighting the physical, psychological, and ecological benefits of biophilic design. For example, research has shown that brief interactions with nature, lasting as little as five to twenty minutes, can offer measurable cognitive and mental health benefits, including improved focus, reduced stress, and enhanced overall well-being (Browning et al., 2014; Lencastre et al., 2022; Moslehian et al., 2023; Söderlund, & Newman, 2017). Findings from multiple studies have shown that individuals exposed to views of nature, whether direct or indirect, reported lower stress levels and improved mood (Huntsman & Bulaj, 2022; Lee & Park, 2022; Li et al. 2025; Lohr et al., 1995). These findings reinforce the growing body of evidence supporting biophilic design, suggesting that even subtle integrations of nature can have profound psychological and physiological benefits in interior spaces. However, although the existing body of research on biophilic design in built environments has expanded significantly in recent years, there is lack of studies focusing on the emotional effects of biophilic design in residential environments. New research is being conducted in residential settings largely in response to increased environmental concerns and the general desire to lead a healthier life by the public. Much of the existing literature has focused on settings in workplaces, hospitals, and large residential complexes, examining how biophilic elements impact occupant well-being and satisfaction on a larger scale. Currently available literature on biophilic design primarily focuses on its emotional impact in commercial spaces and large-scale residential settings, including community living 1 centers, apartments, and hotels. It is critical to address the gap in knowledge by examining how the amount of indoor plants can affect occupant perceptions and emotional responses in residential environments. The Purpose of the Study The purpose of this study is to examine how the amount of indoor plants affect occupant emotions (i.e., pleasure and arousal), restorativeness, satisfaction, and willingness to stay in a space, with a focus on the amount of indoor plants in the residential environment. The specific objective of this study is to answer the following research questions: RQ1: How do different amounts of indoor plants (i.e., control, moderate, intense) in a residential environment affect occupants' emotions (i.e., pleasure and arousal)? RQ2: How do different amounts of indoor plants (i.e., control, moderate, intense) in a residential environment affect occupants' perception of restorativeness? RQ3: How do different amounts of indoor plants (i.e., control, moderate, intense) in a residential environment affect occupants' satisfaction? RQ4: How do different amounts of indoor plants (i.e., control, moderate, intense) in a residential environment affect occupants' willingness to stay in a space? The Significance of the Study This study will compile a comprehensive overview of the benefits associated with biophilic design, providing valuable insights that can be shared with design professionals. The findings are expected to contribute to the broader adoption of sustainable building practices that not only enhance environmental performance but also promote emotional well-being and user satisfaction. 2 This study addresses the limited research on emotional responses to biophilic design in residential spaces, which is primarily focused on workplaces and public buildings. While biophilia is known to elicit emotional responses, little research explores how varying implementation levels and specific design features influence these reactions. This study is expected to provide insights into biophilic applications in personal living spaces, enhancing understanding of their impact on emotional well-being, and explore how different levels of greenery elements impact emotions in home environments, filling a gap in understanding indoor planting’s role in private living spaces. Overview of the Following Chapters Chapter 2 is the literature review for this research paper and is composed of sections that explore the application methods and implementation rates of biophilic design features. The guiding principles of the pleasure & arousal framework and the attention restoration theory are each explored in this section due to the guided use of their questions and principles. Chapter 3 includes the research methods and applications that were used for this study. Explanation of the stimuli creation processes, participant selection, data collection process, and survey measurement methods is included. Chapter 4 begins with a description of participant demographics and continues with results from the reliability test and descriptive statistics that overview all measured variables, (pleasure, arousal, restorativeness, satisfaction, and willingness to stay in the space). The results of statistical methods including repeated measures ANOVA and Post hoc comparison are reported in this chapter. Chapter 5 presents a discussion of the discovered results that examine each of the research variables, as well as a review of the known study limitations. This section also explores 3 the implications and interpretations that were revealed and potential research topics that can fill in gaps related to emotional impacts of indoor plants. The chapter concludes with a comprehensive conclusion of the research study and its results. 4 CHAPTER 2: LITERATURE REVIEW Biophilic Design One of the first uses of the term “Biophilia” was used by psychologist Erich Fromm to describe "the passionate love of life and of all that is alive"(Fromm, 1964). This concept was later described as 'the innate tendency in human beings to focus on life and lifelike processes” (Wilson, 1984). Existing literature findings emphasize the therapeutic potential of biophilic elements in the built environment, reinforcing their role in promoting psychological well-being and recovery. How incorporating biophilia into architecture is more complex than placing plants and using greenery but instead is a more in-depth practice of manipulating the physical, sensory, and metaphorical types of nature (Zhong et al., 2022). By incorporating natural elements indoors, individuals can experience the comfort and connection benefits of nature without leaving their personal living space. While direct exposure to nature is believed to be ideal, research suggests that biophilic design extends beyond close physical proximity to plants, the potential benefits encompass a broader relationship including indirect experiences such as views of green spaces, natural materials, and biomorphic design patterns (Yassein & Ebrahiem, 2018). Previous research indicates that the amount of indoor plants in an indoor environment such as the visible greenery rate, can affect occupant experiences. According to Zhaoming et al. (2022), participants exposed to vegetative walls at an 80% implementation rate experienced the highest stress reduction (Zhaoming et al., 2022). This study demonstrates a direct correlation between biophilic incorporation rates and user experiences, aligning with similar findings on vegetation density and its psychological effects. Additionally, research suggests that vegetation rates have an inflection point near 20% (Rhee et al., 2023). Rhee et al. (2023) further found that 5 maximum benefits for stress reduction and restoration occur at vegetation implementation rates between 13% and 24%. Biophilia in Healthcare and Commercial Settings Biophilic design features have been associated with significant physical and mental health benefits across diverse global settings (Kellert & Wilson 1993; Mencer, 2023). Mencer’s (2023) review of studies documented the long-term advantages of these practices and the effects that indoor plants can have on patients' perceptions of hospital experiences. Additional research highlights the applicability of biophilic design in critical health interventions, including suicide prevention and the reduction of suicidal thoughts and feelings (Booth et al., 2023). Research indicates that individuals overwhelmingly prefer direct interactions with nature, expressing dissatisfaction with the limited availability of green spaces. This is supported by results of a study that found of 138 polled cancer center staff and patients, patients placed natural lighting, views of nature, and thermal comfort at the top of 11 chosen categories, while caregivers preferred access to private and quiet spaces (Tinner et al., 2018). These findings support the argument for higher rates of biophilic practices to be adopted in medical facilities. Studies suggest that even virtual reality environments can effectively simulate biophilic experiences, making it a valuable tool for workplaces and healthcare settings where direct access to nature may be limited. In a study comparing physical and virtual biophilic settings of an office building, Yin et al. (2018) found that participants who were exposed to natural elements had 8.6 mmHg lower systolic and 3.6 mmHg lower diastolic blood pressure. Participants demonstrated a 14% improvement in short-term memory and a reduction in negative emotions, with positive benefits being seen in participants after being exposed to both reality and virtual exposure (Yin et al., 2018). 6 Research has shown that incorporating natural elements into built environments can counteract the negative effects of non-places and increase enjoyment in workplaces. In a pioneering study, Lohr et al. (1995) found that the presence of indoor potted plants significantly reduced perceived stress levels while simultaneously enhancing occupants’ concentration and focus. This study examined the experiences of workers in windowless offices compared to those with access to natural views. Biophilia in Residential Spaces Biophilic design is a widely favored approach for fostering human-nature connections, yet it remains underutilized in residential settings. While biophilic design has been extensively studied in commercial and medical settings, its application in residential architecture remains an area of growing interest (Clark-Havron, 2023). Clark-Havron (2023) reviewed biophilic design practices in residential homes, compiling case studies from previous research to explore small scale applications. Clark-Havron’s (2023) review discusses how all of their selected studies collectively agreed that biophilia and biophilic design is important and should be emphasized further. Empirical findings support the psychological benefits of biophilic integration in residential settings. Aabouelela (2023) conducted a study of university staff and students and found that there is a relationship between negative feelings and absence of natural elements. The author emphasizes “the effectiveness of integrating biophilic design into the design of residential units to improve human mental health and well-being" (Aabouelela, 2023). The integration of greenery in residential developments has been an increasingly recognized practice that is essential for psychological well-being and sustainability. A case study examining the design of “Sinpaş Altınoran”, a residential site in Ankara, Turkey, highlights how 7 biophilic elements contribute to stress reduction, enhanced relaxation, and improved environmental quality (Kahveci & Güneş, 2020,). The goal of this study was to determine the site requirements for urban living centers and what the criteria is that determines the classification of “Biophilic Design.” Kahveci and Güneş (2020) claim that “enhanced connection can contribute to our welfare by means of minimizing stress, improving rejuvenation, thus assisting to reduce the costs and enhancing the outcomes within the built environment” (p. 127). Kahveci & Güneş determined that the large-scale development included enough environmental enhancement to meet their criteria for using structural and plant materials, with a ratio of 71% (p.150). Research on biophilic design patterns suggests that greenery enhances mood, reduces stress, and improves cognitive clarity by replicating natural landscapes. Green spaces in residential settings are widely recognized for their mental health, cognitive, and overall well- being benefits (Ryan et al., 2014). Ryan et al. (2014) state that “good biophilic design draws from nature in a manner that is equally inspirational and restorative without disturbing the functionality of the space” (p. 63), highlighting the need to balance aesthetics and function in residential greenery integration. Ryan et al.(2014), found that the presence of vegetation, dynamic lighting, and natural textures has been shown to lower cortisol levels and improve emotional stability, making biophilic interventions valuable in urban housing projects. Further research can be conducted to quantify the effects of indirect exposure to nature, such as interior green walls or framed garden views. Gaining insight into the decision-making factors behind willingness to pay can enable policymakers and developers to implement targeted strategies that balance affordability with environmental sustainability, ensuring that green infrastructure becomes a fundamental 8 component of future residential planning. The economic value of green infrastructure has become an area of growing interest. Research indicates that homebuyers are willing to pay higher prices for properties that incorporate greenery (Zalejska-Jonsson et al., 2020, p. 2). Green infrastructure provides ecological and social benefits, including improved air quality, stormwater management, and enhanced thermal insulation, contributing to both sustainability and personal comfort (Lee & Park 2021). This underscores the need for further research on consumer psychology and market preferences regarding greenery in housing developments. Emotional Responses To Biophilia Emotions and Restorativeness, Emotional and psychological impacts of the built environment are significant, with natural settings being used to promote wellbeing and reduce emotional stress and fatigue. Browning et al. (2014) emphasize that experiencing natural environments positively influences emotional states by reducing tension, anger, fatigue, and overall distress when compared to the effects of urban environments. Sayuti (2016) shows that the intersection of biophilia, emotional design, and spatial aesthetics, can extend into practices and features that are not commonly studied in the field of biophilic design. Furniture design with embedded living organisms has been studied and initial results suggest that there is a direct correlation between furniture design with living organism's (FDLO’s) and positive and negative emotional responses (Sayuti, 2016). This study assessed self-reports, physiological measurements, and behavioral observations to evaluate perceptions of biophilic furniture. Interviews and survey results from participating designers suggest that biophilia may play a role in designers' motivations as well as users' emotions and experiences (Sayuti, 2016, p. 87). 9 A review of 45 studies examining nature connections, sensory stimuli, and spatial experiences found that natural images, plant presence, visual and non-visual connections to nature, and material connection to nature are the top patterns studied when reviewing the health effects of biophilia (Hung & Chang 2021). Hung and Chang (2021) emphasize that “practical landscape and built environments can be designed to link humans and nature and reinforce biophilia in creating healthier, more restorative residential spaces Lee et al. (2015) demonstrated that university students who were shown a 40-second viewing of a green roof, attention rates were significantly increased when compared other students presented with views of a concrete roof and the baseline test. Participants who viewed the green roof made fewer omission errors and showed a more consistent response to the tasks presented compared to students who were presented with the concrete rooftop, thus providing evidence in support of restorative micro-breaks (Lee et al., 2015). Amount of Indoor Plants Research measuring emotional and neurological effects of three types of biophilic design in virtual hospital rooms using EEG and VR methods was used to make direct connections between emotions and the presented imagery. A study by Jung et al.(2023) was conducted using three different groups which were presented with hospital rooms that each had varying amounts of biophilic design elements, and found that adding plant walls can reduce negative emotions by calming the nervous system. The results from the EEG measurements provided an insight into the body’s response to different stimuli, and how tension and high arousal were lowered in comparison to images with a lower biophilic presence (Jung et al., 2023). Similar results can be found in research by Navarrete-Hernandez et al. (2024), which explored participants’ emotional states by providing one of six images that ranged from 0% to 10 45% of greenery coverage in a street view setting. It was further found that the happiness variable that was tested showed an always positive linear relationship with an increase in presented green infrastructure, with vertical green interventions being the most impactful (Navarrete-Hernandez et al., 2024). Effects of Occupant Characteristics Perceptions of biophilic design have shown some variance in previous studies based on income, gender, and personal preferences, shaping interactions with natural elements in residential spaces. A study of three Nigerian Luxury Hotels found that of 415 useful responses, age and cultural background were notable moderators, with older adults and non-Nigerian guest perceiving higher levels of restoration in some aspects (Yusuf et al., 2024). These findings suggest that biophilic design interventions should be tailored to different user demographics, ensuring accessibility and maximizing benefits across diverse residential communities. Findings indicate that higher-income participants valued natural light, stress reduction, and cognitive benefits, while lower-income participants associated biophilic features with tranquility and emotional well-being (Khanzadeh, 2024). Khanzadeh (2024) also found that males reported substantially higher mean scores than females in positive emotional responses to biophilic design elements, emphasizing gender-based differences in interior design preferences. Results also indicate that income levels may influence perceptions of biophilic design, with higher-income individuals prioritizing cognitive and productivity benefits, while lower-income participants valued emotional and sensory experiences (Khanzadeh, 2024). Satisfaction and Willingness to Stay Wichrowski et al. (2021) conducted a mixed-methods study examining the effects of biophilic imagery on patient satisfaction in a hospital rehabilitation unit and found a significant 11 increase in patient satisfaction, as well some improvement in overall quality of stay, sleep, and care. Patients assigned to rooms decorated with nature-themed curtains and wall posters rated their environments significantly higher on the chosen Environmental Assessment Scale than those in the normal rooms which were used as a control variable (Wichrowski et al., 2021). Gong et al., (2020) investigated China’s largest residential complex, where factors such as sunlight exposure and access to green spaces were critically analyzed due to the severe limitations on biophilic design implementations caused by high urban density. Findings revealed that, when compared to residents of another residential complex with greater access to greenery, individuals in settings with less greenery visible reported lower satisfaction levels and a diminished sense of well-being (Gong et al., 2020). The integration of biophilia in Dubai’s residential sector has increased recently, as noted by Skakhhshir & Sheta (2023), the UAE has focused on green building and energy efficiency, particularly across high-rise buildings, villas, and townhouses. While residents generally appreciate biophilic elements, specific biophilic elements features, such as balcony spaces and green infrastructure, received neutral to low satisfaction ratings. The study found that “occupants were highly satisfied with biophilic features in their living space (74.2%) but showed neutral to low satisfaction (42.8%) with specific features such as indoor vegetation and natural ventilation” (Shakhshir & Sheta, 2023). In a study conducted in virtual museum environments, Dalay and Aytac (2024) found that integrated natural features in exhibitions enhanced participants’ perceptions of orientation, spatial perception, and emotional responses. The researchers also found that participants generally felt more content, relaxed, and at ease, which suggests that even simulated environmental greenery can cause users to have positive spatial perceptions (Dalay & Aytac, 12 2024). Khozaei et al. (2022) found that when looking at the relationship of COVID-19 and mental states, the participants of their study that had higher levels of stress and mental burdens associated with COVID-19 reported significantly affected their preferences for nature and hotels that used biophilic attributes. The findings from these studies show that integrating natural features indoors can cause users to feel more comfortable and content, leading to a greater willingness to stay. Guiding Theories Pleasure Arousal Framework Emotional responses can be difficult to measure and may be perceived and interpreted differently between individuals, thus multiple systems have been created to classify emotional responses. Environmental stressors such as excessive noise, crowding, and pollution can have predictable negative effects on an individual’s emotional state, specifically in terms of pleasure, arousal, and dominance (Russell and Mehrabian, 1974). Mehrabian’s further research into pleasure, arousal, and dominance shows that almost all emotions can be described by participants as relating to one of the branches of the proposed model (Mehrabian, 1996). Russell & Mehrabian (1977) describes and gathered evidence from 200 subjects to support the idea of dividing emotions into three dimensions. Upon further research the pleasure scale was given affective responses with six bipolar descriptors, Happy/Unhappy, Pleased/Annoyed, Satisfied/Unsatisfied, Contented/Melancholic, Hopeful/Despairing, and Relaxed/Bored, capturing the degree of positive or negative emotional engagement with the space (Mehrabian, 1976). The arousal scale measured levels of physiological and psychological activation, utilizing descriptors such as Stimulated/Relaxed, Excited/Calm, Frenzied/Sluggish, Jittery/Dull, Wide- awake/Sleepy, and Aroused/Unaroused (Mehrabian 1976). The Dominance component of 13 Russell & Mehrabian’s (1977) framework was excluded from this study as it was determined that it was not in the scope of the research questions. Attention Restoration Theory Kaplan and Kaplan’s (1989) Attention Restoration Theory (ART) provides a useful framework for understanding the connection between environments and emotional states. According to Kaplan and Kaplan (1989), Being Away refers to the sense of mental detachment from daily stressors, allowing individuals to experience a break from routine. Soft Fascination describes elements that capture attention effortlessly, such as natural textures, greenery, or flowing water, promoting cognitive restoration without demanding focused effort. Compatibility reflects how well an environment supports an individual's needs, ensuring that the space aligns with their preferences for relaxation and well-being (Kaplan & Kaplan, 1989). 14 CHAPTER 3: RESEARCH METHODS This quantitative study employed an online survey to compare the emotional responses in individuals based on their perceptions of indoor plants in residential spaces. It examined emotional perceptions as participants view the same space with varying levels of biophilic integration. This study builds on previous studies (Fadda et al., 2023; Sayuti et al., 2015) by assessing how the amount of indoor plants impacts emotional perceptions when the visible presence of features is different. Stimuli Creation To measure the impact of indoor plants in residential environments, we designed three residential living areas with different levels of indoor plants being integrated. The image of the living room was selected after reviewing a range of living room images, in consultation with two experienced interior design professionals. The visual stimuli for this study were developed using Adobe Photoshop to create three variations of a single residential interior. The base image remains consistent across all conditions, ensuring uniformity in spatial layout, lighting, and non- biophilic furnishings (see Figure 1). Image A showed no indoor plants and did not include any greenery applications. Image B presented a moderate amount of visible greenery in the form of potted plants and living wall decor. Image C had an intense amount of greenery that filled the space with more plants, and larger living walls. All participants viewed the same rendered images of the interior space, the three coverage levels were determined by calculating the proportion of the image area visually occupied by plant material relative to the total visible surface area of the image using pixel-based measurements in the image editing software: 0% (control), 10% (moderate), and 25% (intense). 15 Image A (Control) No indoor plants Image B (Moderate) Moderate amount of indoor plants Image C (Intense) Intense amount of indoor plants Figure 1. Survey Images of Three Indoor Planting Conditions Participants Participants were recruited through convenience sampling through Michigan State University and online survey service platform Prolific. A digital survey link was distributed to students at Michigan State University’s School of Planning, Design, and Construction (SPDC), allowing them to access the study online while remaining anonymous. All SPDC participants gave their informed consent and were offered the chance to enter a raffle to receive a gift card with a $10 value in order to increase participation rates. A total of 52 responses were collected. On the Prolific platform, participants were efficiently recruited and compensated to boost data collection. Prolific filters allowed for demographic diversity, and all participants provided informed consent before beginning the study. Participants used a Qualtrics survey that presented the same survey as other recruitment methods. A total of 112 responses were collected. After removing incomplete responses, a total of 150 complete responses were used for further analysis. Data Collection Process The survey was administered through the online platform Qualtrics. A pilot test was carried out with 10 respondents to identify potential issues with the survey design and data collection process. Following the pilot test and necessary adjustments to ensure smooth data collection, the main survey was conducted. 16 Upon beginning the survey, participants were first shown Image C (intense) of the three image variations and asked to evaluate their emotional response. This process was then repeated for Image A (control) followed by Image B (moderate). ensuring that each participant viewed and assessed all three indoor planting conditions. The order of intense → control → moderate conditions was chosen to minimize expectation bias and prevent desensitization or adaptation, which could occur if the sequence started with less intense conditions and progressed to more intense ones. This approach enables a clearer understanding of how emotional responses vary across different levels of greenery. Following the image evaluations, participants completed a demographic questionnaire to collect information on age, gender, race, and academic background. Survey Measurement The survey questionnaire was developed to measure (1) emotions including pleasure and arousal, (2) restorativeness, (3) satisfaction, and (4) willingness to stay (see Table 1). Participants self-reported their responses using a 7-point Likert scale. A Likert scale was chosen due to its ability to gather participants' opinions in a more efficient format than individual questions (Batterton & Hale 2017). Emotions were measured using the pleasure and arousal scale introduced in Russell & Mehrabian’s An Approach to Environmental Psychology (1974). The pleasure scale was given affective responses with six bipolar descriptors, happy/unhappy, satisfied/unsatisfied, contented/melancholic, hopeful/despairing, and relaxed/bored, capturing the degree of positive or negative emotional engagement with the space (Mehrabian, 1976). The arousal scale measured levels of physiological and psychological activation, utilizing descriptors such as 17 stimulated/relaxed, excited/calm, frenzied/sluggish, jittery/dull, wide-awake/sleepy, and aroused/unaroused (Mehrabian, 1976). Restorativeness was measured using the perceived restorativeness scale (PRS) developed by Hartig et al. (1997), which assesses the restorative effects of natural environment. It consists of 18 items, but this study used the 6 following items: It is an escape experience; Spending time here gives me a good break from my day-to-day routine; This place has fascinating qualities; I would like to get to know this place better; I can do things I like here, and I have a sense that I belong here (Hartig et al., 1997). Satisfaction was measured using 3 items adapted from Nanu et al.(2020), which assessed satisfaction with biophilic design in hotel lobbies. The selected questions are as follows: I would be happy with the experiences I could have in this room; I would feel satisfied with the experiences I could have in this room; I would really enjoy spending time in this room (Nanu et al., 2020). Willingness to stay was evaluated using 2 items based on Nanu et al.(2020). The following items were selected due to their ability to gauge participant preference and comfort of the space: My willingness to stay in this room is high and The likelihood of me staying in this room is high (Nanu et al., 2020). Table 1. Variable Questions Variable Pleasure Number of Questions 5 Response Options Scale 7-point bipolar scale - Unhappy/ Happy - Bored/ Relaxed - Unsatisfied/ Satisfied - Melancholic/ Content - Despairing/ Hopeful 18 Table 1. (cont’d) Arousal 5 Restorativeness 6 -Relaxed/Stimulated - Calm/Excited - Sluggish/Frenzied - Dull/Jittery - Sleepy/Wide-Awake - It is an escape experience. - Spending time here gives me a good break from my day-to-day routine. - This place has fascinating qualities. - I would like to get to know this place better. - I can do things I like here. - I have a sense that I belong here. Satisfaction 3 - I would be happy with the experiences I could have in this room. - I would feel satisfied with the experiences I could have in this room. - I would really enjoy spending time in this room. Willingness to stay 2 - My willingness to stay in this room is high. - The likelihood of me staying in this room is high. 7-point bipolar scale 7-point Likert (1 = Strongly disagree, 7 = Strongly agree) 7-point Likert (1 = Strongly disagree, 7 = Strongly agree) 7-point Likert (1 = Strongly disagree, 7 = Strongly agree) 19 Participant Profile CHAPTER 4: RESULTS Participants ranged from 18 to 65+ years old, with the largest age group being 18-24 years old (n = 42, 29.4%), followed by 25-34 years old (n = 37, 25.9%). A notable portion of participants were aged 45-54 (n = 28, 19.6%), while smaller percentages were 35-44 years old (n = 19, 13.3%), 55-64 years old (n = 11, 7.7%), and 65 or older (n = 6, 4.2%). The majority of participants identified as female (n = 91, 63.6%), while n = 50 (35.0%) identified as male. The sample was predominantly Caucasian (n = 106, 70.7%), followed by African American (n = 24, 16.0%), Asian (n = 10, 6.7%), and American Indian (n = 4, 2.7%). Participants had varied levels of education, with the highest proportion having completed a four-year college degree (n = 48, 33.6%), followed by some college education (n = 39, 27.3%). Other participants had attained a graduate or professional degree (n = 19, 11.9%), an associate degree (n = 15, 10.5%) or had only completed high school (n = 20, 14.0%). Table 2. Participant Profile Age (N=143) Gender (N=143) Race (N=143) Demographics 18-24 25-34 35-44 45-54 55-64 65 or older Male Female Others Caucasian African American American Indian Asian Others 20 Frequency Percent 29.4 25.9 13.3 19.6 7.7 4.2 35 63.6 1.4 70.7 16 2.7 6.7 2 42 37 19 28 11 6 50 91 2 106 24 4 10 3 Table 2. (cont’d) Education Level (N=143) Completed high school Some college Associate degree Four-year college degree Graduate or professional degree Others 20 39 15 48 19 2 14 27.3 10.5 33.6 11.9 1.4 Reliability Test and Descriptive Statistics A reliability analysis was conducted to assess the internal consistency of survey items measuring pleasure, arousal, restorativeness, satisfaction, and willingness to stay across three indoor planting conditions (Control, Moderate, and Intense). The results showed a high reliability across all variables, with Cronbach’s alpha values ranging from .78 to .98, indicating strong internal consistency (see Table 3). For pleasure, which was measured using five items, mean ratings increased as indoor plant quantity increased. Participants reported the lowest pleasure ratings in the Control condition (M = 4.47, SD = 1.75, α = .96), with ratings increasing in the Moderate (M = 5.23, SD = 1.35, α = .95) and Intense conditions (M = 5.49, SD = 1.36, α = .93). This suggests that participants found environments with more greenery to be more pleasurable, with high reliability across all conditions (see Table 3 and Figure 2). The arousal variable, also measured using five items, exhibited slightly lower but still acceptable reliability (α = .78 – .81). Mean arousal scores were lowest in the Control condition (M = 3.28, SD = 1.13, α = .80), increased in the Moderate condition (M = 3.71, SD = 1.05, α = .81), but slightly declined in the Intense condition (M = 3.65, SD = 1.11, α = .78). This pattern suggests that moderate levels of plant presence may enhance alertness more than extreme levels. For restorativeness, measured with six items, reliability remained high across all conditions (α = .93 – .96). The Control condition had the lowest mean restorativeness rating (M 21 = 4.02, SD = 1.69, α = .96), while the Moderate condition (M = 4.75, SD = 1.42, α = .96) and Intense condition (M = 5.10, SD = 1.32, α = .93) demonstrated a steady increase, reinforcing the idea that more greenery contributes to a stronger perception of restorative benefits. The satisfaction variable, which consisted of three items, followed a similar upward trend with high internal reliability (α = .96 – .97). Satisfaction ratings were lowest in the Control condition (M = 4.33, SD = 1.70, α = .96), increased in the Moderate condition (M = 4.96, SD = 1.46, α = .97), and reached their highest in the Intense condition (M = 5.49, SD = 1.44, α = .96). Finally, willingness to stay, measured using two items, exhibited the highest reliability coefficients (α = .96 – .98). Participants reported the lowest willingness to stay in the Control condition (M = 2.75, SD = 1.29, α = .98), with a substantial increase in the Moderate condition (M = 4.89, SD = 1.58, α = .98) and Intense condition (M = 5.49, SD = 1.59, α = .96). This suggests that plant presence significantly impacts participants’ desire to remain in an environment, with more greenery leading to greater willingness to stay in the space. Table 3. Reliability Test and Descriptive Statistics Variable Pleasure Arousal Restorativeness Satisfaction Willingness to stay Number of items 5 5 6 3 2 Mean 4.47 5.23 5.49 3.28 3.71 3.65 4.02 4.75 5.10 4.33 4.96 5.49 2.75 4.89 5.49 S,D 1.75 1.35 1.36 1.13 1.05 1.11 1.69 1.42 1.32 1.70 1.46 1.44 1.29 1.58 1.59 Cronbach’s alpha .96 .95 .93 .80 .81 .78 .96 .96 .93 .96 .97 .96 .98 .98 .96 Planting Condition Control Moderate Intense Control Moderate Intense Control Moderate Intense Control Moderate Intense Control Moderate Intense 22 Figure 2. Mean Emotional Responses Across Each Planting Condition Effects of Indoor Plants on Pleasure A repeated measures ANOVA was conducted to assess the impact of three indoor plant quantity conditions on pleasure ratings. Given that Mauchly's Test of Sphericity was significant (p < .05), suggesting a violation of sphericity (see Table 4), the Greenhouse-Geisser correction was applied. The results of the repeated measures ANOVA (see Table 5) revealed significant differences in pleasure ratings across the three conditions, F(1.92, 272.59) = 44.50, p < .001, with a large effect size (partial eta squared = 0.24). Table 4. Result of Mauchly's Test of Sphericity for Pleasure Within Subjects Effect Pleasure Mauchly's W .95 Approx. Chi-Square 6.02 df 2 Sig. .049 Greenhouse- Geisser .96 Huynh- Feldt .97 Lower- bound .50 Epsilon 23 Table 5. Tests of Within-Subjects Effects for Pleasure Pleasure Error Sphericity Assumed Greenhouse- Geisser Huynh-Feldt Lower-bound Sphericity Assumed Greenhouse- Geisser Huynh-Feldt Lower-bound Sum of Squares* 85.43 df 2 Mean Square 42.71 F 45.35 Sig. <.001 Partial Eta Squared .24 85.43 1.92 44.50 45.35 <.001 85.43 85.43 267.49 1.94 1.000 284 43.91 85.43 .94 45.35 45.35 <.001 <.001 .24 .24 .24 267.49 272.59 .98 267.49 267.49 276.24 .96 142.00 1.88 Note. Greenhouse-Geisser correction was used. Type III sum of squares Post hoc comparisons using Bonferroni adjustments showed significant differences in pleasure ratings between conditions (see Table 6). Specifically, the Intense condition was rated significantly higher than both the Control (Mean Difference = 1.05, p < .001) and Moderate (Mean Difference = 0.26, p = .045) conditions. Additionally, the Moderate condition was rated significantly higher than the Control condition (Mean Difference = 0.78, p < .001). Table 6. Post hoc Test Results for Pleasure Mean (I) pleasure Control Moderate Intense (J) pleasure Moderate Intense Control Intense Control Moderate Difference (I-J) Std. Error Sig.b <.001 <.001 <.001 .045 <.001 .045 -.78* -1.05* .78* -.26* 1.05* .26* .11 .12 .11 .10 .12 .10 95% Confidence Interval for Differenceb Lower Bound Upper Bound -1.05 -1.35 .51 -.52 .74 .004 -.51 -.74 1.05 -.004 1.35 .52 Based on estimated marginal means *. The mean difference is significant at the .05 level. b. Adjustment for multiple comparisons: Bonferroni. 24 Effects of Indoor Plants on Arousal A repeated measures ANOVA was conducted to examine the effect of three indoor plant quantity conditions on arousal ratings. Given that Mauchly's Test of Sphericity was not significant (p =.101), suggesting that the assumption of sphericity was not violated (see Table 7), no correction to the degrees of freedom was necessary. The results of the repeated measures ANOVA (see Table 8) revealed a significant effect of indoor plant quantity on arousal, F(2, 284) = 13.98, p < .001, with a small effect size (partial η² = .09). This indicates that arousal significantly differed across the three indoor plant quantity conditions. Table 7. Result of Mauchly's Test of Sphericity for Arousal Within Subjects Effect Arousal Mauchly's W .96 Approx. Chi-Square 4.58 df 2 Sig. .101 Greenhouse- Geisser .96 Epsilonb Huynh- Feldt .98 Lower- bound .50 Table 8. Tests of Within-Subjects Effects for Arousal Source Arousal Error Sphericity Assumed Greenhouse-Geisser Huynh-Feldt Lower-bound Sphericity Assumed Greenhouse-Geisser Huynh-Feldt Lower-bound Sum of Squares* 15.05 15.05 15.05 15.05 152.84 152.84 152.84 152.84 df 2 1.93 1.96 1.00 284 275.20 278.94 142.00 Mean Square 7.52 7.76 7.66 15.05 .53 .55 .54 1.07 *Type III sum of squares F 13.98 13.98 13.98 13.98 Sig. <.001 <.001 <.001 <.001 Partial Eta Squared .09 .09 .09 .09 Post hoc comparisons using Bonferroni adjustments showed the Control condition was rated significantly lower than both the Moderate (Mean Difference = -0.42, p < .001) and Intense 25 (Mean Difference = -0.37, p < .001) conditions (see Table 9). However, no significant difference was found between the Moderate and Intense conditions (Mean Difference = 0.04, p = 1.000). Table 9. Post hoc Test Results for Arousal (I) Arousal Control Moderate Intense (J) Arousal Moderate Intense Control Intense Control Moderate Mean Difference (I-J) -.42* -.37* .42* .04 .37* -.04 Std. Error .083 .09 .08 .08 .09 .08 Sig.b <.001 <.001 <.001 1.000 <.001 1.000 Based on estimated marginal means *. The mean difference is significant at the .05 level. b. Adjustment for multiple comparisons: Bonferroni. Effects of Indoor Plants on Restorativeness 95% Confidence Interval for Differenceb Lower Bound Upper Bound -.62 -.59 .21 -.15 .14 -.25 -.21 -.14 .62 .25 .59 .15 A repeated measures ANOVA was conducted to assess the impact of three indoor plant quantity conditions on restorativeness ratings. Given that Mauchly's Test of Sphericity was strongly significant (p < .01), suggesting a violation of sphericity (see Table 10), the Greenhouse-Geisser correction was applied. The results of the repeated measures ANOVA (see Table 11) revealed significant differences in restorativeness ratings across the three conditions, F(1.86, 264.38) = 50.95, p < .001, with a large effect size (partial eta squared = 0.26). Table 10. Result of Mauchly's Test of Sphericity on Restorativeness Within Subjects Effect res Mauchly's W .92 Approx. Chi- Square 10.86 df 2 Sig. .004 Greenhouse- Geisser .93 Epsilonb Huynh- Feldt .94 Lower- bound .50 Table 11. Tests of Within-Subjects Effects for Restorativeness Source Sum of Squares* df Mean Square F Sig. Partial Eta Squared 26 Table 11. (cont’d) Restorative Error Sphericity Assumed Greenhouse-Geisser Huynh-Feldt Lower-bound Sphericity Assumed Greenhouse-Geisser Huynh-Feldt Lower-bound *Type III sum of squares 2 1.86 1.88 1.00 94.86 94.86 94.86 94.86 269.94 284 269.94 269.94 269.94 264.38 267.76 142.00 <.001 <.001 .26 .26 <.001 .26 <.001 .26 47.43 49.90 50.95 49.90 49.90 50.31 94.86 49.90 .95 1.02 1.00 1.90 Post hoc comparisons using Bonferroni adjustments showed significant differences in restorativeness ratings between conditions (see Table 12). Specifically, the Intense condition was rated significantly higher than both the Control (Mean Difference = 1.13, p < .001) and Moderate (Mean Difference = 0.38, p = .001) conditions. Additionally, the Moderate condition was rated significantly higher than the Control condition (Mean Difference = 0.75, p < .001). Table 12. Post hoc Test Results of Restorativeness (I) Restorativeness Control Moderate Intense (J) Restorativeness Moderate Intense Control Intense Control Moderate Mean Difference (I-J) -.75* -1.13* .75* -.38* 1.13* .38* Std. Error Sig.b .10 <.001 .13 <.001 .10 <.001 .10 .001 .13 <.001 .001 .10 Based on estimated marginal means *. The mean difference is significant at the .05 level. b. Adjustment for multiple comparisons: Bonferroni. Effects of Indoor Plants on Satisfaction 95% Confidence Interval for Differenceb Lower Bound Upper Bound -1.01 -1.44 .48 -.63 .81 .12 -.48 -.81 1.01 -.12 1.44 .63 A repeated measures ANOVA was conducted to assess the impact of three indoor plant quantity conditions on satisfaction ratings. Given that Mauchly's Test of Sphericity was strongly significant (p < .01), suggesting a violation of sphericity (see Table 13), the Greenhouse-Geisser correction was applied. The results of the repeated measures ANOVA (see Table 14) revealed 27 significant differences in satisfaction ratings across the three conditions, F(1.83, 261.01) = 52.30, p < .001, with a large effect size (partial eta squared = 0.26). Table 13. Result of Mauchly's Test of Sphericity for Satisfaction Within Subjects Effect sat Mauchly's W .91 Approx. Chi-Square 12.99 df 2 Sig. .002 Greenhouse- Geisser .91 Epsilonb Huynh- Feldt .93 Lower- bound .50 Table 14. Tests of Within-Subjects Effects for Satisfaction Source Satisf- action Sphericity Assumed Greenhouse-Geisser Huynh-Feldt Lower-bound Sphericity Assumed Greenhouse-Geisser Huynh-Feldt Lower-bound *Type III sum of squares Error F 51.30 51.30 51.30 51.30 Sig. <.001 <.001 <.001 <.001 Partial Eta Squared .26 .26 .26 .26 Sum of Squares 96.14 96.14 96.14 96.14 266.08 266.08 266.08 266.08 df 2 1.83 1.86 1.00 284 261.01 264.27 142.00 Mean Square 48.070 52.30 51.65 96.14 .937 1.01 1.00 1.87 Post hoc comparisons using Bonferroni adjustments showed significant differences in satisfaction ratings between conditions (see Table 15). Specifically, the Intense condition was rated significantly higher than both the Control (Mean Difference = 1.15, p < .001) and Moderate (Mean Difference = 0.53, p < .001) conditions. Additionally, the Moderate condition was rated significantly higher than the Control condition (Mean Difference = 0.62, p < .001). Table 15. Post hoc Test Results of Satisfaction (I) satisfaction Control Moderate (J) satisfaction Moderate Intense Control Intense Mean Difference (I-J) -.62* -1.15* .62* -.53* Std. Error .10 .13 .10 .10 Sig.b <.001 <.001 <.001 <.001 95% Confidence Interval for Differenceb Lower Bound Upper Bound -.88 -1.47 .36 -.78 -.36 -.84 .88 -.28 28 Table 15. (cont’d) Intense Control Moderate 1.15* .53* .13 .10 <.001 .84 <.001 .28 1.47 .78 Based on estimated marginal means *. The mean difference is significant at the .05 level. b. Adjustment for multiple comparisons: Bonferroni. Effects of Indoor Plants on Willingness to Stay in the Space A repeated measures ANOVA was conducted to assess the impact of three indoor plant quantity conditions on willingness to stay ratings. Given that Mauchly's Test of Sphericity was strongly significant (p < .01), suggesting a violation of sphericity (see Table 16), the Greenhouse-Geisser correction was applied. The results of the repeated measures ANOVA (see Table 17) revealed significant differences in willingness to stay ratings across the three conditions, F(1.87, 265.59) = 321.79, p < .001, with a large effect size (partial eta squared = 0.68). Table 16. Result of Mauchly's Test of Sphericity on Willingness to Stay Within Subjects Effect Willingness to stay Mauchly's W .93 Approx. Chi- Square 10.12 d f 2 Greenhou se-Geisser .93 Sig. .006 Epsilonb Huynh- Feldt .94 Lower- bound .50 Table 17. Tests of Within-Subjects Effects for Willingness to Stay Source Willingness to stay Error Sphericity Assumed Greenhouse-Geisser Huynh-Feldt Lower-bound Sphericity Assumed Greenhouse-Geisser Huynh-Feldt Lower-bound *Type III sum of squares Sum of Squares* 601.89 601.89 601.89 601.89 272.94 272.94 272.94 272.94 df 2 1.87 1.89 1.00 284 265.59 269.01 142.00 Mean Square 300.94 321.79 317.71 601.89 .96 1.02 1.01 1.92 F Sig. 313.13 <.001 313.13 <.001 313.13 <.001 313.13 <.001 Partial Eta Squared .68 .68 .68 .68 29 Post hoc comparisons using Bonferroni adjustments showed significant differences in willingness to stay ratings between conditions (see Table 18). Specifically, the Intense condition was rated significantly higher than both the Control (Mean Difference = 2.760, p < .001) and Moderate (Mean Difference = 0.605, p < .001) conditions. Additionally, the Moderate condition was rated significantly higher than the Control condition (Mean Difference = 2.155, p < .001). Table 18. Post hoc Test Results of Willingness to Stay (I) wil1ingness to stay Control Moderate Intense (J) wil1ingness to stay Moderate Intense Control Intense Control Moderate Mean Difference (I-J) -2.155* -2.760* 2.155* -.605* 2.760* .605* Std. Error Sig.b .102 <.001 .128 <.001 .102 <.001 .116 <.001 .128 <.001 .116 <.001 Based on estimated marginal means *. The mean difference is significant at the .05 level. b. Adjustment for multiple comparisons: Bonferroni. 95% Confidence Interval for Differenceb Lower Bound Upper Bound -2.402 -3.071 1.908 -.886 2.449 .324 -1.908 -2.449 2.402 -.324 3.071 .886 30 CHAPTER 5: DISCUSSION AND CONCLUSION Discussion Participants reported higher levels of pleasure as indoor plant quantities increased, with mean scores rising significantly from the Control (M = 4.47) to the Moderate (M = 5.23) and Intense (M = 5.49) conditions. The increase in pleasure reinforces previous findings by Lohr et al. (1995) and Ryan et al. (2014), which show that vegetation enhances emotional satisfaction in interior environments. These findings similarly align with Navarrete-Hernandez et al. (2024), who found that perceived happiness increased with higher levels of street greenery, and participant reports suggest an optimal effect between 35%–45% coverage. These results suggest that even small applications of plant life can positively influence emotional experiences within residential environments. Arousal levels peaked under the Moderate greenery condition (M = 3.71), slightly higher than in the Intense setting (M = 3.65). The findings reflect Yin et al. (2018), who observed emotional benefits tapering off in highly stimulating biophilic environments. This observed pattern suggests that while some greenery is energizing, large amounts do not result in a continued upward effect on physiological or attentional responses. While consistent with previous findings, Jung et al. (2023) found that biophilic elements in hospital rooms elicited a more relaxed emotional response and reduced the amount of high-frequence band data that is found in high arousal states. These findings relate to my data, as arousal was the only variable that did not consistently increase in direct correlation with the level of greenery implemented. Participants reported progressively higher levels of restorativeness in response to higher indoor plant quantities, with the highest scores in the Intense condition (M = 5.10). This finding supports the Attention Restoration Theory (Kaplan & Kaplan, 1989), which suggests that 31 exposure to natural elements supports cognitive recovery and stress reduction through visual and sensory engagement. The consistency of improvement across conditions further validates prior research by Huntsman & Bulaj (2022) and Rhee et al. (2023), which demonstrated that even moderate greenery can contribute to reduced stress and cognitive fatigue. A study by Lee at al. (2015), found that respondents perceived a higher restorative feeling when viewing a green roof city scene than when presented with a concrete roof scene that had no visible greenery, suggesting that even brief forty second views of nature can be beneficial. Participants reported significantly greater satisfaction rates in the space with Intense levels of greenery (M = 5.49), suggesting that high levels of indoor plant integration brings both emotional comfort and positive feelings of the space. These reports present the idea that dense amounts of indoor plant integration contributes significantly to environmental satisfaction and suggests that residents may evaluate green-rich spaces more favorably. Similar to Wichrowski et al. (2021), participants who were located in hospital rooms that features biophilic elements rated their perceptions of the room and overall satisfaction rates higher than the selected control rooms. This aligns with Clark-Havron’s (2023) findings that biophilic features enhance both emotional well-being and user preferences in residential interiors. Participants’ willingness to remain in the space showed the greatest increase across all variables, with scores rising from M = 2.75 in the Control condition to M = 5.49 in the Intense condition. These findings show that the amount of indoor plant features have a direct impact on spatial preference, with participants showing greater intent to stay in environments that display greater amounts of natural elements. Connections have also been made showing that participants viewing multiple simulated museum settings with biophilic elements felt more content, at ease, and joyful, which implies that viewers are more willing to stay in this space (Dalay & Aytac 32 2024). This supports previous literature that links biophilic environments to stronger spatial attachment and desirability in residential settings (Ryan et al., 2014; Zalejska-Jonsson et al., 2020). Implications This study fills a critical research gap by exploring the emotional effects of indoor plants in residential environments, an area that has been underexplored. It demonstrates that the quantity of indoor plant elements significantly influences emotions, restorativeness, satisfaction, and willingness to stay, thus advancing our understanding of how nature in the home impacts well-being. By testing the pleasure/arousal framework and the Perceived Restorative Survey (PRS), the study enhances theoretical knowledge in biophilic design, providing empirical evidence for the role of biophilic elements in promoting emotional and cognitive restoration. These findings offer valuable insights for future research and practical applications in residential design. An important implication of this study relates to the broad conversation about how current environments lack support for emotional and mental connections. Gray and Birrell (2014) describe how modern society has led individuals to spend increasing amounts of time in space classified as “non-place”, a term originally coined by novelist Wendell Berry. Their research proposes that these spaces are characterized by a lack of vitality and organic connectedness, offering little in terms of sensory engagement or emotional attachment. The proposed concept highlights the distinction between environments that foster a sense of place and belonging versus those that feel lifeless or devoid of natural value. The findings of this study suggest that the amount of indoor plants has meaningful potential to improve residential environments by positively influencing emotional responses and 33 behavioral intentions. For residential designers, this supports the idea of incorporating greenery as an intentional design strategy rather than a decorative feature. Design elements such as green walls, indoor planting, and views of nature can contribute to restorative environments that support mental and emotional well-being for occupants, which is further supported by Li et al. (2022), who found that green walls placed in indoor environments significantly reduced stress and improved mood among occupants. The recent surge of interest in biophilic design principles can largely be attributed to the challenges brought forth by the COVID-19 pandemic. This growing awareness presents an opportunity for design studios to further promote sustainable building practices that incorporate biophilic principles. Using this design practice, studios can take steps that can increase awareness of sustainable design and reduce the energy consumption of build processes while implementing biophilic design (Söderlund & Newman, 2022; Totaforti, 2020; Wijesooriya et al., 2020). During this period of extended home confinement, individuals became increasingly aware of how their home environments influenced both their mental and physical well-being. Research was conducted in response to the pandemic and documented the strong connection between human-nature interaction and residential design, reinforcing the benefits of integrating biophilic elements into homes to support overall health (Nitu et al., 2022). Study Limitations While this study provides valuable insight into the effects of indoor plant quantities and emotional perceptions, several limitations of the study should be acknowledged. This study relied on digitally manipulated images to simulate indoor environments and may not be an exact representation of the effects of a real-world setting. This limitation was mitigated by using Photoshop editing to create the images to best resemble a real indoor space. All data was 34 collected through self-reporting survey questions that allowed for selection on a scale to best accommodate for individual variability. The fixed order of presented images that were presented to participants may have introduced bias, as the images were presented to all individuals in the same sequence. To reduce potential bias while viewing the images, the presentation order was arranged as Intense, Control, and then Moderate, rather than a sequential ordering. It is recommended that future studies present the images in a random order to minimize the potential bias and order effects. Future Research Recommendations While this study provides valuable evidence on how varying levels of greenery affect emotional and behavioral responses, several areas remain open for further investigation to expand the overall scope and generalization of these findings and the application of indoor plants in residential settings. First, future research should explore the multisensory dimensions of biophilic design and the role of indoor plantings. While this study focused solely on visual greenery, previous studies have shown that integrating sound, scent, and tactile elements can enhance emotional and cognitive outcomes (Aristizabal et al., 2021; Joye et al., 2013). Exploring multisensory environments may offer a more contextually grounded understanding of how biophilic features influence emotional experiences within residential settings. Additionally, future studies should incorporate physiological and behavioral measures alongside self-report scales to increase result reliability and accuracy. Biometrics such as heart rate variability, skin conductance, and cortisol levels can offer objective insight into emotional states and reduce bias in subjective reporting by participants (Yin et al., 2018; Van den Berg et al., 2015). 35 Previous research has shown that other variables such as age, gender, upbringing, and regional background can significantly shape perceptions of biophilic elements and preferences for spatial environments (Khanzadeh, 2024). This emphasizes that results may be influenced not only by biophilic design features, but also by demographic and cultural factors specific to a given community and should be studied further to understand the differences. Long term research will also be needed to assess how ongoing exposure to various greenery rates impacts well-being over time. Emotional responses may shift or deepen with repeated interaction, and methods such as diary-based tracking or repeated-measures designs could help capture these changes as they unfold (Barbiero et al., 2021; Kaplan & Kaplan, 1989). Conclusion The primary goal of this study was to explore how Control, Moderate, and Intense amounts of indoor plant applications affect participant perceptions of pleasure, arousal, restorativeness, satisfaction, and behavior intentions. The first research question that was looked at to be answered was how do different amounts of indoor plants (i.e., control, moderate, intense) in a residential environment affect occupants' emotions? Responses showed that pleasure increased as greenery rates increased, with participants rating the Intense condition highest. Arousal peaked at the Moderate condition before slightly declining under Intense greenery. This suggests that while emotional comfort continues to rise with more visible greenery, there may be an optimal range for perceived emotional benefits. The second question to answer is how do different amounts of indoor plants (i.e., control, moderate, intense) in a residential environment affect occupants' perception of restorativeness? Participants reported higher levels of restorativeness in environments with a larger greenery 36 presence, with the intense condition receiving the highest ratings, thus supporting theories of cognitive recovery and attention restoration through exposure to natural elements. Thirdly, this research looks at how do different amounts of indoor plants (i.e., control, moderate, intense) in a residential environment affect occupants' satisfaction? Similar to the other research question trends, satisfaction scores improved steadily across all three greenery levels, with the most favorable responses being seen in the Intense image. This suggests that intense applications contribute to occupants’ perception of the space’s quality and desirability. The final question to be answered is how do different amounts of indoor plants (i.e., control, moderate, intense) in a residential environment affect occupants' willingness to stay in a space? Willingness to stay displayed the largest increase in participant ratings of all measured variables, with ratings more than doubling from the Control to the Intense condition. This suggests a strong behavioral correlation towards biophilic features, and that participants express a clear preference for the Moderate and Intense conditions. As residential design practices continue to evolve in response to occupant health, sustainability, and user-centered values, the integration of indoor plants into living spaces offers users the potential to deepen their emotional connection and ease within the home environment. 37 BIBLIOGRAPHY Aabouelela, A. (2023). 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Physiological and psychological effects of exposure to different types and numbers of biophilic vegetable walls in small spaces. Building and Environment, 225. 109645. 10.1016/j.buildenv.2022.109645. 42 Zhong, W., Schröder, T., & Bekkering, J. (2022). Biophilic design in architecture and its contributions to health, well-being, and sustainability: A critical review. Frontiers of Architectural Research, 11(1), 114–141. https://doi.org/10.1016/j.foar.2021.07.006 43 APPENDIX A: IRB APPROVAL DOCUMENT Figure 3. IRB Approval Document 44 APPENDIX B: DISTRIBUTED SURVEY Figure 4. Distributed Survey 45 Figure 4. (cont’d) 46 Figure 4. (cont’d) 47 Figure 4. (cont’d) 48 Figure 4. (cont’d) 49 Figure 4. (cont’d) 50 Figure 4. (cont’d) 51 Figure 4. (cont’d) 52 Figure 4. (cont’d) 53