Implicit Semantic Role of Material on the Quality of Living Space Using Semantic Differential Technique

Abstract

Living spaces have been recognized as one of the functional spaces of housing. Materials and textures are regarded as some of the features of the space. The present study sought to analyze the components of the different materials (brick, stone, glass, metal, concrete, and wood) and their semantic role in living spaces. The materials’ characteristics were coded and then semantic differentials was conducted to quantify the measurement. The significant factors of materials were defined as acceptability, motivative, capability, and resistance for brick; persistence, admiration, and purity for concrete; creativeness, resilience, and capacity for wood; fatigue and limpidity for glass; strength and durability for stone; and minimal and interweaving for metal. The results of the present study indicated that the implicit meaning of acceptability in brick was based on nostalgia, traditionality, and warmth. Furthermore, the industriality, modernity, coldness, and artificiality of concrete represented the explicitness and transparency and the industriality of glass indicated limpidity. The resilience of wood was based on stagnation, strength, and solitude. Finally, the rigidity, beauty, and coldness of stone indicated the power and strength, while simplicity, solitude, and stress-induced demonstrated the tangle of metal that can affect the application and achievement of desired living space.

Keywords

interior architecture materials emotions living space semantic differential

Introduction

The effect of the surrounding environment on different individuals varies depending on how they perceive the environment. Norenzayan and Heine (2005) found that psychological phenomena could be universal or nonuniversal. There has been prior studies on the importance of context in human–environment interactions (Gifford, 2014). According to Owe et al. (2013), individuals’ beliefs about the significance of context in understanding people differs cross-culturally. It has also demonstrated that the cultural milieu affects the physical reality of spaces. With this viewpoint, scholars can examine whether psychological processes regarding people’s interactions with their settings vary or not across culturally diverse populations (Tam & Milfont, 2020). Housing as one of the environments in which human spends most of their time includes several spaces by respecting the individuals’ needs. Living space is considered one of the most important spaces. Based on the experiences, the surrounding visual environment can influence individuals’ moods and behavior (S. Kunishima et al., 2005). Architects pay more attention to the aspects related to the concept of structural implementation and functional needs during the selection of materials (Fernandez, 2012; Hegger et al., 2008) and less attention to emotions and their effectiveness during their application. Considering observations, designers choose materials based on their experiences (Ashby & Johnson, 2014; Pallasmaa, 2012). The role related to the sensory aspects of materials begins by considering the action and interaction between materials and the user (Lederman et al., 1985).

The present study aimed to attain the architectural design solutions for the desired living space linking with the internal spirits of residents. Accordingly, the choice of the appropriate materials based on the individual spirit for the wall of living space was identified as important, and was consequently assessed. The three components of sensory, physical, and functional features were obtained for space, elements, and materials using the grounded theory method. Then, the components were converted to trait pairs through semantic differential technique and the estimation of these trait pairs were separately considered for each kind of material.

Literature Review

The term “interior architecture” emerged as a discipline that applies the history of architecture and architectural theory for design and creation of interior space in the 1970s. It is regarded as an activity to define space, create the effects and produce well-being through manipulation of three-dimensional space and using the sensory stimuli of sound, touch, smell, and sight as main parts of the interior experience (Coles & House, 2007).

Interior design includes the selection of interior elements and their syntax within spatial enclosure to fulfill specific aesthetic and practical needs. The syntax of elements in the space involves the action of construction patterns (Ching & Binggeli, 2018). Shaterian (2010) defined interior design as a set of actions to optimize or change the interior space of the building with respect to structure, the syntax of elements, light, and color. Interior architect deals with the details of the human living space at a more accurate level compared to that architect. In fact, interior architecture has brought life into the living space (Kasraei, 2009).

According to Ando (1997), good architecture is not just about primary functions. Architects must also consider secondary and tertiary functions, and even beyond that. The space is considered a place for many senses including sight, sound, touch, and the unaccountable things that occur in between. The selection of materials in architecture fulfills more than one purpose. During the material selection process for an architecture project, the material’s appearance and sensory behavior play a significant role in design, while also meeting technical requirements (Malnar & Vodvarka, 2004). Architects take into account aspects related to user’s experience or sensorial stimulation such as color or visual texture during the materials selection process, along with assessing the performance aspects such as the material’s durability and compression strength (Wastiels et al., 2007).

Soliman (2013) studied the different aspects that relate to material selection and the perception levels of the material as a standard for the spaces. Also, the material’s role in the building has been addressed, and assessed the perception levels of materials such as form (aesthetic), functional, interactive virtual, and non-perception level. The building material is classified into natural such as wood and leather, composite such as concrete and clay, and fabricated materials such as metals (steel, aluminum, copper, and bronze), glass, brick, ceramic, refractories, plastics, and paints. Due to the common orientation related to environmental sustainability and scarcity of natural resources, scholars resorted to the composite and fabricated interior materials giving an impression of natural ones.

In a survey study, Nyrud and Bringslimark (2010) extracted the features of interior space that result in protecting the health of users. Previous studies have focused on preferences toward natural and non-natural materials in the indoor environment and possible health benefits (Guo et al., 2002; Ikei et al., 2017). The respondents in Austria, Finland, Canada, Norway, and Sweden were asked to give their opinion of the materials. For example, wood often was perceived as warm and environment friendly. Another group believed that public buildings could be modern and minimal, while housing could be warm and cozy.

A group of experts focused on the functional aspects of interior materials and indicated that these materials induced less warmth. Wood possesses some tactile properties in indoor environments. For the purpose of this study, the components such as color, light, material, texture, form, pattern, attention, perspective, beauty, memory, age, and gender have been extracted from the related studies (Table 1).

Table 1.

Components Mentioned in the Related Studies.

Scholars	Color	Light	Material	Texture	Form	Pattern	Attention	Perspective	Beauty	Memory	Age	Gender
M. Kunishima (1983)	*
Kuller (1986)	*		*			*
Kobayashi and Sato (1992)			*
Jaimes et al. (2001)						*	*
Cupchik et al. (2003)			*				*
Tsunetsugu et al. (2002)	*
Wierenga et al. (2004)								*
S. Kunishima et al. (2005)			*
Tsunetsugu et al. (2005)			*
Sternberg and Wilson (2006)
Yildirim et al. (2007)	*										*	*
Boubekri (2008)		*
Kirk et al. (2009)									*
Anthes (2009)		*						*
Proverbio et al. (2009)								*				*
Barrett (2010)	*	*
Shapley and Hawken (2011)	*
Amir et al. (2011)					*
Di Dio et al. (2011)									*
Foulsham et al. (2011)								*
Arsenault et al. (2012)	*	*
Wastiels et al. (2012)	*		*	*
Martínez-Soto et al. (2013)								*
Dougherty and Arbib (2013)		*
Sivaji et al. (2013)	*	*
Fich et al. (2014)					*
Momtaz and Daliri (2016)						*
Tang et al. (2017)								*
Radvansky et al. (2011); Radvansky and Zacks (2017)										*

Methodology

The grounded theory (Glaser & Strauss, 2017) has been used as a general theory in the first step of the study. This theory is related to the previous research mode and considered an inductive and exploratory research method that could allow the researcher to theory building. Scholars have used grounded theory to analyze qualitative data from interviews in different disciplines and professions (Bryant & Charmaz, 2007; Yamazaki et al., 2009). An extremely large number of studies (Boddy, 2016; Dworkin, 2012; Sandelowski, 1995) have demonstrated that from 5 to 50 respondents is the minimum sample size required to reach saturation (Mason, 2010) in grounded theory studies that use in-depth interviews. Regarding the first step of the present study, three different spaces with various materials were provided to 10 accredited specialists’ in Housing Architecture. The interior materials were presented to the interviewees in random order by computer (Figure 1). They were involved in the housing development process and interior design of housing. For the recruitment of interviewees, the invitation letter was initially sent by email to the potential participant on the basis of their respective areas of expertise. They were also told that the interview aimed to know their opinions about the interior design of their housing. In this regard, all participants recruited were local or native to the culture. Furthermore, the interviewees were unaware of the main study objectives to avoid specific conflicts during interviews.

Figure 1.

Different types of materials used for living spaces.

The interviews were transcribed and coded in terms of open, axial, and selective coding using the grounded theory. The results of the first interview were taken as a database consisting of the trait pairs of materials to 36 experts in the second step. These trait pairs were studied through semantic differential technique. This technique was developed based on the association of meanings, in which a stimulus such as the term “metal-concrete” is provided to the subject for assessing based on the bipolar features such as warmth-coldness and modernity-nostalgia and specifying what relationship can exist between stimulus and opposite features (Rafipour, 2019). Considering the level of participants’ understanding of the implicit and explicit meanings of terms, they selected their opinion for each material based on the initial assumption of the test for scoring, and finally mean was calculated. The data were evaluated by SPSS software, significant factors were specified and their relation was assessed. For each factor, the suggested categorical groupings involving its explicit and implicit concepts were obtained using experts’ opinions.

The semantic differential technique (Osgood et al., 1957) is considered the most common method to measure emotion and was used as an accurate and appropriate technique in psychological evaluation. Based on the suggestion, classifying words in the form of the traits placed along with each other determines an individual’s specific attitudes (Koleini Mamaghani & Khorram, 2008). The selected traits contain a set of semantic features of the topic under study to identify the main points. Semantic differential technique was developed to measure the emotional content of a word.

The scale describes the reaction of individuals to a concept and is constructed as a bipolar scale dealing with the sum of the scores related to each concept. In fact, it is also based on determining the degree of similarity between two concepts with respect to individual opinions. It has provided useful information regarding the individual’s attitude toward the concept. The scale development process can begin with the selection of the concept related to the study, while they are sensitive to the similarities and differences of the study group.

To attain the objective of the study, the trait pairs were selected for testing. Finally, the opposite traits were placed at the ends of the scale of intensity without any special arrangement among them.

These traits were assessed on an 11-point scale, scoring from 0 to 10. The mean of each feature is calculated after the end of the response period. Transforming qualitative concepts into quantitative values is considered one of its advantages. The semantic differential scale of material characteristics was coded into 14 categories. This type of rating scale can increase the accuracy of judgment.

The six materials of glass, concrete, stone, brick, wood, and metal were assessed in the present study. The characteristics were commonly defined for these materials and divided into opposite pairs. Further, the prepared instrument was sent to 36 experts in housing architecture and interior design through pre-existing contacts. The experts were the faculty members at the School of Architecture and Environmental Design. The possible cultural limitation of the sample was discussed by experts. There was a thoughtful argument for possible cultural and contextual factors. Samples of experts are usually nationally-representative.

Results

In the first step, a set of codes was obtained using the grounded theory and during the process of open coding, the codes from the interviews were sorted into categories. They were based on the same concepts. A phase of axial and selective coding led to the identification of new concepts. Finally, the three main categories, including sensory features, function, and form, were outlined for elements, space, and materials (Tables 2, 3 and 4).

Table 2.

Opinions About Materials and Their Coding Regarding Sensory Features.

Component	Open coding	Axial coding	Selective coding
Space	Feeling happy	Emotion	Sensory features
	At the same time, I feel the tranquility
	Feeling power
	Feeling happy
	Sense of being familiarity
	Cozy space
	Comfort and tranquility
	Feeling sleep
	Feeling attachment
	Feeling intimacy
	Feeling neutral
	It makes warm
	Brick has the sense of inviting
	I feel more tranquility
	I feel tranquility
	It fails to make the sense of quiet
	Feeling stylish
	Human gets tired in this space long termly
	Human is devoid of the sense of being alien when he enters into space for the first time
	This space makes feeling comfort
	Feeling tranquility due to belonging
	No feeling happy
	Feeling light
	Feeling simplicity and stylish
	I am devoid of stress in this space
	Space is uniform
	Space makes feeling tranquility although it is uniform
	Concrete materials are partly cold for use in residential spaces
	Materials and color result in warming the space more	Emotion-temperature
	Space is warm due to the wood color and its darkness
	Space is cold due to the presence of stone and concrete
	Space is cold due to color and stone
	Feeling coldness
	First, it makes feeling cold, and then warmth	Emotion-temperature-contrast
	Vertical light is used and makes feeling curiosity	Emotion-light
	Feeling modernity	Emotion-architectural style
	Partly cold and modern	Emotion-architectural style
	Feeling warmth, movement, and crowd	Emotion-movement and quietness
	Quietness without bustle	Emotion-movement and quietness
	Feeling quietness and ice	Emotion-movement and quietness-temperature
Elements	Details have made the space beautiful and results in feeling warm	Emotion
	Feeling belonging due to the use of frame
	It makes tranquility due to white walls
	The floor is cold since it is created of stone
	The color of the floor, wall, and roof are the same and it fails to make a good feeling	Combination-synchronicity
Materials	Brick has the sense of inviting	Emotion
	Brick has made feeling tranquility
	Parquet is better since it results in increasing intimacy and warmth
	Wood makes feeling intimacy
	The brick above the fireplace makes feeling good
	Feeling tranquility due to colors
	Brick makes feeling warm	Emotion-temperature
	Brick has warm tones
	The brick is used above the fireplace and increases the warmth
	Warm color is needed for completing	Emotion-contrast
	It has warmth and movement due to the use of brick	Feeling-movement and quietness
	Brick induces a sense of comfort	Emotion-feature
	Brick makes the space familiar and intimate	Emotion-feature
	I like to touch a brick wall	Emotion-five senses
	The combination of materials is interesting	Combination-synchronicity
	The variety of materials on the wall is good
	Brick has crowded the space a bit
	Compositing materials and their color are good for the living space
	The opposite materials have focused	Combination-companionship-contrast
	The opposition between materials and color makes the space more attractive	Combination-companionship-contrast
	I prefer to combine wood with concrete	Companionship
	I preferred a spicy color	Contrast

Table 3.

Opinions About Materials and Their Coding Regarding Form.

Component	Open coding	Axial coding	Selective coding
Space	It is very minimal	Architectural style	Form
	It is modern and solitude	Architectural style-time
	It is simple and modern. It is soulless, it is solitude	Architectural style-time
Elements	It is modern due to furniture and syntax
Elements	Vertical lines on the wall induce strength	Strength-sustainability
Materials	It is modern due to the materials	Architectural style-time
	Stone materials are more durable	Strength-sustainability
	The hardness of materials and flexibility	Strength-flexibility
	It is traditional due to the use of brick	Architectural style
	The texture is well observed in brick	Texture

Table 4.

Opinions About Materials and Their Coding Regarding Function.

Component	Open coding	Axial coding	Selecive coding
Space	I think that it is better for more temporary areas such as the lobby	Function	Function
	This space makes the sense of a lobby instead of a residential one	Function-emotion
	It induces the sense of house in human
	You cannot get used to this space
	Space is bright and cheerful	Dimensions-scale
	It does not induce a feeling of suffocation	Dimensions-scale
	Transparency makes it more modern	Visual-architectural style
	It is bright and has light	Visual-light
	It has flexibility due to open space	Visual-flexibility
	It induces the sense of strength and weightiness to space	Weight-strength
	The space is bright, cheerful, and big	Size
	It looks expensive	Economic
	It makes the sense of security	Security
	It doubles the cleanliness of the space	Visual
	It induces feeling rich	Economic-emotion
Elements	White wall has created a lot of space	Quantity-scale
Materials	A stone without reflection from floor is not good	Function
	Materials have affected the function of the space
	The material of wallpaper makes feeling more private. It is more residential
	Combining materials and lighting makes the space more practical
	It is flexible due to the use of glass	Visual-flexibility
	Using wood in the house is regarded as good although it makes the space smaller	Dimensions-emotion
	White stone has a reflection	Light-color

Three categories were generally discussed for materials qualitatively in the previous section. In the second step, the components were quantified by the semantic differential method. In this regard, all features of materials were first extracted, grouped as opposite pairs, and finalized through Delphi rounds. Further, the significant factors of each material were tested, the relationships between features were recorded, and the significant factors related to each of the six materials were identified. It is worth noting that items having a factor loading of more than 0.60 were considered significant and each factor should have at least three variables with a factor loading of more than 0.40. For sample adequacy, the Kaiser-Meier-Olkin (KMO) coefficient was calculated as well as Bartlett’s test of sphericity. As the KMO coefficient was 0.78 and χ² value was p < .05, it was decided that the factor analysis could be conducted.

Regarding brick, the five factors were generated by the factor analysis, among which four factors were retained. The first factor involved nostalgia/modernity, traditionality/industriality, and a sense of warmth/coldness. Beauty/ugliness, stagnation/dynamism, and opacity/transparency comprised the second factor, while the third factor was not formed. The fourth factor included simplicity/complexity, rigidity/flexibility, and tranquilizer/stress-induced. Finally, roughness/smoothness, weightiness/lightness, and strength/frangibility formed the fifth factor (Table 5).

Table 5.

The Factor Analysis Results of the Brick’s Characteristics.

	Component
	1	2	3	4	5
Modernity-nostalgia	0.845	0.117	−0.066	0.086	0.057
Industriality-traditionality	0.819	0.138	−0.087	−0.175	0.220
Coldness-warmth	0.668	0.170	−0.528	−0.217	−0.009
Beauty- ugliness	−0.061	0.793	0.110	0.026	−0.195
Dynamism-stagnation	0.102	−0.650	0.110	−0.257	0.51
Transparency-opacity	−0.309	0.571	0.154	−0.367	0.372
Solitude-crowd	−0.104	−0.095	0.846	0.030	−0.091
Artificiality-naturalness	−0.375	0.418	0.573	0.203	0.078
Flexibility-rigidity	−0.218	0.102	0.094	0.842	0.028
Complexity-simplicity	0.245	0.106	0.541	0.603	−0.151
Tranquilizer/stress-induced	−0.449	0.407	0.052	0.468	0.022
Roughness-smoothness	0.255	−0.265	−0.154	−0.210	0.796
Weightiness-lightness	0.520	0.189	0.317	−0.209	−0.557
Strength-frangibility	0.311	0.366	0.210	0.245	0.536
Brick	Acceptability	Motivative	Factor 3	Capability	Resistance
16 rotations	Modernity/nostalgia	Beauty/ugliness	It was not formed	Flexibility/rigidity	Roughness/smoothness
	Industriality/traditionality	Dynamism/stagnation		Complexity/simplicity	Weightiness/lightness
	Coldness/warmth	Transparency/opacity		Tranquilizer/stress-induced	Strength/frangibility

Brick possessed four features: acceptability, motivative, capability, and resistance. Nostalgia (3.56), traditionality (3.06), and warmth (2.59) represented acceptability. The motivative of brick was based on the beauty (2.96), stagnation (7.96), and opacity (1.48). Rigidity (5.85), simplicity (7.19), and tranquilizer (2.81) indicated the capability of brick, and the resistance was based on roughness (3.04), weightiness (3.70), and strength (2.76).

Regarding concrete, the three factors were generated by the factor analysis. The first factor that was very similar to that of brick involved the components of artificiality/naturalness, modernity/nostalgia, coldness/warmth, and industriality/traditionality. Additionally, the components of rigidity/flexibility, smoothness/roughness, and strength/frangibility formed the second factor. Finally, the fifth factor included the components of beauty/ugliness, tranquilizer/stress-induced, and lightness/weightiness (Table 6).

Table 6.

The Factor Analysis Results of the Concrete’s Characteristics.

	Component
	1	2	3	4	5
Industriality-traditionality	0.896	0.083	−0.088	0.133	0.118
Modernity-nostalgia	0.884	−0.110	0.157	0.011	−0.014
Coldness-warmth	0.809	0.199	0.087	−0.325	−0.178
Artificiality-naturalness	−0.591	0.159	−0.006	−0.335	0.478
Flexibility-rigidity	−0.092	0.799	0.121	−0.120	0.166
Roughness-smoothness	0.189	0.737	−0.450	0.043	0.213
Strength-frangibility	0.047	0.667	0.102	0.076	−0.057
Complexity-simplicity	0.045	0.293	0.849	0.182	−0.254
Solitude-crowd	0.291	−0.223	0.733	−0.060	0.033
Dynamism-stagnation	−0.054	0.147	0.114	0.897	−0.079
Transparency-opacity	−0.068	0.448	0.487	−0.590	−0.124
Beauty-ugliness	0.024	0.419	−0.180	0.010	0.686
Tranquilizer-stress-induced	−0.243	−0.077	−0.445	−0.044	0.534
Weightiness-lightness	0.289	−0.407	0.265	0.431	0.482
Concrete	Purity	Persistence	Factor 3	Factor 4	Admiration
8 rotations	Industriality/traditionality	Flexibility/rigidity	It was not formed		Beauty/ugliness
	Modernity/nostalgia	Roughness/smoothness			Tranquilizer/stress-induced
	Coldness/warmth	Strength/frangibility			Weightiness/lightness
	Artificiality/naturalness

Purity, persistence, and admiration were regarded as the features of concrete. Industriality (8.83), modernity (8.72), coldness (8.22), and artificiality (7.63) represented explicitness, Persistence was based on rigidity (8.48), roughness (3.52), strength (1.56), beauty (3.46), stress-induced (5.09), and weightiness (2.17) referred to admiration.

The factor analysis produced three significant factors for wood. The first factor included the components of stagnation/dynamism, strength/frangibility, and solitude/crowd. The second and third factors were not generated. Further, traditionality/industriality, simplicity/complexity, and nostalgia/modernity formed the fourth factor. The fifth factor involved roughness/smoothness, beauty/ugliness, flexibility/rigidity, and lightness/weightiness. Furthermore, the sixth factor was not formed (Table 7).

Table 7.

The Factor Analysis Results of the Wood’s Characteristics.

	Component
	1	2	3	4	5	6
Dynamism-stagnation	−0.909	−0.022	−0.094	0.004	0.000	0.032
Strength-frangibility	0.709	0.270	0.036	0.056	0.243	0.138
Solitude-crowd	0.651	0.445	−0.298	0.151	−0.208	0.164
Coldness-warmth	0.095	0.839	−0.208	0.224	−0.137	0.048
Transparency-opacity	0.021	0.785	0.138	−0.175	0.252	−0.092
Artificiality-naturalness	0.008	0.096	0.905	−0.005	−0.054	0.031
Tranquilizer/stress-induced	0.016	−0.252	0.696	0.002	0.252	0.158
Industriality-traditionality	0.000	0.118	0.009	0.846	−0.019	0.000
Complexity-simplicity	0.285	−0.290	−0.058	0.774	−0.073	−0.105
Modernity-nostalgia	−0.424	0.301	0.024	0.559	−0.083	0.379
Roughness-smoothness	0.140	0.212	0.222	−0.151	0.821	0.065
Beauty-ugliness	0.022	0.241	0.580	−0.051	−0.650	−0.107
Flexibility-rigidity	−0.018	0.057	0.047	0.116	0.327	0.746
Weightiness-lightness	0.289	0.226	−0.133	0.230	0.327	−0.683
Wood	Resilience	Factor 2	Factor 3	Creativeness	Capacity	Factor 6
11 rotations	Stagnation/dynamism	It was not formed		Industriality/traditionality	Smoothness/roughness	It was not formed
	Strength/frangibility			Simplicity/complexity	Beauty/ugliness
	Solitude/crowd			Modernity/nostalgia	Flexibility/rigidity
	Solitude/crowd			Modernity/nostalgia	Weightiness/lightness

The three factors of resilience, creativeness, and capacity were labeled for wood. The resilience of wood was based on stagnation (6.17), strength (3.72), and solitude (6.50). Traditionality (3.52), simplicity (7.22), and nostalgia (4.59) represented the factor of creativeness and finally, roughness (4.46), beauty (2.22), flexibility (4.85), and lightness (7.65) indicated the capacity of wood.

In the case of metal, two factors were constructed. According to Table 8, the first factor consists of three items, that is, simplicity/complexity, solitude/crowd, and stress-induced/tranquilizer. The second factor included modernity/nostalgia, industriality/traditionality, and coldness/warmth, while factors 3, 4, 5, and 6 were not significant.

Table 8.

The Factor Analysis Results of the Metal’s Characteristics.

	Component
	1	2	3	4	5	6
Solitude-crowd	0.921	0.052	0.061	−0.002	0.073	−0.083
Complexity-simplicity	0.831	−0.063	0.085	−0.224	0.281	−0.023
Tranquilizer/stress-induced	−0.714	−0.090	−0.214	−0.138	0.378	−0.284
Modernity-nostalgia	−0.107	0.940	−0.033	0.036	0.057	0.080
Industriality-traditionality	−0.012	0.843	0.086	−0.317	0.124	−0.087
Coldness-warmth	0.436	0.769	−0.066	−0.143	−0.197	0.050
Roughness-smoothness	−0.423	0.474	−0.154	0.281	0.344	0.348
Dynamism-stagnation	0.018	−0.110	0.817	0.171	0.029	−0.204
Weightiness-lightness	0.342	0.111	0.709	−0.048	0.019	0.063
Artificiality-naturalness	−0.190	−0.319	0.268	0.801	−0.121	−0.021
Transparency-opacity	0.137	0.051	−0.586	0.641	0.329	0.060
Beauty-ugliness	0.104	0.056	0.017	−0.028	0.924	0.159
Strength-frangibility	−0.021	−0.045	−0.125	0.110	0.073	0.826
Flexibility-rigidity	0.072	0.144	0.005	−0.446	0.128	0.601
Metal	Interweaving	Minimal	Factor 3	Factor 4	Factor 5	Factor 6
10 rotations	Simplicity-complexity	Modernity-nostalgia	It was not formed
	Solitude-crowd	Industriality-traditionality
	Solitude-crowd	Smoothness-roughness
	Tranquilizer/ stress-induced	Coldness-warmth

For metal, minimal and interweaving were labeled as two factors. Simplicity (6.96), solitude (6.67), and stress-induced (7.41) represented the interweaving of metal and the minimal was based on modernity (9.30), industriality (9.41), smoothness (7.04), and coldness (9.22).

Two significant factors were identified for the stone. The first factor included rigidity/flexibility, beauty/ugliness, and coldness/warmth, as well as strength/frangibility, roughness/smoothness, and stagnation/dynamism formed the second factor, while other factors were not statistically significant (Table 9).

Table 9.

The Factor Analysis Results of the Stone’s Characteristics.

	Component
	1	2	3	4	5	6
Flexibility-rigidity	0.884	−0.131	−0.046	0.020	−0.096	0.206
Beauty-ugliness	0.681	0.450	0.063	0.284	0.115	−0.233
Coldness-warmth	−0.641	0.047	0.482	0.069	−0.120	−0.244
Strength-frangibility	0.134	0.847	0.138	−0.104	−0.072	−0.206
Roughness-smoothness	−0.192	0.820	0.115	0.204	0.077	0.385
Dynamism-stagnation	0.142	0.457	−0.437	−0.411	−0.197	0.050
Industriality-traditionality	0.050	0.151	0.888	−0.260	0.030	0.000
Modernity-nostalgia	−0.388	0.063	0.641	0.125	0.348	−0.031
Artificiality-naturalness	0.014	0.080	−0.130	0.916	0.049	−0.027
Tranquilizer/stress-induced	0.494	0.021	−0.044	0.653	−0.500	−0.020
Complexity-simplicity	0.124	−0.216	0.020	−0.122	0.845	−0.008
Weightiness-lightness	−0.133	0.294	0.064	0.109	0.543	0.222
Solitude-crowd	0.237	−0.150	−0.126	−0.030	0.255	0.828
Transparency-opacity	−0.036	0.304	0.586	−0.062	−0.274	0.651
Stone	Strength	Durability	Factor 3	Factor 4	Factor 5	Factor 6
11 rotations	Flexibility/rigidity	Strength/frangibility	It was not formed
	Beauty/ugliness	Smoothness/roughness
	Coldness/warmth	Stagnation/dynamism

The power of stone was based on rigidity (9.28), beauty (3.74), and coldness (7.35). Additionally, strength (2.67), roughness (4.81), and stagnation (8.48) represented durability.

According to Table 10, two factors were formed for glass. The first factor involved smoothness/roughness, transparency/opacity, and industriality/traditionality and the second one was tranquilizer/ stress-induced, solitude/crowd, rigidity/flexibility, and strength/frangibility. Further, factors 3, 4, 5, and 6 were not constructed.

Table 10.

The Factor Analysis Results of the Glass’s Characteristics.

	Component
	1	2	3	4	5	6
Roughness-smoothness	0.774	0.141	−0.046	0.105	0.081	−0.068
Transparency-opacity	0.668	0.076	0.148	0.043	0.105	0.171
Industriality-traditionality	0.630	−0.144	−0.326	−0.390	−0.277	−0.003
Tranquilizer/stress-induced	−0.100	−0.848	−0.022	0.075	0.087	0.253
Solitude-crowd	−0.468	0.627	−0.375	0.134	0.058	0.377
Flexibility-rigidity	−0.153	−0.626	0.146	−0.239	0.278	0.210
Strength-frangibility	0.309	0.456	0.159	−0.395	0.341	0.269
Coldness-warmth	−0.138	0.050	0.872	−0.133	−0.095	0.078
Complexity-simplicity	−0.237	0.329	−0.681	−0.132	0.050	0.170
Artificiality-naturalness	−0.041	0.162	−0.089	0.839	0.033	−0.165
Beauty-ugliness	0.427	−0.273	0.091	0.640	−0.069	0.324
Dynamism-stagnation	−0.129	0.147	0.205	−0.024	−0.775	0.229
Modernity-nostalgia	−0.022	−0.039	0.021	−0.010	0.730	0.163
Weightiness-lightness	−0.091	0.211	0.030	0.082	−0.012	−0.845
Glass	Limpidity	Fatigue	Factor 3	Factor 4	Factor 5	Factor 6
11 rotations	Smoothness/roughness	Tranquilizer/stress-induced	It was not formed
	Transparency/opacity	Solitude/crowd
	Industriality/traditionality	Frangibility/strength
	Industriality/traditionality	Flexibility/rigidity

Smoothness (9.06), transparency (9.35), and industriality (7.80) indicated the limpidity of glass, and the fatigue was based on stress-induced (5.22), solitude (8.94), frangibility (8.48), and rigidity (6.07).

Considering these significant factors, a concept that involves all features and represents their relation is obtained using experts’ opinions. Figure 2 depicts the pairwise mean comparisons of materials.

Figure 2.

The pairwise mean comparisons of materials based on experts’ opinions.

In particular, Figure 2 shows the characteristic of each material, in which the materials having the score range of 0 to 5 and 5 to 10 define the sensory features of the materials. Additionally, a score closer to 0 or 10 indicates the intensity of its effectiveness.

Discussion

Study Overview and Results

Two techniques were used in the evaluation process to identify the perceptual-emotional effect of using materials in the living space. Function, form, and sensory features as the main fields of space, elements, and materials were specified in the first step. Regarding the second step, the sensory features of materials were assessed in a pairwise manner. Then, the identification of significant factors is obtained from the analysis of the pairwise comparison matrices. Finally, expressions were provided to elucidate intended factors based on the experts’ opinions. The results of the present study are summarized in Table 11.

Table 11.

Mean of the Set of Pairwise Comparisons of Material Characteristics Based on Experts’ Opinions.

	Glass	Stone	Concrete	Brick	Metal	Wood
Stagnation/dynamism	3.80	8.48	8.67	7.96	6.83	6.17
Coldness/warmth	7.81	7.35	8.22	2.59	9.22	1.98
Artificiality/naturalness	7.72	3.50	7.63	4.76	9.30	1.58
Modernity/nostalgia	7.94	5.28	8.72	3.56	9.30	4.59
Industriality/traditionality	7.80	4.85	8.83	3.06	9.41	3.52
Beauty/ugliness	2.37	3.74	3.46	2.96	4.07	2.22
Frangibility/strength	8.48	2.67	1.56	2.76	2.43	3.72
Transparency/opacity	9.35	2.70	1.48	1.48	2.70	2.70
Stress-induced/tranquilizer	5.22	5.33	5.09	2.81	7.41	2.07
Rigidity/flexibility	6.07	9.28	8.48	5.85	7.02	4.85
Smoothness/roughness	9.06	4.81	3.52	3.04	7.04	4.46
Lightness/weightiness	8.15	2.28	2.17	3.70	4.26	7.65
Simplicity/complexity	8.94	6.48	8.26	7.19	6.96	7.22
Solitude/crowd	8.94	5.48	7.98	5.81	6.67	6.50

Based on the results, each of the six materials induced different emotions in users in the living space. The most important emotions for each material are as follows: Glass possessed the most sense of dynamism, frangibility, transparency, smoothness, lightness, simplicity, and solitude as well as the maximum sense of rigidity, weightiness, complexity, and crowd were observed in stone. Concrete had the most sense of stagnation, strength, opacity, and weightiness. While nostalgia, traditionality, opacity, and roughness were identified for brick, and metal possessed coldness, artificiality, modernity, industriality, and stress-induced. Finally, the wood had the most sense of warmth, naturalness, beauty, tranquilizer, and flexibility.

The buildup of sensory loading used in the space could be considered to represent the sensory characteristics of materials to achieve desired functions in living spaces. To this end, the materials can be combined by considering the indices and components, and constituent factors.

Based on the profiles derived from the subjects’ evaluation of materials, brick is regarded as a material having resistance, capability, motivative, and acceptability. Brick is a warm, durable, and natural eco-friendly material in industrial structures that evokes a sense of nostalgia. Further, it strengthens the user’s motivation for activity and place of interest by its own beauty, dynamism, and opacity. Furthermore, experiencing its tranquility evokes a great change of mood in the space, and the brick has weightiness, roughness, strength, and rigidity which provides an attractive space for interaction and relaxation. Applying concrete material to the living space demonstrates persistence due to its rigidity, roughness, and strength that is aesthetically pleasing to the user’s experience. Weightiness and explicitness can be observed to make the cold and industrial space in a modern style.

In the case of wood, its creative capacity indicates the amount of resilience as a soft, light, beautiful, traditional, nostalgic, and strong material. The use of metal in the living space represents the minimal and interweaved application of modern, industrial, soft, and cold materials. Stone as a cold, stagnant, and rigid material possesses strength, and its use results in developing a specific dignity and durability in the space.

Finally, applying glass to the living space can reveal the limpidity of the space due to its coldness, smoothness, industriality, intrinsic transparency, and frangibility. The opposite and contradictory features of materials have served to direct the present study toward the important purpose of the use of different materials in interior spaces.

Limitations and Future Studies

While arguing the advantages of the current research, we need to also note some weaknesses and avenues for future research. Even though the selected settings contained many distinctive elements that are familiar to respondents, it might be the case that respondents had never been there. Therefore, one may argue that the cultural context in which the materials are used can induce different emotions. Since we are distant from the foreign participants, it is therefore difficult to run studies that require more sophisticated procedural setups or responses from the participants. However, we understand that this limitation is inherent to any perception study on housing properties that relies on visual stimuli. We are encouraged to reflect on the cultural limitation of the participants and to consider the extent to which the findings would generalize to other groups.

Future studies could include a wider set of social contexts far beyond them. Furthermore, the exploration of social values might also offer a relevant contribution to a new body of knowledge in interior/housing design. We should consider that interior design is related to cultural contexts and, namely, to the materials presented. For instance, living space decoration, and aesthetics have played main roles in influencing housing preferences. Moreover, future follow-up studies could put focus on cultural factors that might have an influence on the perception.

Conclusion

The current study focused on the role of interior materials and found that architects need to articulate new principles of review considering the intrinsic features and users’ needs. In addition, the designer’s intention to use a specific material in the interior space represents the intrinsic feature of the space. Since the meanings are defined in relation to each other, the relationship between the features is multivalent and may shift over time and across different contexts for different social purposes. The cultural factors should be considered throughout the user-needs analysis stage. Bringing a truly cross-cultural focus creates an opportunity for environmental design scholars to develop a body of knowledge that is more representative of all humanity. However, future follow-up studies should explore whether cultural networks associated with specific emotions are as well affected by social context. In sum, interior design theories should be more efficient for practical use when applied to a specific population, as well as when applied to groups in distinct cultural contexts.

Footnotes

Declaration of Conflicting Interests

The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The author(s) received no financial support for the research, authorship, and/or publication of this article.

ORCID iD

Seyed-Abbas Yazdanfar

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