A Preferred Road to Mental Restoration in the Chinese Classical Garden

: The impact that classical gardens have on the well-being and quality of life of visitors, especially city dwellers, is an important topic. Scholars have previously focused on landscape aspects, such as water bodies, plants, rocks, chairs, pavilions, and public squares, in various green spaces but have overlooked the road settings that visitors walk on. This study used the Du Fu Thatched Cottage Museum as the subject region and employed a convenience sampling method ( n = 730) to analyze the preference and mental restoration of different road settings of Chinese classical gardens. According to the ﬁndings, the majority of visitors felt that the road settings in these classical gardens provided psychological recovery, and half of the roads received a preference score of ﬁve or above. The regression results indicated that nature, culture, space, refuge, and serene were found to be important predictive dimensions for both mental restoration and preference. Furthermore, this study divides landscape elements in road settings into two major categories (natural and artiﬁcial elements) and eight subcategories (trees, shrubs, lawns, roads, fences, walls, decorations, and buildings) to investigate the relationship between various types of speciﬁc road setting elements and visitors’ perceived preferences as well as restorability. The correlation results showed that in terms of preference, tree > lawn > path > fence > shrub > wall; in terms of restoration, tree > lawn > shrub > fence > path > decoration > building > wall. Overall, the ﬁndings of this research can improve visitor preferences and restoration in a given environmental setting, resulting in a more enjoyable experience.


Introduction
In 2018, 55% of the world's population resided in cities, a figure that is anticipated to increase to 68% by 2050, with an additional 2.5 billion people living in cities and with nearly 90% of the growth occurring in Asia and Africa, particularly China, India, and Nigeria [1]. The development of dense [2] and compact cities [3] has accelerated due to this evolving urbanization process, resulting in significant constraints on the natural environment and green space in cities. Thus, city sustainability is currently a significant topic of debate in urban planning and the built environment. The loss and degradation of green spaces as a result of dense cities as well as the development of transportation and population migration caused by the urbanization process deprive organisms of their habitats, reduce biodiversity, and damage the processes that result in urban ecosystems, among other negative effects [4]. In addition, city densification has had several negative consequences for humans, including increased congestion and reduced quality of life as well as negative psychological and physical health repercussions. Due to the significant health benefits of urban green spaces [5], researchers have discovered that there is an urgent need to identify new opportunities for natural interactions in current urban green spaces that may improve recovery [6].
To better understand the mechanisms of green space restoration for human health, public health researchers have developed several socio-ecological models [7,8]. Psychologically, urban green spaces can aid in reducing stress [9,10], depression [11], and anxiety [12] and improving mental health, happiness, and well-being [13]. It can also aid in increasing prosocial behavior and social connectedness [14,15], reducing aggression [16], and so forth. Physiologically, it can aid in reducing obesity [17] and diabetes [18], lowering blood pressure [19], and improving immune function [20] and general health [21], among other benefits. Furthermore, the amount of green space in communities has been linked to residents' overall health [22] and well-being index [13]. Green space has long been viewed as an important strategy for improving public health and quality of life.
To assess the degree of the perceived restoration of the environment, various self-report scales have been developed from different perspectives and needs, including the Perceived Restorativeness Scale [23], the Restorative Components Scale [24], the Short-Term Revised Restoration Scale [25], and the Perceived Restorative Characteristics Questionnaire [26]; in addition, Deng et al. (2020) [27] developed a Short-version Revised Restoration and Preference Scale for self-assessment by combining landscape elements and components, which is widely used in restorative potential and aesthetic preference.
In addition to the restorative nature of green spaces, Grahn and Stigsdotter (2010) [28] found that health-related studies of the psychological restoration of urban green spaces tend to highlight the perceived sensory dimensions (PSDs) of the landscape. They identified and described eight PSDs in green spaces as a methodological framework for the expert assessment of landscape quality and public health characteristics. The eight PSDs are serene, nature, richness in species, space, prospect, refuge, social, and culture. Several studies have shown that PSDs are reliable instruments for assessing urban green spaces [29]. Chinese academics have validated the potential of the eight perceptual dimensions in urban green space assessment and planning in China, arguing that studying these dimensions can assist Chinese policymakers in developing green space planning and management that meet public needs, thereby improving people's well-being [30]. Furthermore, some academics have stressed the importance of perceptive attributes in constructing landscapes with specific aesthetic qualities [31]. Grahn and Stigsdotter (2010) [28] found that people prefer the serene dimension, followed by space and nature, and that the dimensions of refuge and nature are most closely related to stress. Stoltz et al. (2016) [32] showed that the PSDs of green space play a role in stress reduction. Malekinezhad et al. (2020) [33] discovered that the perceived landscape characteristics of PSDs enhance the restoration experience in alignment with perceived restorative characteristics. The restoration potential and perceived dimensions of various green spaces have been discussed in recent studies, such as in forests and natural areas [34,35], parks [36,37], gardens [38,39], zoos [26], university campuses [33], and even cemeteries [40]. However, the serene and space dimensions were found to be the most common by Qiu and Nielsen (2015) [29], while the culture and social dimensions were the least common. In contrast, Chen et al. (2019) [30] discovered that social was the most common dimension in China, while culture and richness in species were the least common, which contradicts Qiu's study [29] in Europe. Thus, the effects of PSDs in various green areas are equivocal, and further research is needed to fully understand these mechanisms.
Additionally, landscape preference is a hotly debated and researched topic in the fields of environmental psychology and landscape architecture. Kaplan and Kaplan (1989) [41] used "Evolutionary theories" to explain visual landscape preferences and claimed that it was a beneficial human reaction that aids survival and well-being. They discovered that people's preferences for specific environments were linked to restoration because environmental preferences were based on environmental features that the perceiver may find functionally important. Many experts have since conducted studies on landscape preference and restoration, finding a favorable association between the two [39,[42][43][44][45].
Furthermore, many studies have discovered that the different landscape elements of green spaces can have varying degrees of influence on aesthetic preference and restoration. For example, natural landscape elements such as water, trees, flowers, and lawns can positively influence aesthetic preferences and psychological recovery [44,[46][47][48], whereas artificial landscape elements such as buildings and roads tend to degrade aesthetic preferences and psychological recovery [49]. However, studies have indicated that artificial features (decoration cover, statues) related to culture (poetry walls, cultural architecture) and art have a high landscape preference and restoration value [50,51]. These studies showed the importance of landscape elements for green space preferences and restoration, but in cases where artificial elements can adequately display cultural meanings, the relationship between natural and artificial landscape elements and preference and restoration has not been fully investigated.
Moreover, although it is an important part of green spaces and urban cultural heritage, classical gardens have received scant attention in environmental perception and restoration. Studies on classical gardens have mostly focused on historical features [52], design aims and art [53], and aesthetic value [54,55]. According to Pajin (1997) [56], classical gardens are places where people can retreat from the busy world and seek solace, relaxation, and wisdom through quiet walks and meditation. However, research on the relationship between their environmental elements and restorative qualities is still lacking. Thus, rather than being limited to the original design objectives of the garden makers, the focus of this study is on the experience of each genuine site in these classical gardens [57]. Walking spaces (roads or trails) are vital in classical gardens because they connect different sites of interest in the green space and are important places for leisure activities, such as walking, dog walking, and so on. Walking in urban green spaces has been shown to lower the heart rate [58], increase positive emotions and reduce anger [59], increase meditation and reduce stress [60], and even provide increased safety and fewer barriers [61]. Thus, road settings are important for the study of restorative urban green areas, such as classical gardens. Consequently, this study investigates the following:

•
Which elements of the road setting can influence the preferences and mental restoration of respondents? • How do PSDs behave in classical garden road settings? • Which PSDs are associated with mental restoration and preference for road settings?

Study Site and Locations
The most emblematic of Chengdu's ancient Chinese private gardens is the Du Fu Thatched Cottage Museum, which is in the heart of the city (Figure 1). The eight-hundredacre park, named for the Tang Dynasty poet Du Fu, is divided into two parts: the Du Fu Thatched Cottage (a major historical and cultural site protected at the national level) and Huanhuaxi Park (an open urban forest park and the only five-star open park in Chengdu, China).
In this study, ten diverse road settings in the Du Fu Thatched Cottage Museum were used as study stimuli ( Figure 2). The selection principles are as follows: (1) each road has different environmental features and design elements; (2) these roads can cover most of the tour area; and (3) there must be different road types, such as main roads, side roads, and recreational trails; (4) different levels of enclosure; and (5) no grand views in the view. The first road setting (P1) is a winding road going to the central region, with low shrubs contained by a bamboo fence, a few peach and towering trees, clusters of bamboo bushes as spatial dividers, and two thatched buildings to recreate Du Fu's life scene. P2 is a curving gravel walk with large lawns, shrubs, and unevenly spaced trees, a less noticeable sculpture in the middle, and a distant river. P3 has an eye-catching red wall, which is roughly two meters high and flanked by tall trees and bamboo plants, and a building typical of a classical garden stands to the right of the wall. P4 is a straight road with a large lawn, irregularly spaced trees on both sides of the road, and garden stones on the lawn. A promenade (building) with classical Chinese garden features and a large, wooded area can be seen in the distance. P5 is a winding gravel road with some classical garden buildings that display Chinese poetry culture on the left side of the road and a large lawn with dense and scattered trees on the right. P6 is a stone road flanked by large lawns dotted with irregular large trees as well as small trees such as chickpeas; ferns also flourish here. P7 is the main road of the park, with poems by Du Fu displayed on the white wall on the left for people to enjoy, a bonsai placed nearby, and a large lawn on the left, with stones dotted on top of the lawn and irregularly dotted trees. P8 is a winding road through sparse lawns, dominated by tall trees and open lawns, creating a tranquil, open scene. A sparse lawn area mainly includes tall trees and open lawns, creating an artistic conception of the dimensions of serene and prospect. P9 is a straight road that leads people to the attraction (bonsai garden). On both sides of the road are gray walls with bamboo bushes and some tall trees on the outside of the walls, and in the distance is the garden gate, which has a rich variety of bonsai. P10 is a main road, which is wide and flanked by lawns and irregular tall trees, mainly heather, camphor, and so forth. The trees completely cover the road in its shadow, granting visitors the feeling of being in the forest. In this study, ten diverse road settings in the Du Fu Thatched Cottage Museum were used as study stimuli ( Figure 2). The selection principles are as follows: (1) each road has different environmental features and design elements; (2) these roads can cover most of the tour area; and (3) there must be different road types, such as main roads, side roads, and recreational trails; (4) different levels of enclosure; and (5) no grand views in the view. The first road setting (P1) is a winding road going to the central region, with low shrubs contained by a bamboo fence, a few peach and towering trees, clusters of bamboo bushes as spatial dividers, and two thatched buildings to recreate Du Fu's life scene. P2 is a curving gravel walk with large lawns, shrubs, and unevenly spaced trees, a less noticeable sculpture in the middle, and a distant river. P3 has an eye-catching red wall, which is roughly two meters high and flanked by tall trees and bamboo plants, and a building typical of a classical garden stands to the right of the wall. P4 is a straight road with a large irregular tall trees, mainly heather, camphor, and so forth. The trees completely cover the road in its shadow, granting visitors the feeling of being in the forest.

Data Collection
The data for this study were gathered through convenience sampling from visitors to Du Fu Cao Tang. The surveys were gathered on weekends from 23 November to 13 December 2020. Twenty research assistants were pre-trained to comprehend the study's goal and the specifics of the questionnaires (Table 1). Thus, two study assistants were assigned to each road to deliver questionnaires to visitors in a random order. The study assistants were expected to stand by while the visitors completed the surveys so that they could answer any questions. The entire survey took roughly 10 to 15 min per visitor. The first part of the questionnaire consisted of four sections, the first being an assessment of landscape elements (multiple choice), including the presence of positive and negative landscape elements that they perceived to be present in the current road settings. The second section is the core part of the questionnaire, with the eight sensory dimensions of green space, each of which is explained with informative text to facilitate the

Data Collection
The data for this study were gathered through convenience sampling from visitors to Du Fu Cao Tang. The surveys were gathered on weekends from 23 November to 13 December 2020. Twenty research assistants were pre-trained to comprehend the study's goal and the specifics of the questionnaires (Table 1). Thus, two study assistants were assigned to each road to deliver questionnaires to visitors in a random order. The study assistants were expected to stand by while the visitors completed the surveys so that they could answer any questions. The entire survey took roughly 10 to 15 min per visitor. The first part of the questionnaire consisted of four sections, the first being an assessment of landscape elements (multiple choice), including the presence of positive and negative landscape elements that they perceived to be present in the current road settings. The second section is the core part of the questionnaire, with the eight sensory dimensions of green space, each of which is explained with informative text to facilitate the understanding of the eight dimensions. A five-point Likert scale (1 = "not at all", 2 = "a little", terms of "restorative experiences", "positive emotions", and "stress reduction" [62]. A five-point Likert scale (1 = "completely disagree", and 5 = "completely agree") was used to assess each item; the mean value of the three components was used as the final restorative score for each road setting. The fourth part is the landscape preference evaluation, where we asked respondents how attractive they found the landscape of the road from 1 (not attractive at all) to 7 (very attractive) and hope to revisit from 1 (do not want to visit again at all) to 7 (very much want to visit again). This was to ascertain respondents' preferences for the ten road settings. The average of the two components was used as the final preference score for each road setting. Information on the socio-demographic characteristics of the visitors was not collected and analyzed, as this was not the purpose of this study. Since each road had different visitor flows, it was difficult to ensure that the same number of questionnaires were collected at all locations. Therefore, during the final two weekends of questionnaire collection, experimental assistants who had already collected a larger number of questionnaires for other roads were reassigned to the remaining experimental locations to assist with questionnaire collection. Finally, the range of questionnaires collected for the 10 roads was 73-79; thus, 73 questionnaires were used as the sample size for the analysis of each road setting. This study was conducted with the approval of the Ethics Committee at Chiba University.

Data Analysis
The respondents' answers were statistically analyzed using the statistical software SPSS20.0, and the level of significance was set at p < 0.05. The relationships between different landscape elements, restorability, and preference were explored using Spearman correlations. Stepwise multiple linear regression was used to explore the drivers of restorability and aesthetic preference for all road settings.

Assessment of Road Landscape Elements
Participants were asked to assess two types of landscape elements, namely natural elements (trees, shrubs, lawns) and artificial elements (roads, wooden fences, walls, dec- orations, and buildings), which were used to understand whether these different garden elements were perceived as positive or negative (Table 2). Generally, most of the landscape elements in classical garden path settings were assessed as positive elements, but some visitors still perceived these landscape elements as negative. Specifically, trees were perceived as the most positive (456) landscape element, followed by garden roads (392) and lawns (371), while garden roads (101) and shrubs (92) were perceived as more negative elements of the landscape. These results indicate that trees are the most important landscape element in the path setting of gardens, while shrubs are less popular. Lawns are a positive element but are much less attractive than trees. Roads were both a positive element (392) and the most negative element (101), which illustrates the controversy in respondents' perceptions of different roads. Furthermore, walls, buildings, and fences were perceived as positive by some visitors, while decorations (i.e., infrastructure in the garden, bonsai, and landscape placement stones) were not as popular. A correlation analysis was performed to understand the relationship between the different landscape elements in classical garden paths as well as preference and restorability (Table 3). For natural elements, lawns, trees, and shrubs significantly influenced restoration. Among the artificial elements, roads and decorations were also able to significantly influence restoration but with a lower impact coefficient compared to the natural elements. In terms of respondents' preference evaluations, all artificial and natural landscape elements demonstrated significant impact. The coefficient magnitudes were as follows: trees > lawn > roads > fence > shrubs > walls > decorations > buildings.
Two stepwise multiple linear regression analyses were conducted to explore the effects of PSDs on mental restoration and preference. The dependent variables for both regression models were preference and mental restoration. The results of the correlation analysis (Table 5) indicate that recovery increased with preference. The culture dimension was not significantly correlated with the restorative, prospect, space, and serene dimensions, while the remaining seven PSDs had significant positive correlations with both preference and restoration.
Furthermore, a stepwise multiple linear regression analysis was employed to establish a quantitative association among PSDs, restoration, and preference for road settings. The association among the eight PSDs, preference (F = 77.03; p < 0.001), and restorability (F = 123.83; p < 0.001) are shown in the results ( Table 6). The presence of model tolerances (tolerance < 0.2) or variance inflation factors (VIF > 10) indicate a potential multicollinearity problem [63], whereas there is no cointegration problem in the current model (the lowest tolerance = 0.365; the highest VIF = 2.741); thus, the results are considered acceptable. According to the model's findings, the dimensions of nature, culture, space, shelter, and serene have a substantial impact on preference evaluation, whereas the dimensions of nature, culture, prospect, space, refuge, and serene have a large impact on the restorability Two stepwise multiple linear regression analyses were conducted to explore the effects of PSDs on mental restoration and preference. The dependent variables for both regression models were preference and mental restoration. The results of the correlation analysis (Table 5) indicate that recovery increased with preference. The culture dimension was not significantly correlated with the restorative, prospect, space, and serene dimensions, while the remaining seven PSDs had significant positive correlations with both preference and restoration. Furthermore, a stepwise multiple linear regression analysis was employed to establish a quantitative association among PSDs, restoration, and preference for road settings. The association among the eight PSDs, preference (F = 77.03; p < 0.001), and restorability (F = 123.83; p < 0.001) are shown in the results ( Table 6). The presence of model tolerances (tolerance < 0.2) or variance inflation factors (VIF > 10) indicate a potential multicollinearity problem [63], whereas there is no cointegration problem in the current model (the lowest tolerance = 0.365; the highest VIF = 2.741); thus, the results are considered acceptable. According to the model's findings, the dimensions of nature, culture, space, shelter, and serene have a substantial impact on preference evaluation, whereas the dimensions of nature, culture, prospect, space, refuge, and serene have a large impact on the restorability of road settings. Thus, the model's five sensory dimensions of nature, culture, space, refuge, and serene are consistently significant predictors.

The Preferred Landscape Elements of Road Settings
According to the results (Table 2), the majority of landscape elements were evaluated as good and positively connected with preference and restoration. Landscape elements were divided into two types in this study: natural and artificial landscape elements. Natural landscape components were divided into three groups: trees in the upper space, shrubs in the middle space, and grass in the lower space. Plants are the most important landscape element in green spaces; numerous previous studies have reported on people's preferences for different types and characteristics of plants in the landscape as well as the effects of different types of plants on people's aesthetic preferences and restoration potential [64]. In terms of trees, classical gardens typically have older trees than are found in newly constructed modern parks. In addition, Du Fu Thatched Cottage Museum is renowned as Chengdu's urban forest due to its diverse tree species and enormous area of vegetation. In this context, our findings reveal that people generally regard trees and the woodlands they create as beneficial components, with a strong link between restoration and preference. This result is consistent with previous research: Nordh et al. (2011) [65] discovered that increasing the number of trees improves aesthetic preferences and restoration potential, while Kaplan (1995) [66] found that increasing the number of trees enriches the landscape environment, attracting more animals and creating a new ecological space. Furthermore, when compared to other natural features, respondents tended to place the least value on shrubs, which is consistent with the findings of Nordh et al. (2011) [65]. According to Ignatieva et al. (2020) [67], lawns in urban parks are typically considered one of the most essential components of the environment and one of the most commonly used types of urban green infrastructure and recreational locations. One of the primary values of lawns is that they provide space for social activities, such as picnics, resting, sunbathing, dog walking, games, and sports [68]. Although lawns are one of the landscape elements that can significantly influence preference and restoration in the results, lawns were not the most popular natural element in this study. One reason for this is that most of the lawns in Du Fu Thatched Cottage Museum are forbidden for visitors, prohibiting such interactive experiences. Second, the towering and lush trees appear to effectively pull people's attention away from the lawns, making them less appealing.
Artificial landscape elements are often viewed negatively [69]. However, some studies have found that certain culture-related elements [51,63,70,71], such as local traditional houses, historic buildings, historic landscapes, corridors, poetry walls, pavilions, and landscape statues, are considered positive man-made elements because of their traditional architecture and unique cultural qualities and thus have a significant impact on restorative attributes. The architecture of the Du Fu Thatched Cottage Museum was largely rebuilt and built throughout the Ming and Qing periods and are historically and culturally significant. Despite the fact that the walls are primarily new constructions, unlike general walls, they not only have an enclosing function. Simultaneously, the poems of Du Fu on the walls also contribute to the cultural quality of the surroundings. Most respondents stated that culturerelated items with historical and cultural significance (such as architecture, landscape decoration, walls, roads, and bamboo fences) have a favorable impact on their preferences. Furthermore, although walkways are commonly thought of as negative artificial aspects in modern parks [70], this study discovered that road elements have a considerable positive effect on both preference and restorability. While in classical gardens, the "winding road to somewhere serene" is a typical form of expression, according to Lai et al. (2020) [72], people like small, unguided roads with specific curves because such paths serve to provide a peaceful environment for them to engage in psychological repair, hence appealing to their desire to explore. Moreover, classical gardens include distinct road elements (paving materials, textures, and fences) that are dissimilar to city streets, which may contribute to a sense of being away from home and work as well as allowing people to forget about some of life's pressures and problems, thereby boosting recovery.
In brief, natural landscape elements, on the one hand, are more restorative than manmade landscape elements. However, some man-made landscape components with cultural significance can have a significant and positive impact on people's restorative potential. On the other hand, some culturally significant artificial elements (roads and fences) outweigh natural elements in terms of preference (shrubs). As a result, the findings of this study imply that culturally relevant artificial components can be appreciated by visitors and contribute to the aesthetic appeal of the environment.

The Representation of PSDs in Classical Garden Road Settings
Currently, PSDs are being used in a variety of green spaces across various nations and regions, with the goal of (1) determining people's perceptions of different dimensions and (2) determining the relationship between users' perceptions of recovery and preferences [28][29][30]33]. In this study, we focus on people's experiences of classical garden road settings and examine them through the identification of the eight PSDs.
Our results (Table 4) indicate that serene is the most generally perceived dimension in classical garden road settings, which is consistent with the results of Grahn and Stigsdotter (2010) [28], who found that serene is one of the commonly perceived dimensions. The second dimension is nature. Gray spaces such as buildings and streets are busy areas, limiting the amount of space available for people's activities to be managed and allocated to specified areas; however, in the road settings of green spaces, people's inherent cognition of green spaces is that they may more freely undertake all types of green activities, such as running, strolling, sitting, lying down, and so on. This natural experience boosts pleasant emotions and meets people's non-material and non-consumption requirements [73]. The third dimension is that of refuge, which shows that classical gardens' enclosed and safe environmental attributes have been manifested [28,30]. Grahn and Stigsdotter (2010) [28] support the idea that the dimensions of refuge, nature, and calm are the most desired dimensions for highly stressed people. Fourth, culture is a perceptible component that is inconsistent with other forms of green space results [28,30,74] and can be linked to the presence of cultural heritage in the classical garden. Moreover, the dimensions of richness of species and space are less noticeable. The experiment was conducted in the winter, making it almost impossible to detect wildlife (birds, butterflies, squirrels, etc.) and difficult to find colorful plants, resulting in a lower perceived species richness. Chen argues that in China, green space users only experience species richness in urban forests, which are often located far from cities, rather than in natural and semi-natural green spaces in overcrowded cities [75]. This is most likely due to the high population and scarcity of natural and semi-natural green spaces in the metropolitan environmental settings of China. According to Grahn and Stigsdotter (2010) [28], too many roads and paths would disrupt the spatial dimension because the roads themselves are meant to connect public spaces with various attractions; thus, the space dimension is an uncommon perceived dimension in road settings. Finally, prospect and social are among the most uncommon dimensions in road settings. This could be due to the lack of defined areas for social activities and the presence of enclosures (e.g., dense vegetation and walls) that limit the view.

PSD Predictors Driving Restoration and Preference
The results (Table 6) show that in a classical garden's road setting, nature, culture, space, refuge, and serene are significant factors affecting preference; for mental restoration, the dimensions of nature, culture, space, refuge, serene, and prospect are significant predictors. In total, nature, culture, space, refuge, and serene were found to be important predictive dimensions of mental restoration and preference.
First, the nature dimension was found to be a strong predictor of restoration and preference, as in prior research. Stigsdotter et al. (2020) [76] discovered that a city park with a strong presence of nature could be preferred. According to Kaplan (1990) [77], nature is the best environment for involuntary attention and resting-directed attention, which means that the dimension of nature has a significant impact on restoring directed attention for urban individuals. Moreover, Pálsdóttir et al. (2014) [78] suggested that nature's restorative effect is rich in many aspects not only because it can have a positive impact on recovery but also because experiences in nature can inspire people to discover new and natural things. Since they were established long ago and are protected, classical gardens, as a type of cultural heritage in the city, have more lush, historical trees or woods than the urban environment, making it easier for people to experience the natural dimension. As a result, the nature dimension in the road settings of classical gardens is an important characteristic that influences restorability and preference.
Cultural heritage has been demonstrated to be highly restorative [50]. In the Western context, the experience of manmade components shaped by humans, such as fountains, statues, and canals, is referred to as culture-related elements [76]. However, in the Chinese cultural context, culture is more likely to be portrayed through the artistic conception of honoring ancient people or historical figures in addition to figurative items, such as sculptures and cultural walls. Chinese classical gardens can promote place attachment and identification for respondents as a physical symbol of Chinese culture, leading to increased restorative and aesthetic preferences [43]. Culture, as an important factor in aesthetic pleasure, is more likely to be perceived in road settings and increase restorative experiences, which is in accordance with the current findings. As a result, improving visitors' perceptions of cultural dimensions to boost their restorative levels is a key proposition for future urban green spaces.
Grahn and Stigsdotter (2010) [28] found that the dimension of serene is the most popular among visitors. According to den Bosch et al. (2015) [79], serene can greatly reduce the risk of mental illness. People feel comfortable and calm in a tranquil atmosphere where they are not bothered by other people or traffic, that is, away from the city's noise and crowds [80]. The serene dimension, however, does not imply that there is perfect quiet [81]; some natural sounds, such as the wind, water, birdsong, and insects, can still be heard. As with culture, the restorative intensity of serene is dependent on the quality of the surroundings, which means keeping them well-maintained and clean, devoid of weeds, litter, and graffiti, which improves restoration [74]. Thus, in terms of serene, the preservation of environmental quality and the restriction of pedestrian movement are two key variables that influence the preference and restorative quality of road settings in classical gardens.
Space is an important predictive PSD of mental restoration and preference. Space is described as a wide-open area with a degree of connection. Qiu and Nielsen (2015) [29] discovered that space is easy to perceive in green spaces. People are free to move and play in green spaces that are spacious enough because they live in crowded urban environments (gray spaces) for lengthy periods of time. According to Kaplan and Kaplan (1989) [41], the desire for space and restoration stems from a natural human desire to migrate away from heavily populated regions in pursuit of a naturally coherent environment that allows people to feel as if they are stepping into another world. Around the road settings in classical gardens, there are many forests or enclosing walls, and these elements add to the sensation of the enclosure of the landscape, making visitors feel psychologically secluded from the outside world. As a result, the spatial dimension can provide a high level of restoration and preference.
Consistent with previous studies [28,74], the dimension of refuge has one of the strongest and most significant positive connections with stress. People can self-regulate by spending time alone, resting, and meditating in a sheltered environment to reflect on their current situation and understand their real emotions [82]. Meanwhile, refuge could influence people's preferences. This is because the ability to seek refuge is critical for human survival, and the adaptive function of a preference for specific landscape elements improves people's mood [83]. This implies that the road settings in classical gardens are environmental attributes associated with security and enclosure and that they may provide people with restorative and preferable experiences. Finally, prospect is another important predictive dimension of mental restoration. According to Appleton (1975) [84], when ancient humans searched for habitable environments, prospect was considered an essential quality. One of the most important aspects of visual control of the environment, which allows us to perceive danger, is that people intuitively choose an environment that is conducive to survival [85]. Even though plants and walls help to create a sense of enclosure in these settings, visitors standing on the roads can plainly see both ends of the walk, giving them a greater sense of control over their surroundings. Therefore, proper views in the road settings are essential, as they can help the visitor have a more restorative experience by boosting their understanding of environmental information.

Limitations
This study still has some limitations. Firstly, this paper only selected ten different types of roads in a classical garden for study, but there are some other road types in other Chinese classical gardens that are not covered in this paper. Therefore, more road settings could be selected in future studies. Secondly, this study did not collect demographic characteristics. Future research that includes participants of different ages, occupations, and cultural backgrounds could be more valuable. Lastly, the study was only conducted in November and December when it was almost winter. This season may cause some bias in the perception of species diversity (such as animal activity, plant coloration), and other seasons could be further consideration to increase reliability of the results.

Conclusions
Roads are the most important components for people to explore green spaces. However, studies on green spaces disregard these crucial components, namely visitors' perceived preferences and the restoration of road settings. In this research, a field questionnaire was used to collect a sample of 73 visitors for each road setting, and the PSDs, preferences, and mental restoration of 10 different classical garden road settings were analyzed. The results indicate that (1) for preference, some culture-related artificial elements will have a stronger influence than natural elements in the following order: tree > lawn > path > fence > shrub > wall > decoration > building; in terms of restoration, the artificial landscape elements of road settings can also significantly and positively influence mental restoration but are all weaker than the natural elements as follows: tree > lawn > shrub > fence > path > decoration; (2) in the road settings of classical gardens, serene is the most perceived dimension, followed by nature, refuge, culture, richness in species, and space. (3) Nature, culture, space, refuge, and serene were found to be important dimensions of mental restoration and preference. Furthermore, this study is the first to apply PSDs to analyze different road settings in classical Chinese gardens. Finally, it is demonstrated that PSDs can be effectively applied to specific settings and objects in urban green spaces based on visitors' perception level of eight sensory dimensions.