Recognising Tactual Aspects of the Urban Environment Through Walking—A Critical Discussion of Touch-, Tactile-, and Haptic-Based Sensewalk Methodologies

Abstract

Tactile aspects of the urban environment may be recognised through various capacities of human sensation, including cutaneous, kinaesthetic, and proprioceptive awareness. Haptic attributes often need intentional engagement for ultimate experience and information provision, but it is exactly this imprecision that initiates challenges when dealing with tactility in a space. Whilst tactile components can be experienced when stationary or through walking an identified space (a sensewalk), there is no standard method for tactile sensewalk implementation. We therefore critically discuss common methodologies, outlining benefits, disadvantages, and suitability for each identified sensewalk method. We find that immersive sensory enquiry approaches are well suited to reveal past experience of sensory perceptions, deeper understandings and rediscovery of places; the recording of dimensional measurements is appropriate when determining linkages and correlations between physical and perceptual dimensions; and interviews and post-data collection reflections provide an opportunity to explore sensory characteristics and experience, and for realisation of local heritages. Furthermore, unusual methods such as the visualisation of urban textures and multimodal post-processing techniques are identified and discussed.

1. Introduction

Tactile aspects of the urban environment may be recognised through various capacities of sensation related to the human body’s sense of touch. These capacities include sensations at the dermal level (cutaneous), including perceptions of pressure, vibration, and temperature, body motion (kinaesthetic), position of the body in space (proprioceptive), and sense of balance through the vestibular system [1,2]. Such complexity provides a wide range of information to an individual, but it is exactly this imprecision that initiates challenges when dealing with tactility as it can include all active or passive epidermal sensations, including those of temperature and pain or discomfort, yet it can also deliver information concerning touched external objects, including texture, compliance, slipperiness, consistency, and form [1,3]. Environmental perception through tactile experience can also extend to positional awareness, balance, the memory of past experience and can even incorporate other senses, including the aural [4]. The tactile sense is therefore distinctive in that it concerns the internal, external, and mental human dimensions, and, therefore, it could be understood as an embodied way of encountering and understanding the world.

Tactile experience has been shown to contribute to ‘intense embodiment’ and increased awareness of corporeality in outdoor physical activity [5] and is an important aspect of sensory garden design for children with special educational needs [6]. Variation in ground terrain textures as experienced through the feet can provide emotional experiences which motivate regular physical activity [7], and barefoot walking can allow for a deeper connection to nature [8]. Furthermore, engagement of cultural heritage through explorative touch by the hands can create an interactive positive educational experience [9,10].

The power of tactual aspects is perhaps best epitomised in the growing examples of touch tables and didactic development in the museum context, which can lead to more intimate, emotional experiences [10,11]. A particular example can be seen at the university museum in Trondheim (Norway). Here, journeys from ‘first generation museums’ (essentially untouchable exhibitions in glass cases) through ‘second generation museums’ (hands-on and minds-on approach) and, finally, to ‘third-generation museums’ (visitors wearing Middle Age costumes and taking a walking pilgrimage to relevant historic sites) allow visitors to encounter the various tactile dimensions of the fourteenth century’s The Bocksten Man [12]. Visitors engage with cutaneous sensation (touching objects, wearing robes), kinaesthetic sensation (walking along textured paths), and proprioception (understanding cathedral space), whilst participating in a replicated embodied experience of the mediaeval man exemplified in the collection. Such a multifaceted tactile undertaking can allow for more enlightened communication and stimulate the imagination.

In a similar vein, we can perceive modern cityscape aesthetics through our various tactile capabilities. For visible tactile elements, we can observe building textures, virtually perceive building profiles, and ‘embrace’ roofscapes; for the invisible, we can feel the volume and height of city buildings, flux of microclimates, and sense the “inner movements, pulse and rhythms” of urban centres [3]. These tactile components can be experienced whilst stationary or through walking an identified space, with the method of identifying sensory experience while walking being known as a sensewalk. The act of walking allows the walker to be more focused on the senses, and, through this literally grounded approach, we become “fundamentally and continually ‘in touch’ with our surroundings” [13]. While early records of sensewalks used in social science research focused on the aural elements of cities [14], sensewalks have since advanced to investigate all standard five-sense experiences, either individually or at the multisensory level.

Considering the wealth of research pertaining to soundwalks (aural perception) [15,16] and smellwalks (olfactory perception) [17], there has been little discussion of tactile/haptic-based walks and methods thereof. This paper explores tactile-based sensewalks, with a primary focus being to present the diverse range of methods employed. It will first outline the disparate methodologies employed, followed by a discussion of the benefits, disadvantages, and suitability of each method, with respect to the research focus.

2. Tactile Research Methods and Theory

A systematic search was undertaken using the three databases Scopus, Google Scholar, and ProQuest (Figure 1). Tactile terms were searched in conjunction with ‘sensewalk’ using Boolean operators, e.g., “sensewalk AND (haptic OR touch OR tactile)”, using wildcards where pertinent, utilising groups ‘all fields’, ‘all types’, or ‘anywhere’. Databases were searched for any records published until the initial search date (7 January 2023), with the search updated on 22 September 2023. Following peer review, we extended the search to include additional search terms, of “sensory walk” AND (haptic OR touch OR tactile), “haptic walk”, and “tactile walk”, using the above strategy.

The search yielded a total of 451 items, and following the removal of duplicates (n = 47), 404 usable items were screened under pre-stipulated exclusion criteria. Based on text in title and abstract viewing, records were excluded if they did not employ a sensewalk to specifically investigate tactile-related sensory components or did not discuss sensewalk methodologies. These criteria resulted in the rejection of 324 records. Records were also removed if they were written in a language other than English (n = 20).

Full-text screening resulted in the exclusion of 42 records due to inclusion criteria not being met, or descriptions/discussions of touch-based sensewalk methodologies being unclear, while 4 other records were excluded due to production of analogous research across multiple formats (thesis, article etc.). A total of 14 references were then considered for inclusion in this literature review.

Using these references, we found that there was a wide diversity of approaches and methodologies in tactile research to date (Table 1). Haptic-related sensewalks ranged from research collecting specific sense data (textures as visual, thermal data) to the theoretical notions of utilising sensewalking as a sensory enquiry tool to realise and experience embodiment of place.

2.1. Embodiment and Exploration of Place

Through discussion of methodologies as employed in the WalkingLab project, Springgay and Truman [18] consider the use of haptic walks beneficial to stimulate ‘sensory enquiry’. By engaging young children to explore tactile experiences such as with discarded Eucalypt bark or by climbing and touching public sculptures on a series of walks, themes of human and nonhuman interactions and themes of migration and movement of place are realised. The authors suggest that, as the process of walking emphasises vibrational flow through active movement in a specific place, sensory enquiry can “materialize a more haptic relationship to place” [18], and engagement in haptic-based walking can, therefore, enable a deeper sensory understanding and appreciation of embodiment and place.

In continuing the theme of embodiment, Anemogiannis and Theocharis [19] used multisensory walking as a way of uncovering, embodying, and emplacing stories of the island of Kythera, Greece. Considering that specific places of meaning are located along paths delineated by movement, they suggest that re-walking these paths can “revive the narratives associated with them and the meanings ascribed” [19]. Three silent sensory walks of a 30–40 min duration were undertaken by groups of local participants (n = 6 to 13), with the aim of achieving an immersive connection with the place and associated stories. The route and stops were pre-designed by the participants themselves, being based on familiar landmarks and interest points associated with local stories. Active engagement with the surrounding environment was encouraged of the participants during the walk to effect memory through sensory experience, and such touch-related actions included “shaking reeds to make sound, touching natural materials, throwing stones to test the echo, balancing on curved surfaces” [19]. Sensory impressions and mental associations were documented by sound recorders, cameras, and notebooks, and participants shared their ideas and recorded material with each other in post-walk group discussions. Key methodological findings emerged from these sessions such as positive feedback on walking in an exploratory and experimental manner, as well as the notion that an awareness of memory associations in a familiar environment is effected through concentrating on the senses and that sensory walks enable a fresh rediscovery of familiar places [19].

2.2. Sensewalks to Explore Tactile Elements Within a Multisensory Experience

To explore how smell, sound, and touch can form a ‘sensescape’ of a place, Gomes undertook fifty in situ ‘sensetalks’ across multiple environments of Bishopsgate (London, UK)—with a sensetalk being a street interview which enables immediate participant feedback of their sensory experience whilst they are actually experiencing it [20]. Selecting participants on-site allowed a more direct connection between sensory perception and the study location, and semi-structured and open-ended interviews were conducted at different stopping locations along a pre-determined sensewalk route (20 min duration, length 1.7 km). Participants included both locals (residents and workers) and visitors, with the understanding that locals bring insights of familiarity, and visitors bring insights of strangeness and are therefore generally more curious towards the environment. Questions pertaining to the each of the senses were asked at each stopping point, with specific touch-related questions including “how do you feel this space?” [20]. Key methodological features of this article include the resultant identification and development of a series of semantic categories for participant perception of non-visual sensory stimuli and associated description criteria.

Another study investigating the multisensory experience of the Spice Bazaar of Eminönü (Turkiye) collected verbal expressions of first-time visitors during a researcher-guided sensory experience walk [21]. Comments were recorded through a ‘think aloud protocol’, consisting of participants verbalising their thoughts in conjunction with an observer visually documenting participants’ reaction. All sensory experiences were divided into either tangible or intangible parameters, and tactile parameters were divided into those considered tangible such as touching specific objects (e.g., ceramics, soaps, jewellery) and general crowding, and those considered intangible elements such as the feeling of intense airflow or warmth, alongside more subjective feelings including a sense of ‘anxiety’, being ‘uneasy’, or having ‘energy’ [21].

A university cultural programme which aimed to identify, document, and describe multisensory experience through a sensory walk employed the use of literary recording in result presentation. Believing that verbal or photographic documentation would largely limit experience to visual/auditory aspects, student experiences of a one-hour sensory walk along a pre-determined route were expressed in written form in order to focus on non-visual sensory modes [22]. Expressions often took the form of poems or prose, and, although this technique allowed for personal reflection of multisensory aspects and associated linguistics, it was noted that students sometimes “struggled to find the right language to describe their sensory experiences” [22].

In contrast, one study took an entirely visual-centric approach in presenting multisensorial data. Using a tripartite mapping methodology, multiple participant pairs wandered the Franklin Delano Roosevelt Memorial (Washington, DC, USA) to (1) explore the environment by focusing on the senses through guided blindfolded walks, (2) briefly create a graphical transcription of the previous sensory walk (‘map-score’), and (3) create a subsequent map-score as a designed sensory walk for a different participant pair [23]. Whilst the initial map-scores highlighted experienced tactile components (for example, temperature sensations and changes, path stability and textures) alongside other sensory components (for example, smell and sound), the final map-scores of sensory walk design largely focused on tactile activities and exploration. Inspired by the actions of the previous walk, these map-scores read like a guide for immersive enquiry, with written instructions including “feel texture with your feet slowly”, “find branch—hang onto it”, and interestingly, demonstrating how multisensory engagement develops from tactile processes: “pick grass—smell it—throw it” and “find tree branch—rustle leaves—listen”. This sensewalk methodology therefore allows for a description of tactile experiences, from both the past and the future [23].

Two studies in the book Multisensory Landscapes—Theories and Methods used a phenomenological approach for multisensory walks [24]. The first recognised that a phenomenology methodology was well suited for exploring subjective experience and perception, in particular that of atmospheres. Research focused on the atmospheric effects of constructed thematic worlds of zooscapes in Stuttgart (Germany) and the influence of these on the observers, with phenomenological-based descriptions used to interpret zooscape experience and perceptions [25]. While this approach does not specifically focus on tactile parameters but rather on a wide range of experienceable perceptions through “a sharpening of the senses”, the tactile experience was naturally brought out through textural descriptions and reflections, including those of temperature, space and crowding levels, textured footways, humidity levels, and observational positioning [25] (p. 204). The second study used a similar approach to examine visitor perceptions of a flood-damaged town, with data collection employing the use of a voice recorder to enable real-time discussion between the researchers and individual descriptions [26]. Route choice was guided by impressions regarding the influence of sensory potential, and routes were traversed in more than one direction, which highlighted features missed from the initial transect direction. Again, while tactile components were not specifically targeted, such a phenomenological approach allowed “a broad access in immediate experience, … (taking) into focus everything that comes within reach”, and tactile components were recorded in descriptive text, including those of temperature, humidity, texture of footways, and path obstacles [26].

2.3. Sensewalk Post-Processing Techniques

An earlier paper highlighted issues of authenticity, perception, and consciousness as limiting factors of employing the sensewalking method, with authenticity issues including the notion that a sensewalk can only capture one aspect of the “multimodal perception of the experience”, and, thus, it can only portray a partial record rather than a total representation of the environment [27]. Whilst accepting the inherent limitations of reconstructing perceptual experience, the authors utilised different methodological recording processes of sensory walk data to echo the wide range of sensory experience as actually experienced during the original sensewalk. On a pre-determined route in London, taking advantage of multiple environmental locations, researchers traversed the same path approximately ten times, both in full and in part, and in both directions, focusing on different sensory components at a time—those of sight, sound, olfactory, and haptic. Whilst the various methods employed in this study to record sensory perception mainly focused on the visual or aural dimensions (different microphones, photos versus notetaking), it was the employment of data processing techniques that highlighted experienced haptic components from the sensewalk. For example, visual imagery was post-processed using the motion-factor Isadora software package to reveal the kinetic and texture components of an image, GPS visual output viewing angles were manipulated to create a “more haptic, visceral response to the re-presentation of the movement of a person through an environment”, and text recordings were rephrased poetically to emphasise more of the haptic, tactile, and kinaesthetic components of the experience than what had been originally scripted [27]. Of note is reworking or enhancing original data, allowing for the contemplation of emotional responses to offer a well-founded “sense of the walk, rather than simply a record of the act of the walk”, which recreated somewhat paradoxically a more authentic version of the sensory experience [27].

2.4. Visualising Urban Textures

In contrast to the above articles discussing haptic theory and authenticity of a sensewalk experience, other research investigated locationally specific tactile sensory components in a more comparative data-driven manner, such as identifying and recording certain elements of touch identified during multisensory sensewalks through a visual medium.

A doctoral research study investigating the urban environment of Istiklal Street (Istanbul, Turkey) used the sensewalking method to explore aspects of the five major sensory components. Grounded in a phenomenological approach and recognising the embodied nature of haptics, Kartal deemed it unnecessity for participants to physically touch surfaces of buildings or objects to sense a surface or texture. Believing that the eyes “expose the surface or object characteristics … (and) … sculpt a three-dimensional image for the observer”, specific haptic-based data collection methods reflected this and included documenting building textures through digital imagery [28]. Using local participants, three sensewalk groups traversed a pre-determined route in silence for around one hour, with haptic data collected through photos taken on mobile phones, recording the most typical texture/material/graphic characteristics as experienced on the walk. Whilst no stopping points were scheduled, participants were allowed to stop momentarily as required to undertake the task. In conjunction with demographic and visit-centric questions, thematic questions on sensory qualities were asked, with the haptic related question being “by using your mobile phone, could you please zoom on the Street floor and building surfaces to take photos (up to 10 pieces) of the most typical texture/material/graphic characteristics as you walk on Istiklal Street and rank them as (−) unpleasant or (0) neutral or (+) pleasant according to how does it make you sense?” [28]. Following the collection of data, discussions took place between the participants and the researcher concerning study sentiments.

Another doctoral study, looking at cultural mapping as a method to understand the sense of place of Porto (Portugal), utilised sensewalks for six visual artist participants along participant-designed routes. The choice of artists as participants was considered highly relevant for their inherent curiosity, creativity, and drawing and mapping skills [29]. Walks were used to hone in on various multisensory properties of urban space, with the choice of sensory component(s) and methods being ultimately left up to the artists [29]. One artist showed interest in investigating the textural components of the city, but, unlike the work of Kartal, where these elements were digitally recorded, the artist participant translated the city’s haptic experience into a visual form physically, with textures transferred onto a paper medium through the rubbing of a drawing charcoal, resulting in a book of urban patterns as perceived by the individual [29].

2.5. Thermal Dimension Sensewalks

Finally, temperature- and heat-related aspects of the haptic medium have been investigated in some studies, often in conjunction with the investigation of other sensory components of a location.

To explore correlations between dimensions (physical and perceptual) of luminous, thermal, and auditory facets of multiple locations of a university campus in Biskra (Algeria), researchers employed a combined visual, sound, and thermal walk. Here, three groups of students traversed a pre-determined route, with two methods in play: in the first, participants recorded physical dimensions of the environment during the sensewalk; and in the second, students completed an in situ questionnaire after each sensewalk [30]. Field methods included recording thermal environment dimensions of air temperature, relative humidity, and wind speed (through a Multifunction Meter), alongside measurements of mean radiant temperature and physiologically equivalent temperature (through sky-focused fish-eye images). Subjective measurements were obtained from a questionnaire based on fourteen different attributes measured on a seven-point scale, four of which concerned thermal environment evaluation: hot/cold, humid/dry, satisfied/dissatisfied, and pleasant/unpleasant [30]. The authors believed that a major strength of this study was the use of both objective and subjective approaches in methodology, although they recognised that the research was limited to examining physical dimension correlations and verifying perceptual associations and that a gap remained regarding “the determination of the link between the physical dimensions and the participants’ qualitative responses” [30].

Thermal walks were also employed by Vasilikou in field research investigating microclimatic thermal attributes in Rome and London. In this study, the thermal walk method comprised a “technique that analyses the urban climate, the morphology of spaces and the way people perceive their combined effect, through a series of structured walks with simultaneous environmental and human monitoring” [31]. Employing the use of a purpose-built portable weather station fixed on a lightweight trolley, specific sensors fixed at a height comparable to the average person measured air temperature, globe temperature, wind speed and direction, and illuminance. The device was transported along the thermal walk routes in conjunction with participants who recorded perceived thermal sensations [31]. Six points of measurement were devised for each thermal walk for comparative analysis, and supplementary photographs were taken at these points to visualise sun or shade variability. Subsequent thermal walk research in Paris employed a smaller tripod-based weather station which then included relative humidity measurements, and participant questions were developed to obtain an ‘actual sensation vote’ on the parameters of thermal sensation, wind, sun, perceived thermal comfort, and differential thermal sensation (on a seven-point Likert-type scale). Of interest to this article is the consequent development of a radar diagram method which allows the presentation of linked objective and subjective thermal data simultaneously, in quantifiable terms [31].

A more recent study by the same researcher investigated sensescapes of the heritage city of Canterbury (United Kingdom). Again using the sensewalk method, this study investigated the sensory perception of thermal cues alongside other components of ‘atmospheres’ (a sensory combination of visual, acoustic, olfactory, thermal, and haptic cues), using groups of 5–10 participants across three unique routes near historic centre landmarks [32]. Participants were requested to record the intensity and quality of each sensory cue as they traversed the route. Subsequent mental mapping workshops took place to further portray the perceived multisensory experience of the location, and multiple map creation techniques were utilised, including those of visual, textual, hybrid, and graphic notations. The author noted that the provision of such multiple approaches in mental mapping methodologies provided a “diversity of perceptual awareness” from the participants, and revealed the potential for “narrative and story building around the experience of space” as experienced through sensory perception.

Table 1. Different methodologies identified for on-site tactile sensewalks (a cross denotes a method explicitly not employed).

Article	Participants				Site	Route				Data Collection								Data Collection Interview				Research Aims (Methodology)
	Recruitment	Solo	Duo	Group		Pre-Determined	Open	Stopping Points	Duration	Photography	Rubbings	Questionnaire	Think Aloud	Narrative	Audio Recording	Physical Measurements	Mapping	Pre Walk	During Walk	Post Walk	Post Walk Discussion/Workshop
[21]	Voluntary first-time visitors			✓	Indoor bazaar	✓				✓		✓	✓				✓	✓				To analyse the sensory stimuli experienced by participants in multiple zones of a bazaar (participants’ verbal feedback)
[19]	High-school students and local community members			✓	Multiple outdoor areas	✓		✓	30–40 min	✓				✓	✓						✓	To explore, actualise, and interpret the history, mythology, and folklore of an island (immersive enquiry using silent sensory walks)
[30]	University students			✓	University campus	✓										✓	✓			✓		To evaluate the physical and perceptual dimensions of the indoor, semi-outdoor, and outdoor luminous, thermal, and auditory environment of a university campus (field measurements and questionnaire)
[22]	University students	✓			Urban spaces	✓			1 h					✓							✓	To describe/reflect the multisensory experience and personal feelings of a space (silent walk with post-walk narrative)
[26]	Researchers only; first-time visitors		✓		Small town		✓		2.5 h	✓				✓	✓							To investigate visitor experience perception of flood-damaged physical structures (phenomenological approach)
[25]	Researchers only; first-time visitors		✓		Zoo	✓				✓				✓								To examine the perception of zoo landscapes and atmospheres from the tourist perspective (phenomenological approach)
[20]	Residents, local workers, and visitors		✓		Urban spaces	✓		✓	20 min										✓			To determine what are the multisensory characteristics that people experience when using urban space (interviews and sensetalks)
[28]	Locals and urban professionals	✓		✓	Historic street	✓		✕	1 h	✓		✓					✓		✓		✓	To explore how the sensory characteristics of a street are identified/experienced by the sensory qualities (documentation of textures through digital imagery)
[23]	Workshop attendees		✓		Memorial site		✓		2 h								✓				✓	To map human actions to produce sensorial and emotional representations of places (walking and mapping)
[27]	Researchers only		✓		Urban spaces	✓				✓				✓								To develop both non-verbal and textual means as a means of recovering access to the sensory immersion experienced during a sensewalk (sensewalk and subsequent post-processing techniques)
[29]	Visual artist students	✓			Urban spaces	✓					✓											To explore how the sense of place in a contemporary city can be understood through a multisensory research framework (free methods, texture rubbing)
[18]	Childhood teachers and students			✓	Park spaces						✓											To use sensory inquiry to develop understanding about human and nonhuman intra-actions (haptic walks as an exploration of place)
[31]	Unstated			✓	Historic urban spaces	✓		✓		✓		✓				✓	✓					To explore the link between environmental quality in urban spaces and the urban microclimate (measurements and participant questionnaire)
[32]	Locals			✓	Heritage city	✓				✓		✓		✓		✓	✓				✓	To capture the sensory experience of local culture and create an understanding of heritage through the definition of sensory assets (participant questionnaire and mental mapping)

Table 1. Different methodologies identified for on-site tactile sensewalks (a cross denotes a method explicitly not employed).

Article	Participants				Site	Route				Data Collection								Data Collection Interview				Research Aims (Methodology)
	Recruitment	Solo	Duo	Group		Pre-Determined	Open	Stopping Points	Duration	Photography	Rubbings	Questionnaire	Think Aloud	Narrative	Audio Recording	Physical Measurements	Mapping	Pre Walk	During Walk	Post Walk	Post Walk Discussion/Workshop
[21]	Voluntary first-time visitors			✓	Indoor bazaar	✓				✓		✓	✓				✓	✓				To analyse the sensory stimuli experienced by participants in multiple zones of a bazaar (participants’ verbal feedback)
[19]	High-school students and local community members			✓	Multiple outdoor areas	✓		✓	30–40 min	✓				✓	✓						✓	To explore, actualise, and interpret the history, mythology, and folklore of an island (immersive enquiry using silent sensory walks)
[30]	University students			✓	University campus	✓										✓	✓			✓		To evaluate the physical and perceptual dimensions of the indoor, semi-outdoor, and outdoor luminous, thermal, and auditory environment of a university campus (field measurements and questionnaire)
[22]	University students	✓			Urban spaces	✓			1 h					✓							✓	To describe/reflect the multisensory experience and personal feelings of a space (silent walk with post-walk narrative)
[26]	Researchers only; first-time visitors		✓		Small town		✓		2.5 h	✓				✓	✓							To investigate visitor experience perception of flood-damaged physical structures (phenomenological approach)
[25]	Researchers only; first-time visitors		✓		Zoo	✓				✓				✓								To examine the perception of zoo landscapes and atmospheres from the tourist perspective (phenomenological approach)
[20]	Residents, local workers, and visitors		✓		Urban spaces	✓		✓	20 min										✓			To determine what are the multisensory characteristics that people experience when using urban space (interviews and sensetalks)
[28]	Locals and urban professionals	✓		✓	Historic street	✓		✕	1 h	✓		✓					✓		✓		✓	To explore how the sensory characteristics of a street are identified/experienced by the sensory qualities (documentation of textures through digital imagery)
[23]	Workshop attendees		✓		Memorial site		✓		2 h								✓				✓	To map human actions to produce sensorial and emotional representations of places (walking and mapping)
[27]	Researchers only		✓		Urban spaces	✓				✓				✓								To develop both non-verbal and textual means as a means of recovering access to the sensory immersion experienced during a sensewalk (sensewalk and subsequent post-processing techniques)
[29]	Visual artist students	✓			Urban spaces	✓					✓											To explore how the sense of place in a contemporary city can be understood through a multisensory research framework (free methods, texture rubbing)
[18]	Childhood teachers and students			✓	Park spaces						✓											To use sensory inquiry to develop understanding about human and nonhuman intra-actions (haptic walks as an exploration of place)
[31]	Unstated			✓	Historic urban spaces	✓		✓		✓		✓				✓	✓					To explore the link between environmental quality in urban spaces and the urban microclimate (measurements and participant questionnaire)
[32]	Locals			✓	Heritage city	✓				✓		✓		✓		✓	✓				✓	To capture the sensory experience of local culture and create an understanding of heritage through the definition of sensory assets (participant questionnaire and mental mapping)

3. Discussion

Haptic documentation through sensewalks evaluation is a relatively new field of endeavour. Research topics have been broad and include the discussion of methods and the subsequent application of touch-based sensewalking, different methodologies for collecting and processing data, and unique methods for the identification and measurement of specific haptic elements in the urban environment. A brief summary of the benefits, disadvantages, and suitability of each sensewalk method is provided below (

Table 2. Summary of the benefits, disadvantages, and suitability of each identified sensewalk method.

Sensewalk Method	Benefits	Disadvantages	Suitability
Immersive sensory enquiry (physical, narrative, map-score, and audio recording)	Allows for a deeper sensory understanding of place Awakes memory of past experience Allows for the rediscovery of familiar places Can present a ‘multisensory’ tactile record	May not provide a comparable dataset Memory benefits only suitable for local participants Narratives limited by linguistic skills	Familiarisation with the environment Realisation of local heritages Education of sensory possibilities Investigation of visitor experience
Sensetalks (interviews whilst walking)	Allows for the real-time documentation of perceptions Can include locals and non-locals for diverse insights Can provide a comparable dataset	Data response limited to the questions asked Data ultimately guided by the researcher May not allow for reflective comments	Exploration of sensory experience Exploration of sensory characteristics available Realisation of local heritages
‘Think aloud protocol’—participant thought verbalisation	Allows for the real-time documentation of perceptions Can include locals and non-locals for diverse insights Can provide a comparable dataset	Data response limited to experience of visitor Data response limited to visitor level of engagement Does not allow for reflective comments	Exploration of sensory experience Exploration of sensory characteristics available Realisation of local heritages
Multimodal post-processing techniques	Can present a ‘multisensory’ tactile record Allows for the contemplation of emotional responses Can display sensory experience meanings	Gives a record of a reflected experience, not the initial experience Output limited to the users’ imagination and experience May not provide a comparable dataset	Artistic displays/installations Education of sensory possibilities
Visualising urban textures	Can provide a comparable dataset Can record tactile features out of physical reach Straightforward implementation	May not properly realise fabricated textures Does not record other tactile parameters One-dimensional	Exploration of sensory characteristics available
Environmental measurements	Can provide a comparable dataset Can record a wide range of tactile features	Data type determined by the researcher Does not in itself allow for perceptions or experience	Exploration of correlations between physical and perceptual dimensions

).

In providing a brief summary of method suitability for research purposes, it suffices to say that the various methodologies revealed through this literature review may best be chosen to target intended research outcomes. Inductive and phenomenologically centred sensewalks would be well suited to site exploration and description rather than honing in on site characteristics, allowing for non-spatially oriented (and potentially unexpected) tactile experiences to be revealed. More structured sensewalks, such as think aloud protocols and walking interviews, are better suited to providing an understanding of a sensescape; by utilising both defined environments and (often multiple) individuals, these methods allow for the exploration of multiple perceptions of place. These methodologies also allow for tactile component mapping to varying degrees, and, therefore, a site’s spatial evaluation and the comparison of multiple sites if methodological parameters are consistently employed. Both post-processing techniques and texture visualisation have the capability to convert intangible tactile elements in a meaningful tangible manner, which can allow for sensory comparison across individual elements across multiple sites, as long as biases which occur through this kind of data facilitation are considered. Measurements are best suited for the precise documentation of tactile environmental components or the comparison of these across multiple sites, but they fundamentally lack human dimensions of experience. Measurements are also well suited for tactile mapping, both spatially and temporally.

Despite the small amount of research undertaken in this field to date, some pertinent discussion points arise. Firstly, it becomes clear that haptic components of the built environment can be strongly associated with past experience, memory, and concepts of heritage, even more so when one considers the physical act of engaging in the process of haptic investigation. As evidenced in the work of Anemogiannis and Theocharis, concentrating on a multisensory experience revealed through haptic engagement in a familiar environment allows one to attune themselves to an awareness of memory associations. Furthermore, the use of immersive enquiry allows for participants’ sensory experimentation of the surrounding environment, notably encouraging the triggering of multimodal experiences such as shaking reeds for sound generation or throwing stones to explore echo effects. In this way, a central aim of immersive enquiry is to discover new layers of sensory experience, and therefore memory, in known locations. This is echoed in the sensory enquiry work of Springgay and Truman, where engagement in haptic-based walking allowed the understanding of embodiment and place. From a methodological point of view, any distinction between the use of locals or visitors as participants in a study design should relate directly to the research question(s). To obtain grounded memory-based perception knowledge pertaining to environmental haptic components, the collection of subjective data from multiple points of view from participants with locational familiarity may be key. However, for research focusing on the perceptions of visitors (e.g., for tourism purposes), the choice of local engagement may not be considered paramount.

Such an issue becomes clear in the work of Altiparmakogullari and Hasirci, where first-time visitors of an indoor bazaar were the preferred participants. When verbalising thoughts, some participants commented that they found that jewellery shops did not fit in with the expected atmosphere of the space, with some even finding this juxtaposition of jewellery against the typical spice presentations ‘disturbing’. Clearly, these perceptions have ramifications for the identification of tactile components. How can one give a truly embodied exploration of the tactile realm if they sense that these components are unnerving or intrusive comparative to their visit expectation? Furthermore, concerning ‘locals’ versus ‘non-local’, one would have to determine how long a participant would have to live or work in a place to be actually considered ‘local’ in order to accurately distinguish between any notions of ‘familiarity’ and ‘strangeness’. This idea is somewhat echoed in studies utilising repeat visitation by non-local researchers, whereby repeat visits allow the discovery of new sensory perceptions of a space but, at the same time, are informed by previous sensory walk effects of one’s memory and experience of a space. Such an approach could provide unique datasets when creating a sensory inventory or when used to document ascribed meanings to sensory encounters.

The choice of participant selection may also be important when considering gender or social status and response effect. Research by Altiparmakogullari and Hasirci specifically chose a heterogeneous participant group, with results revealing that female participants actively engaged in touching Bazaar products (notably cotton fabrics) more so than male participants and therefore experienced a higher number of on-site tactile experiences in comparison [21]. This suggests that the inclusion of gender diversity may be paramount in research design, not only for the precise detection/recording of haptic experiences and site characteristics, but also for faithfully providing a voice to all parties when social or cultural attributes are canvassed—such as in the assessment and realisation of heritages.

Similarly, differences in Western and non-Western haptic perceptions would ultimately lead to divergent experiences and perceptions of tactile elements [33]. While this literature review is inherently limited to research written in English due to language limitations of the authors, an unexpected outcome may be that our raised awareness of currently used tactile-centred methodologies in Western cultures may generate discussion amongst scholars to further enrich these processes and procedures using non-Western philosophies.

The above can also inspire discussion regarding the use of photography or other visual means when identifying and recording tactile components. As highlighted, some studies utilised photography to capture one aspect of the tactile experience, including building surfaces and floor textures. Whilst creating a somewhat comparative documentative record of the visual perspective due to visual and haptic modalities being intertwined [34], it could be argued that other parameters are inherently lost through this process; the feel of wall temperatures, the proprioceptive feel of walking on different-textured paths, the juxtapositions of each of these across and within a space—not to mention potential issues raised for those who are visually impaired, where such a visual proxy for haptic components cannot be readily embraced. Furthermore, this method may not properly realise fabricated textures—the use of sand-cast paint on wooden buildings to emulate the more expensive real sandstone visual appeal (but with a different haptic texture) springs readily to mind. Charcoal-rubbing methods could create a comparatively stronger documentative record by giving some scale to the identified textures, allowing for the actual tactile engagement with an object within a space but leading to the possible loss of finer visual texture details. The use of visual means to record proximal haptic responses may therefore be limited to familiar objects and those connected with memory [2]. However, visual documentation does provide a relatively comparative record, and the same cannot be said for the more subjective verbal or written narratives—although these may provide a more readily contextualised and embodied account of tactile encounters. Clearly, the degree of inclusion of visual documentation should reflect the research questions.

In other studies, it becomes clear that visual documentation is paramount. Such examples include the visual record of the surrounding space to determine the true source of thermal expression. In some circumstances, building height and brick fences engendered a sense of warmth more so than direct solar heat [32], and, in others, it was the level of sky view which permitted differing magnitudes of solar energy [30]. Such photography gives an accurate record of these parameters of space and could be extended to include others such as foliage cover, building configuration for wind tunnel generation, path contours, and product layout in markets and bazaars.

An interesting theme develops through some of these works with the acceptance that an artistic slant allows for the cultivation of unusual methods. Such examples include the work of Rubidge and Stones, with the cumulative post-processing of data generating an installation-style presentation and data enhancement being a form of secondary data collection—representing not only their experience, but the subsequent meaning of the original sensory experience. Similarly, emotional responses can be uncovered through other forms of contemplation such as the use of retrospective sensory mental mapping, which has also been discussed as being effective in revealing local narratives and story making through the experience [32,35]. Such non-traditional methods may be key when attempting to actually express any haptic sensation or experience, especially as these may be difficult to articulate with our current lexicon [2].

4. Conclusions

It is clear that there is no overarching or standard method for identifying and documenting the tactile characteristics of the urban environment. The various methodologies highlighted here should be ultimately linked to a researcher’s stance and approach. However, findings from this literature review can be utilised for future research to identify preferred methodologies based on the required outcomes, using the detailed summary of the benefits, disadvantages, and suitability of each identified sensewalk method. Exemplar research methods include utilising immersive sensory enquiry approaches to reveal past experience of sensory perceptions, deeper place understandings, and the rediscovery of places; physical measurements to determine linkages and correlations between phenomena and physical and perceptual dimensions; and interviews and post-data collection reflections to explore sensory characteristics and experience and the realisation of local heritages. Practical applications of these findings can include an improved assessment of tactile-based sensewalk methodologies used across several disciplines, including the preferred utilisation of the following: physical measurements for human comfort determination in medical, educational, marketing, and tourism disciplines; immersive sensory enquiry for investigatory/exploratory research in historical and social studies and for the educational development of sensory or artistic possibilities; and interview methods for a deeper understanding of a sensescape and to identify tactile experience and the associated ascribed perceptions for cultural heritage assessments. Furthermore, a combination of methods may prove fruitful (mixed-methods approach) to allow for a more integrated approach to tactile experience examination.