**3. Haptic interface design**

The main focus of haptic technology development is to produce higher resolution and higher fidelity of actuators that improve simulation quality. Applications of this technology give designers versatility to conjure immersive realities or surrealities. The electrotactile feedback to simulate virtual walls [15] is a literal representation of reality; projects like the electromagnetic shoes simulating dynamic gravity [16] offer other worldly realities. There are also unique haptic interfaces allow for very specialized applications, such as Microsoft's HapticLink, a bimanual controllers [17] that are connected and can simulate stiffness of operating twohanded objects (i.e., operating keys of an instrument, shooting a bow, etc.). Wearable haptic device like the Microsoft's Claw [18] and EXIII's Exos wrist DK [19] both use servos to provide resistance to your palm and fingers to "touch" digital shapes.

Specialized embodiments of the design, like dynamically deformable surfaces (i.e., ForceForm) can vary in stiffness (simulate lumps, indents) to facilitate telepresence diagnosis [20].

Rather than simulating reality, "haptic special effect" are similar to sound effects in movies. The Star Wars lightsaber sounds, which have no real world counterpart, are recorded with metal wires slapping against a hard surface. When paired with appropriate visual and/or auditory stimuli, haptic illusions can be very compelling. The iconic cutaneous bunny-hop illusion involves several point source of tactile actuators on a subject's arm; when triggered in sequence, the brain's change bias combines the separate sources into one moving source [21]. An evolution of the illusion, the "/ed" (slashed) project by Watanabe et al. creates the illusion of being sliced in half with haptic feedback coupled with seeing a fake sword slash [22]. Speakers in front of the subject triggers, followed by those on the back, giving the subject a sensation of object passing through the body.

The gaming industry makes use of haptic illusions to supplement their gameplay. REZ's Synesthesia suit uses vibrotactile feedback to enhance the psychedelic visual and auditory gaming experience [23]. The overload of multi-modal stimulation is suitable in the context of the game. The KOR-FX haptic vest recreates a reduced version of bullet impact [24]. Disney Research's haptic chair does not reproduce the sensation of driving, but its vibrotactile actuators can influence and possibly supplement the spatial awareness of the player [25].

The elderly are found to be more receptive toward haptic than visual interfaces [26]. Since the first graphic user interface appeared, the windows, icons, menus, and pointing device (WIMP) design has not changed. All current GUIs are derivatives of the original concept and build off of users' prior experience with them. It is possible that as the part of the population that grew up with technology and are familiar computing esthetics age, this will change. For the currently and imminently senior population, metaphorical UI and association with tangible objects from real life are much more approachable [27]. Immersive simulations can offer a new life for those with reduced mobility. "Second-life" platforms are making a comeback as a result of VR technology [28]. Through design and improvements in technology, immersion can be powerful enough to trigger our body image plasticity that allows for remapping of motor controls and development of new habits. From remapping of existing nerves to operate a prosthetic arm [29], to EEG-enabled direct brain-computer interaction by a monkey [30], the brain demonstrates profound adaptivity in reaction to the new interfaces.

Neuroplasticity and increase in brain matter have been observed in elderly subjects tasked with learning a new motor skill for 90 days (juggling & navigation games) [31], with apparent delay of Alzheimer's [32]. These improvements, however, were seen to disappear after 90 days of inactivity, implying the need for continued intervention [31]. Therefore, the design of interfaces that accompany the elderly need to be engaging enough for continued usage, or risk atrophy and difficulties in relearning. In the following sections, we will present some key characteristics to designing haptic interfaces for the elderly with diminishing cognitive and motor functions.

#### **3.1. Animacy**

We believe that the only limitation to immersive simulations are the quality of actuators. Mimicking reality is therefore not the focus of this chapter. Instead, we will discuss creative applications of haptic interfaces in terms of the types of experiences they allow for, given the technological constraints. Most of these fall under "haptic illusions" that our sensorium constructs. As a researcher, creating these powerful haptic experiences is most often a process

Our experience of haptic information in the real world is almost always coupled with other senses, predominantly vision and proprioception. Haptic sensation itself is also vibration [12], same as audition. By connecting spatial information and haptic sensation, the tactile nature of the target is generated internally. The discovery of frequency nature of haptic stimuli, we are able to create better simulations drawn from reality. Recording and playing back textures for example has a wide range of applications from more immersive telepresence and VR experiences to very specialized utility tools for designers [9]. However, in designing tactile displays, the goal need not be to reproduce known phenomenon; the brain can learn and adapt to new interfaces with new intentions. Simplest forms of haptic interfaces of binary activation (ON or OFF) is easiest to learn. By augmenting this information temporally and/or spatially, much more complicated information can be sent to the brain. In the case of sensory substitution, Eagleman Lab showed that the deaf can make use of temporal–spatial, vibrotactile stimuli to decipher auditory input of spoken words [13]. Similar methodology applied on abstract datasets, such as stock market [14], further supports the power of neuroplasticity to adapt.

The main focus of haptic technology development is to produce higher resolution and higher fidelity of actuators that improve simulation quality. Applications of this technology give designers versatility to conjure immersive realities or surrealities. The electrotactile feedback to simulate virtual walls [15] is a literal representation of reality; projects like the electromagnetic shoes simulating dynamic gravity [16] offer other worldly realities. There are also unique haptic interfaces allow for very specialized applications, such as Microsoft's HapticLink, a bimanual controllers [17] that are connected and can simulate stiffness of operating twohanded objects (i.e., operating keys of an instrument, shooting a bow, etc.). Wearable haptic device like the Microsoft's Claw [18] and EXIII's Exos wrist DK [19] both use servos to pro-

Specialized embodiments of the design, like dynamically deformable surfaces (i.e., ForceForm)

Rather than simulating reality, "haptic special effect" are similar to sound effects in movies. The Star Wars lightsaber sounds, which have no real world counterpart, are recorded with metal wires slapping against a hard surface. When paired with appropriate visual and/or auditory stimuli, haptic illusions can be very compelling. The iconic cutaneous bunny-hop illusion involves several point source of tactile actuators on a subject's arm; when triggered in sequence, the brain's change bias combines the separate sources into one moving source

can vary in stiffness (simulate lumps, indents) to facilitate telepresence diagnosis [20].

vide resistance to your palm and fingers to "touch" digital shapes.

of discovering an existing neurological phenomenon.

54 Assistive Technologies in Smart Cities

**3. Haptic interface design**

Animacy is a subcategory of Immersion that deserves highlighting. If Immersion can be seen as providing enough information to make a simulation compelling, then Animacy is conveying enough information to make sentient elements believable or imbue traits of sentience. Tactile information is crucial to the expression of emotion in humans and animals [34], and to the formation of social bonds [35]. We can even form these intimate bonds with inanimate objects when the right stimuli are present; symphonic musicians respond emotionally to the haptic feedback from their instruments [36].

Social isolation and sedentarism are becoming more rampant. As the population ages alongside this shift, the elderly are more likely to be living independently and in isolated situations. Reduced mobility lead to reduced social interactions, so telepresence communication is becoming the dominant way for comprehensive communication. While our information infrastructure make this possible already, a larger amount of data can be designed into the interaction to enhance the Animacy of the communication partner. One study shows that haptic stimuli provided in conjunction with audio clips of conversations enhanced our perception of the conversations' qualities (more animate, pleasant, warm, etc.) [37]. However, the influence of the stimuli is not reported by the participants, despite observed differences when compared to a control group [37]. Similarly, the inclusion of haptic qualities of a conversation in telecommunication is often overlooked when designing immersive experiences, despite their powerfully persuasive effects. Essential to the conveying sense of emotional intensity and Animacy, haptic telepresence, or mediated touch, is a crucial piece of telepresence technology [38].

vibration [43]. User feedback for Pebble confirmed a sense of animacy and presence of their partners. Interestingly, the users combined their knowledge of the partners with the device. For instance, when the Pebble is outside the range of internet and stops transmitting, the receiver could tell their partner had entered the subway and felt reassurance when the signal re-appeared [43]. Reassurance does not have to come from a human source; Keio University's Nene projects uses a soft robot avatar of the participants' pets to study effect of haptic telepresence on loneliness [44]. The pet cats' or dogs' body temperature is reproduced in the doll, as are the sounds they make; purring is translated to vibration sensations. Compared to the control group, subjects report a decrease in loneliness over the 2 weeks of usage. The thermal, auditory, and vibrotactile stimuli produced a sense of Animacy and presence of the pet, which had a calming effect on the subjects [44]. It would be interesting to investigate whether the existence of a real-world source of the stimuli is crucial to the calming effect, or that an algorithm generated simulation of the pet is enough. The following section will

Creative Haptic Interface Design for the Aging Population

http://dx.doi.org/10.5772/intechopen.78991

57

Physical and cognitive impairments are rising alongside the growing life expectancies of an aging population. Visual and auditory deficiencies affect the sufferer's ability to engage with much of the predominated infrastructures. Deterioration of cognitive and motor skills mean that the elderly have lowered independence and mobility, leading to decreased quality of life. Technology driven solutions in virtual reality (i.e., Rendever) and artificial intelligence [45] can mitigate some of these problems, but their designs likewise underrepresented this demographic. Virtual reality in particular offer advantages for the elderly: (1) simplified, safe, simulated space for learning, therapy, and exploration, (2) adaptive, responsive modalities based on user's requirements and preferences. Comparable to solutions for people with disabilities or autism, these technological interventions for the elderly face the challenge of dealing with minority population of extreme or unique users. Thus, one solution is not enough for the variety of contexts, but bespoke solutions are costly. Affordances in the design of UI for

Just as visual and auditory VR have shown to help with people with physical [46], sensorial [47], and cognitive [48] disabilities, haptic feedback enhances activities like rehabilitation, learning, and behavioral change. Stroke victims regaining motion benefit from visual and haptic feedback in their training process [46]. Memory retention and information acquisition is enhanced by

Redundancy is a powerful tool in designing UI for extreme users. Especially for novel UI elements, redundant conveyance through multiple modalities can make learning easier. In the conditions that they work, jet pilots require haptic feedback in order to effectively operate their vehicles [50]. Haptic helmets and chairs are used to offer a level of redundant information on the state of their aircraft when the other senses (proprioception, vision, audition) are unreliable or unavailable. Elderly users can benefit from a similar technique of redundancy to supplement their diminishing senses: navigation for the blind through a haptic belt [51], and for the elderly through augmented reality [11] are some examples. Movement rehabilitation

haptic layer of redundancy, as we found in our work on multi-modal reading [49].

discuss telepresence therapy and design for elderly in more detail.

these technologies can have life changing impacts.

**3.2. Affordance**

CASPER by Tokyo University effectively uses haptic telepresence (air-cannon) to transmit instructor's touches to parts of the participant's body; some of the participants of the experiments noted that they could feel the presence of the instructor there with them [8]. Some elderly participants even shared their desire to have remote interactions with family and friends through the device [8]. By successfully capturing Animacy through mediated touch, we can mitigate the problems caused by social isolationism and sedentarism. These solutions can also be easily augmented onto existing platforms and other modalities.

Daily interpersonal communication make use of physical contact to convey and receive haptic sensations that inform on the emotional state and animacy of others. Rigid correlation between stimuli and resulting abstract feelings has not been drawn, but the presence, not the content, of haptic stimuli reveal a non-trivial impact on the quality of communication [37]. Nevertheless, we have found that temperature, pressure and frequency of haptic outputs are important characteristics to triggering emotional responses in the user. Changes to initial body temperature affect subjects' emotional response measured with skin conductance response (SCR); higher ratings of arousal and dominance are reported with contact to a pre-adjusted temperature source than through dynamically adjusting the contact to a target temperature [37]. The same study suggests that warmer or colder stimuli do not matter, while other literature suggests warmer stimuli are associated with pleasantness [39, 40]. A larger range of temperature thresholds is necessary to trigger avoidance and approach behaviors. Pressure is a common modality for conveying emotion, such as its use to comfort children with autism [33]. Temporally supplied stimulation is another powerful indicator: with low frequency of feedback are linked to stronger feelings of intimacy, and higher frequencies correlate to anxiety. Commercial devices such as Doppel have been built under the premise that our body's rhythms can be influenced by an external stimulus. Doppel operates by vibrating at particular frequencies that appear to influence wearer's heart rate [41].

Haptic feedback in telepresence situations offer unique interactions to capture non-verbal communications. Haptic pajamas that allow parents to remotely hug their children [42]. The Pebble smartwatch transmits intensity of activity (body motion) between two people through vibration [43]. User feedback for Pebble confirmed a sense of animacy and presence of their partners. Interestingly, the users combined their knowledge of the partners with the device. For instance, when the Pebble is outside the range of internet and stops transmitting, the receiver could tell their partner had entered the subway and felt reassurance when the signal re-appeared [43]. Reassurance does not have to come from a human source; Keio University's Nene projects uses a soft robot avatar of the participants' pets to study effect of haptic telepresence on loneliness [44]. The pet cats' or dogs' body temperature is reproduced in the doll, as are the sounds they make; purring is translated to vibration sensations. Compared to the control group, subjects report a decrease in loneliness over the 2 weeks of usage. The thermal, auditory, and vibrotactile stimuli produced a sense of Animacy and presence of the pet, which had a calming effect on the subjects [44]. It would be interesting to investigate whether the existence of a real-world source of the stimuli is crucial to the calming effect, or that an algorithm generated simulation of the pet is enough. The following section will discuss telepresence therapy and design for elderly in more detail.

#### **3.2. Affordance**

Social isolation and sedentarism are becoming more rampant. As the population ages alongside this shift, the elderly are more likely to be living independently and in isolated situations. Reduced mobility lead to reduced social interactions, so telepresence communication is becoming the dominant way for comprehensive communication. While our information infrastructure make this possible already, a larger amount of data can be designed into the interaction to enhance the Animacy of the communication partner. One study shows that haptic stimuli provided in conjunction with audio clips of conversations enhanced our perception of the conversations' qualities (more animate, pleasant, warm, etc.) [37]. However, the influence of the stimuli is not reported by the participants, despite observed differences when compared to a control group [37]. Similarly, the inclusion of haptic qualities of a conversation in telecommunication is often overlooked when designing immersive experiences, despite their powerfully persuasive effects. Essential to the conveying sense of emotional intensity and Animacy, haptic telepresence, or mediated touch, is a crucial piece of telepresence technology [38].

CASPER by Tokyo University effectively uses haptic telepresence (air-cannon) to transmit instructor's touches to parts of the participant's body; some of the participants of the experiments noted that they could feel the presence of the instructor there with them [8]. Some elderly participants even shared their desire to have remote interactions with family and friends through the device [8]. By successfully capturing Animacy through mediated touch, we can mitigate the problems caused by social isolationism and sedentarism. These solutions

Daily interpersonal communication make use of physical contact to convey and receive haptic sensations that inform on the emotional state and animacy of others. Rigid correlation between stimuli and resulting abstract feelings has not been drawn, but the presence, not the content, of haptic stimuli reveal a non-trivial impact on the quality of communication [37]. Nevertheless, we have found that temperature, pressure and frequency of haptic outputs are important characteristics to triggering emotional responses in the user. Changes to initial body temperature affect subjects' emotional response measured with skin conductance response (SCR); higher ratings of arousal and dominance are reported with contact to a pre-adjusted temperature source than through dynamically adjusting the contact to a target temperature [37]. The same study suggests that warmer or colder stimuli do not matter, while other literature suggests warmer stimuli are associated with pleasantness [39, 40]. A larger range of temperature thresholds is necessary to trigger avoidance and approach behaviors. Pressure is a common modality for conveying emotion, such as its use to comfort children with autism [33]. Temporally supplied stimulation is another powerful indicator: with low frequency of feedback are linked to stronger feelings of intimacy, and higher frequencies correlate to anxiety. Commercial devices such as Doppel have been built under the premise that our body's rhythms can be influenced by an external stimulus. Doppel operates by vibrating at particular frequencies that appear to influence wearer's

Haptic feedback in telepresence situations offer unique interactions to capture non-verbal communications. Haptic pajamas that allow parents to remotely hug their children [42]. The Pebble smartwatch transmits intensity of activity (body motion) between two people through

can also be easily augmented onto existing platforms and other modalities.

heart rate [41].

56 Assistive Technologies in Smart Cities

Physical and cognitive impairments are rising alongside the growing life expectancies of an aging population. Visual and auditory deficiencies affect the sufferer's ability to engage with much of the predominated infrastructures. Deterioration of cognitive and motor skills mean that the elderly have lowered independence and mobility, leading to decreased quality of life. Technology driven solutions in virtual reality (i.e., Rendever) and artificial intelligence [45] can mitigate some of these problems, but their designs likewise underrepresented this demographic. Virtual reality in particular offer advantages for the elderly: (1) simplified, safe, simulated space for learning, therapy, and exploration, (2) adaptive, responsive modalities based on user's requirements and preferences. Comparable to solutions for people with disabilities or autism, these technological interventions for the elderly face the challenge of dealing with minority population of extreme or unique users. Thus, one solution is not enough for the variety of contexts, but bespoke solutions are costly. Affordances in the design of UI for these technologies can have life changing impacts.

Just as visual and auditory VR have shown to help with people with physical [46], sensorial [47], and cognitive [48] disabilities, haptic feedback enhances activities like rehabilitation, learning, and behavioral change. Stroke victims regaining motion benefit from visual and haptic feedback in their training process [46]. Memory retention and information acquisition is enhanced by haptic layer of redundancy, as we found in our work on multi-modal reading [49].

Redundancy is a powerful tool in designing UI for extreme users. Especially for novel UI elements, redundant conveyance through multiple modalities can make learning easier. In the conditions that they work, jet pilots require haptic feedback in order to effectively operate their vehicles [50]. Haptic helmets and chairs are used to offer a level of redundant information on the state of their aircraft when the other senses (proprioception, vision, audition) are unreliable or unavailable. Elderly users can benefit from a similar technique of redundancy to supplement their diminishing senses: navigation for the blind through a haptic belt [51], and for the elderly through augmented reality [11] are some examples. Movement rehabilitation [8] and motor skill learning especially benefit from the haptic feedback. However, the designer needs to be conscious of the different needs and offer affordances in their product for the extreme users.

analogies from culture and psychology are more reliable starting points than established UI

Creative Haptic Interface Design for the Aging Population

http://dx.doi.org/10.5772/intechopen.78991

59

Social learning is the theory that we observe and learn from others' behavior. Our mental model of another's mind and action help us inform our own. Therefore, collective, group learning is another useful technique for reducing the familiarity curve. Keio University Fujisawa et al. experimented with a group of participants learning to operate artificial tails [58]. Some group of participants were allowed to communicate with each other and share their discoveries. In those groups, the experiment identified a cascade effect in which proficiency rapidly spread through all participants when a single individual discovers a

All technology can malfunction. The results of malfunction or failures in systems we heavily rely upon can cause detrimental results for the user. In the case of telepresence devices that are linked to the user's partner (Pebble) or pets (Nene), a severed connection can cause unnecessary stress over their perceived condition. Reviews for the commercial devices like the BOND bracelet that allow users to send "touches" to a partner is a good example of technical failure causing severe emotional responses [59]. Designers need to clearly indicate to the user of system failure rather than something catastrophic on the other end of the telepresence. If the BOND bracelet could have informed the user the difference between a problem with the app or device and a problem with the partner, customers may be more forgiving with technical difficulties. More serious cases of technology that enable certain actions or aide motion require special attention: unexpected failures in haptic feedback in devices helping the elderly with activities like maintaining balance or navigation can have dangerous consequences. Fail-

One of the greatest barriers to the proliferation of this technology is the diversity of extreme user needs. Variations in body types and deficiencies require bespoke and often singular solutions, thus significantly increase the costs for development. The field of prosthetics design for the physically disabled face a similar problem. Body type difference and varying needs means one design cannot have full coverage. Techniques like crowdsourcing and rapid-prototyping have been a boon for prosthetics design and can likewise be useful for haptic interfaces. Developers of products should look upstream, prior to the actual usage, to implement ways

In the case of prosthetics, makers are creating bespoke solutions from off the shelf components [60]. Open-sourced platforms (i.e., OpenBionics, Open Hand Project) provide editable templates for 3D printing. Prototypes for haptic research often use the same fabrication methods, powered by the same open-source electronics platforms, like Arduino and Raspberry Pi. Modular, DIY electronics components and kits for wearable technology have promising overlaps with creating personalized haptic interfaces, allowing users to tailor the solution to

design practices.

breakthrough.

*3.2.2. Malfunctions and failures*

safes must be implemented prior to unsupervised usage.

*3.2.3. Personalization and diversity of needs*

to grant wider access for extreme users.

The term "Affordance" arose from psychology and later adopted by HCI as the consistency between possible actions and the user's perception of the possibilities. Dan Norman expanded on the definition in his book "*The Design of Everyday Things*" [52] to perceived versus real affordances. Unlike the perceived affordances of GUI design for visual displays, real affordances do not require the user to have a preconceived notion about an element's function. Visual interfaces in our products often build off of user's prior digital literacy and familiarity. A graphical representation of a button requires you to understand the nature of its real world counterpart; a dropdown menu is a mutation of the button that do not have a physical analog to draw prior knowledge from. For the elderly and extreme users, we should not design with reliance on domain-specific conventions and consistencies, which they may have neither the familiarity with nor the capability of using. Our interview with elderly PACE participants in the United States reveal their preference of Kindle over smart-tablet devices because of the former's affordances for viewing content, yet apps for the elderly are still predominantly on the latter. We highlight three main challenges for the elderly subjects to using haptic interfaces, which can be overcome with Affordances designed into the device.

#### *3.2.1. Learning/familiarity curve*

The most challenging aspect of learning a new haptic interfaces is need to experience the interface first-hand; an intellectual demo is often not enough. Instead, the user must try it out, which also adds difficulty for the iterative design process. The learning curve can be lowered through design. By taking advantage of our instincts and other senses, we can encode haptic information in intuitable ways. For instance, animals and insects make use of the haptic sense to construct their mental model of the world around them [53]. Biomimetic design for sensory augmentation such as Tokyo University's Haptic Radar demonstrates the effectiveness of intuitive haptic stimuli to trigger responses with no training [54]. The radar is a good example of affordance due to its simplicity: haptic feedback equates to the presence of an obstacle which triggers user reaction. There is alternative interpretation possible. A notable product for the elderly that achieves this are the emergency alert devices (i.e., MobileHelp, Lifeline). It is a simple button that transmits a signal to the emergency response facilities; particularly useful for the elderly in independent-living situations, the device allows for only singular purpose that is intuitable even when the user is confused or in duress.

Inspired by the mnemonic device of "memory palaces" in cognitive psychology [55], we created a virtual reality memory box, Keepsake, to explore the retrieval of memory using spatial coordinates around the user [56]. The association of a life event with a general direction relative to the body was a preferable alternative to the linear timeline of most graphic displays. Likewise, physical objects enhance recall: asking an elderly subject to recount memories regarding a souvenir have much more detailed responses than without the physical aide [57]. Metaphorical UIs are powerful tools for guiding intuition, as long as the users are already familiar the metaphor. In the context of design for extreme users and technologically illiterate, analogies from culture and psychology are more reliable starting points than established UI design practices.

Social learning is the theory that we observe and learn from others' behavior. Our mental model of another's mind and action help us inform our own. Therefore, collective, group learning is another useful technique for reducing the familiarity curve. Keio University Fujisawa et al. experimented with a group of participants learning to operate artificial tails [58]. Some group of participants were allowed to communicate with each other and share their discoveries. In those groups, the experiment identified a cascade effect in which proficiency rapidly spread through all participants when a single individual discovers a breakthrough.

#### *3.2.2. Malfunctions and failures*

[8] and motor skill learning especially benefit from the haptic feedback. However, the designer needs to be conscious of the different needs and offer affordances in their product for the

The term "Affordance" arose from psychology and later adopted by HCI as the consistency between possible actions and the user's perception of the possibilities. Dan Norman expanded on the definition in his book "*The Design of Everyday Things*" [52] to perceived versus real affordances. Unlike the perceived affordances of GUI design for visual displays, real affordances do not require the user to have a preconceived notion about an element's function. Visual interfaces in our products often build off of user's prior digital literacy and familiarity. A graphical representation of a button requires you to understand the nature of its real world counterpart; a dropdown menu is a mutation of the button that do not have a physical analog to draw prior knowledge from. For the elderly and extreme users, we should not design with reliance on domain-specific conventions and consistencies, which they may have neither the familiarity with nor the capability of using. Our interview with elderly PACE participants in the United States reveal their preference of Kindle over smart-tablet devices because of the former's affordances for viewing content, yet apps for the elderly are still predominantly on the latter. We highlight three main challenges for the elderly subjects to using haptic inter-

The most challenging aspect of learning a new haptic interfaces is need to experience the interface first-hand; an intellectual demo is often not enough. Instead, the user must try it out, which also adds difficulty for the iterative design process. The learning curve can be lowered through design. By taking advantage of our instincts and other senses, we can encode haptic information in intuitable ways. For instance, animals and insects make use of the haptic sense to construct their mental model of the world around them [53]. Biomimetic design for sensory augmentation such as Tokyo University's Haptic Radar demonstrates the effectiveness of intuitive haptic stimuli to trigger responses with no training [54]. The radar is a good example of affordance due to its simplicity: haptic feedback equates to the presence of an obstacle which triggers user reaction. There is alternative interpretation possible. A notable product for the elderly that achieves this are the emergency alert devices (i.e., MobileHelp, Lifeline). It is a simple button that transmits a signal to the emergency response facilities; particularly useful for the elderly in independent-living situations, the device allows for only singular

Inspired by the mnemonic device of "memory palaces" in cognitive psychology [55], we created a virtual reality memory box, Keepsake, to explore the retrieval of memory using spatial coordinates around the user [56]. The association of a life event with a general direction relative to the body was a preferable alternative to the linear timeline of most graphic displays. Likewise, physical objects enhance recall: asking an elderly subject to recount memories regarding a souvenir have much more detailed responses than without the physical aide [57]. Metaphorical UIs are powerful tools for guiding intuition, as long as the users are already familiar the metaphor. In the context of design for extreme users and technologically illiterate,

faces, which can be overcome with Affordances designed into the device.

purpose that is intuitable even when the user is confused or in duress.

extreme users.

58 Assistive Technologies in Smart Cities

*3.2.1. Learning/familiarity curve*

All technology can malfunction. The results of malfunction or failures in systems we heavily rely upon can cause detrimental results for the user. In the case of telepresence devices that are linked to the user's partner (Pebble) or pets (Nene), a severed connection can cause unnecessary stress over their perceived condition. Reviews for the commercial devices like the BOND bracelet that allow users to send "touches" to a partner is a good example of technical failure causing severe emotional responses [59]. Designers need to clearly indicate to the user of system failure rather than something catastrophic on the other end of the telepresence. If the BOND bracelet could have informed the user the difference between a problem with the app or device and a problem with the partner, customers may be more forgiving with technical difficulties. More serious cases of technology that enable certain actions or aide motion require special attention: unexpected failures in haptic feedback in devices helping the elderly with activities like maintaining balance or navigation can have dangerous consequences. Failsafes must be implemented prior to unsupervised usage.

#### *3.2.3. Personalization and diversity of needs*

One of the greatest barriers to the proliferation of this technology is the diversity of extreme user needs. Variations in body types and deficiencies require bespoke and often singular solutions, thus significantly increase the costs for development. The field of prosthetics design for the physically disabled face a similar problem. Body type difference and varying needs means one design cannot have full coverage. Techniques like crowdsourcing and rapid-prototyping have been a boon for prosthetics design and can likewise be useful for haptic interfaces. Developers of products should look upstream, prior to the actual usage, to implement ways to grant wider access for extreme users.

In the case of prosthetics, makers are creating bespoke solutions from off the shelf components [60]. Open-sourced platforms (i.e., OpenBionics, Open Hand Project) provide editable templates for 3D printing. Prototypes for haptic research often use the same fabrication methods, powered by the same open-source electronics platforms, like Arduino and Raspberry Pi. Modular, DIY electronics components and kits for wearable technology have promising overlaps with creating personalized haptic interfaces, allowing users to tailor the solution to their unique needs. Manufacturers have created custom boards and components for haptic applications [61]. However, this development technique still has a technical barrier to entry.

Crowdsourcing design is a promising method to overcome this barrier. Adjustable templates and modular components can enable the democratization of design, so individual solutions can be generated as iterations off of the original. These design features need to be intentional and customization perceivable by the users as intended by its creator.
