The Warmth of a Prosthetic Arm: Sincerity, Appearance and the Freedom to Be Left Alone
Reflections on prosthetic design, the uncanny valley, social perception, technical reliability and the unexpected meanings of warmth.
What does warmth have to do with a prosthetic arm?
Graham Pullin, Professor of Design and Disability at the University of Dundee, recently asked me an interesting question while apparently working on his book The Warmth of Hands and Voices: Design, Disability and Technology [link to it once it appears]. The details of that text are of course confidential.
But my own consideration of warmth is not, because it reaches above that book itself.
Could I identify any sense of warmth in my long and satisfying relationship with the prosthetic arms, hands, hooks and grippers that I have adopted, modified and appropriated over the years? It is an interesting question because warmth in a colloquial sense is not something I have particularly sought in a prosthesis. Quite the contrary, and if only from a superficial view.
My priorities have been reliability, mechanical precision, low maintenance, durability, affordability and, perhaps most importantly, the ability to go about my day without my prosthetic arm becoming the centre of attention. Yet there may be a connection between warmth and prosthetics that is less obvious than the familiar associations of softness, human likeness, friendliness and emotional attachment: that of sincerity. While a colloquial as well as my nonprofessional connotation of warmth would suggest the aforementioned aspects, sincerity is an aspect of warmth under a sociologically defined construct and thus under a more professionally structured view.
So, a relevant particular aspect of warmth, as understood in the psychological stereotype content model or SCM, is sincerity. Its opposite thus includes dishonesty, insincerity and unkindness [or, say, plagiarism], and not just “being cold” or “standoffish” and so on. And sincerity, it turns out, describes rather well what I have been trying to also achieve with my prosthetic arm for almost two decades, particularly in a visual and technical way.
A meeting with another upper extremity limb different person: skin-coloured hands and a red Becker hand
Around 2008 or 2009, I met one guy who worked as psychology professor. at a local prosthetic clinic during a demonstration of the then-new i-Limb myoelectric hand. At the time, that guy was enthusiastic about his Otto Bock myoelectric hand and particularly proud of its highly realistic, skin-coloured cosmetic glove. He explained that, as a professor, he considered a convincingly human-looking prosthesis important for being taken seriously professionally.
Already then, I had taken a somewhat different approach. I was using a body-powered Becker hand, a mechanically operated device with a remarkably useful combination of precision grip, adaptive grip and power grip. It was reliable, comparatively affordable and mechanically straightforward. At the time, one could obtain a Becker hand directly from its manufacturer for approximately USD 650.
I had also developed a bright red cover for it. Both the mechanical capabilities of the Becker hand and its deliberately conspicuous red appearance seemed to surprise that guy. We discussed the matter extensively over a consumable downtown.
The red hand had an interesting effect: it simultaneously attracted attention and made the prosthesis seemingly disappear from other people’s attention. Its appearance was so obviously intentional and so clearly not an attempt to imitate human anatomy that people seemed able to accept and recognise that without needing to investigate further. My declaration of disability and of orthopedic support had the honesty of a traffic redlight, proverbially and in any other sense.
That guy subsequently also became interested in non-skin-coloured prosthetic appearances. He wanted an i-Limb. And as things went, later, he appeared on numerous television programmes promoting the i-Limb with a non human appearance, and became publicly associated with the emerging image of the technologically augmented amputee. His subsequent research also touched directly on the question of warmth and the stereotypes associated with people using prosthetic limbs such as being a cyborg: link to relevant psychology publication.
One issue we had discussed at the time was the tendency of other people to make assumptions about amputees’ intellectual abilities. Visible physical disability can trigger assumptions about competence that have no factual basis. In the stereotype content model or SCM, warmth and competence are separate dimensions of social perception. A person may be perceived as warm but less competent, or competent but less warm. The appearance of a prosthetic device may influence such judgments before a conversation has even begun.
That brings us to an important distinction: a prosthesis may appear friendly, warm or human-like without necessarily being sincere about what it actually is. There are also warm and friendly academics that seem all nice and then they steal ideas, images. Not all, but they existed I heard.
The problem with prosthetic marketing and brand ambassadors
The i-Limb era also introduced me to another super important aspect of sincerity: the difference between what prosthetic devices promise and what they actually deliver. Myoelectric prosthetic hands are often advertised through impressive demonstrations, carefully selected photographs, videos and enthusiastic testimonials. The technology can look extraordinary, particularly to people who have never worn a prosthesis. However, a medical device manufacturer is constrained by regulatory requirements, including CE marking and medical device legislation. Claims about performance and safety must be substantiated. Of course we have real problems there, that too [link]. So manufacturers like themselves some brand ambassadors. You see, brand ambassadors and enthusiastic users, on the other hand, and as opposed to the companies themselves, can make claims that may go considerably further than the manufacturer’s official documentation. I have seen demonstrations of people swimming with myoelectric hands even though the relevant device instructions prohibit water sports. Such imagery creates expectations that may be completely disconnected from the manufacturer’s actual operating limits. I was told privately that some prominent brand ambassadors / promoters hardly wore their prostheses in everyday life. That is not something I can independently establish for every individual, but the distinction between promotional performance and actual daily use remains even more important.
To no surprise, amputee support groups contain numerous accounts of users who were disappointed after discovering that expensive bionic hands did not provide the practical improvements they had expected. My own prosthetist has complained over the years that these expensive devices have not sold nearly as well as their promotional appeal might suggest, while some users have been furious about the limited practical improvement they experienced after weeks or months.
This is where sincerity becomes a particularly important concept. A prosthesis should not have to tell a flattering story about itself. It should do what it claims to do, and do it reliably. And any visual aspect it has, carries that with it.
A prosthesis that does not demand attention
My family, friends and wife have never been particularly interested in what my prosthetic arm looks like. They care whether it works. And that is precisely what I wanted. A prosthesis should be like comfortable shoes, a reliable jacket or a good wristwatch: an everyday object that performs its function without constantly requiring attention, explanation, maintenance or emotional investment.
I did not want a prosthesis to become the defining subject of every meeting or conversation. For someone with a visible disability, repeated questions can become tedious. The first few conversations may be interesting. The hundredth or thousandth repetition is another matter entirely. People differ in how they experience this. Some enjoy the attention. I do not particularly want it. When my wife and I first got together, she thought I might be exaggerating the problem. Then, during restaurant visits, waitresses repeatedly focused on my prosthetic arm and tried to initiate the usual rewind-play conversations about it. After several dinners interrupted in this way, she understood. The prosthesis seemingly had become a social invitation that I had never issued.
I wanted to eliminate that invitation without having to explain myself. Over time, I discovered that the more obviously technical, industrial and unambiguously prosthetic my arm looked, the less people asked. With my present setup, I have not experienced those restaurant encounters for more than a decade. Even while teaching international forensic imaging courses to many different groups over the years, virtually nobody has asked about my prosthetic arm. That is a remarkable improvement in everyday life. The device communicates its purpose immediately. It is visibly a technical solution for an arm amputee, not a concealed human hand, a mystery to solve or an invitation to discuss disability.
In that sense, its appearance is sincere.
The uncanny valley, a printed necktie and people who cannot quite see all that well
One of the most useful lessons about appearance came from an entirely different “experiment”. Occasionally, I would attend professional conferences wearing a suit jacket over a T-shirt with a necktie printed on it. The effect was amusing. Some colleagues immediately recognised that as a fashion joke and smiled. A very few seemed irritated because the outfit violated their expectations of professional dress. More interestingly, a few people apparently could not visually distinguish the printed tie from a real one at a distance of several metres and were upset then. They would see something that looked almost correct but not quite. The initially blurred visual information however did not fit their expectations, and they became surprisingly irritated. The printed-tie experiment demonstrated how imperfect perception could combine with social expectations to create a kind of visually triggered cognitive dissonance. The observer sees something that is nearly familiar, but cannot immediately resolve the discrepancy.
This reminded me of Masahiro Mori’s concept of the uncanny valley. The phenomenon is particularly relevant to prosthetic hands. A close relative once described her reaction to my skin-coloured prosthetic hand in striking detail: her eyes detected that something was wrong, but she could not immediately identify what it was, and so then her attention automatically became involuntarily fixed on the object, trying to frantically resolve the visual puzzle. The process happened before she could consciously decide to ignore it. And she said that felt super distressing.
Other people independently reported similar reactions. They found skin-coloured or partly human-looking prosthetic hands irritating, even when they cognitively understood perfectly well what they were seeing. I experimented with different appearances: dark ebony-like wood, piano black, bright red and various other finishes, but even small distractions, small aspects of cultural meaning, distorting the semiotics of my prosthetic arm, would cause a mild or moderate distortion in my otherwise relaxed vibe field, so to say. I could sometimes walk into the cafeteria at work and almost immediately sense how the particular device I was wearing affected the people around me. The more obviously mechanical the prosthesis, the less apparent cognitive conflict it produced.
The most relaxed reactions that I got consistently occurred when my device looked entirely technical, with no suggestion that it might be anything other than a mechanical prosthesis. Most sincere, and sincere in its design to be seen even across a hallway or a large room, allowing for others that do not see that well to also be included in that type of visual sincerity. Today, my prosthetic arm looks worn, technical and unmistakably prosthetic. People are friendly, and nobody seems particularly concerned.
The engineering of sincerity
Over the years, I have made numerous small technical modifications to my prosthetic arm. None of these would qualify as a revolutionary breakthrough. They are the kind of incremental improvements that are almost invisible in technological marketing but enormously important in daily use. An additional plastic deflection roller prevents the steel operating cable from abrading against surrounding components. The roller that fitted best happened to be orange, so I subsequently found matching PVC tubing to give the arrangement some minimal visual consistency. A taped-down pin lock, additional cable guides and other small changes contribute to reliability and component longevity. Steel and carbon fibre acquire scratches and lose their original gloss, but they can remain structurally sound for many years. As the weak points were progressively eliminated, the prosthesis stopped requiring frequent repairs. I no longer needed a new socket every few years when the parts did stay in place rather than falling off. Some of the problems I eliminated struck me as examples of planned obsolescence, or at least design choices that unnecessarily shortened the useful life of components. The prosthesis gradually became a genuinely ordinary everyday object. Its appearance developed almost accidentally, through practical modifications rather than a deliberate aesthetic programme. Interestingly, the result resembles a certain industrial, urban and almost dystopian design language. Having been born in Munich and raised in different places, I found myself drawn to the work of fashion designer Boris Bidjan Saberi. Others have remarked that this style fits my otherwise utilitarian appearance.
But the prosthesis was not designed to imitate fashion. Its aesthetic emerged from function. An orange roller was orange because that was the component that fitted. Matching tubing followed. Scratched metal remained scratched because polishing it would serve no practical purpose. This raises an interesting question about identity. Rather than asking whether a prosthesis reflects an already established image of myself, perhaps the question is whether I am willing to let my appearance evolve through the devices and modifications that actually work.
Why I stopped decorating my prosthesis
There was a time when I experimented extensively with appearance. I considered colours, surface finishes, decorative elements, printed designs and other forms of personalisation. Eventually, I stopped. The reason was not that I had discovered the perfect appearance. It was that further experimentation no longer offered enough practical benefit. A coloured hook will eventually become scratched and require repainting or replacement. A bare metal hook can simply remain scratched. Silicone and PVC covers wear out. Decorative finishes deteriorate. Every additional component introduces another potential maintenance task.
The more things I could remove, the less work the prosthesis required. The result was an almost uncompromising form of visual sincerity. It looks like what it is. There is no attempt to disguise its function, soften its identity or make it resemble something else. And perhaps that is why it works so well socially.
Warmth in actual human contact
There is another, more literal interpretation of warmth: physical intimacy, touch and human contact. Here the answer is quite straightforward. My wife, friends and I generally prefer that I do not wear a prosthesis when physical contact matters. I have spent a great deal of time swimming, and I still swim occasionally. In the water, with little more than swimming trunks and goggles, a prosthesis has no particular role. At home, I usually remove the prosthesis whenever I do not need it. In private life, it can simply get in the way. There is no reason to attribute projected emotional or tactile warmth to a mechanical device that is unnecessary in those situations.
Some friends have explicitly said that they do not regard the prosthesis as part of me. Several prefer the straightforward appearance of technical hooks and grippers to artificial skin-coloured hands. For them, too, the mechanical appearance seems more comfortable. I do not generally describe my glasses, wristwatch or other everyday equipment as warm or cold. They are objects that perform particular functions. My prosthetic arm belongs largely to the same category.
The warmth, when present, belongs to the human relationship rather than to the equipment.
The end-of-day feeling: my practical measure of success
One of the most important criteria for a prosthesis is rarely represented in advertisements or laboratory demonstrations. How do I feel at the end of the day? A prosthesis may perform impressively in a short demonstration but become exhausting over eight or ten hours of actual use. Its practical value accumulates through hundreds of small interactions. How often does something slip? How many times does a mobile phone fall? What happens when a camera drops for the third time? How often must I adjust the device, repair something or interrupt an activity? The cumulative effect is what I think of as the End of Day Feeling.
Wearing one device for a week or month and then another for a similar period can produce quite different results, even if their technical specifications appear comparable. For nearly two decades, mechanical hooks, the V2P prehensor and similar body-powered devices have consistently provided the best results for me. Staring is one thing, but it is not necessarily the most important thing. Dropping expensive or delicate objects repeatedly is a much more substantial problem. A device that works reliably, avoids social friction and leaves me relaxed at the end of the day is successful. A device that looks spectacular but produces frustration is not.
The unexpectedly friendly TRS Jaws
Over the years, the TRS Jaws gripper has attracted more positive comments and compliments than almost any other terminal device I have worn. The Jaws has a somewhat friendly shape. It resembles, in a loose way, the gripping hand of a Lego figure. It is still clearly mechanical, but its proportions and rounded appearance seem to make it approachable. I am not certain whether I would describe this as warmth. Nevertheless, there may be something about its shape that people find pleasant.
I have also used a foil cutter to make large smiley stickers, and people responded positively when I wore one. These experiences suggest that there may be ways to introduce friendliness into prosthetic design without resorting to human imitation. A prosthetic gripper does not need artificial skin to be approachable.
The TRS Jaws also has substantial practical advantages. Bob Radocy developed the Jaws range, including the XFS version with its particularly strong spring. That model is excellent for activities such as cycling. Its usefulness and its appearance are not in conflict. Perhaps that combination is more interesting than trying to make a prosthesis look human.
The fur-covered hand that never quite happened
One of my more unusual projects remains unfinished. For a while, I very much wanted to make a fur-covered prosthetic hand. The idea was to sew real cowhide, with the fur attached, onto the back or extensor side of a normal nitrile work glove fitted over my Becker hand. I did not want artificial fur or a synthetic imitation. I wanted actual animal hide. The resulting appearance would have been something between human, animal and mechanical prosthesis.
I imagined calling it half Wolf, half animal. It would certainly have violated conventional expectations about what a prosthetic hand ought to look like. But it would also have introduced an entirely different tactile and visual quality from polished metal, plastic or artificial human skin. Perhaps that would have been warm in some sense. It would almost certainly have invited conversations again, something I had otherwise worked hard to avoid. I actually cut the fur and began stitching it onto a glove. Then the project stalled. The partly completed hand is still somewhere in my cellar among other unfinished experiments.
Maybe one day I will finish it. It is an interesting contradiction: after spending years eliminating unnecessary social attention, I was considering a prosthesis almost guaranteed to attract it. But the difference is that such attention would be invited deliberately, on my own terms.
The difference between photographs and living with a prosthesis
Discussions of prosthetic appearance often rely heavily on still photographs. This is a serious limitation. A prosthesis is not a static sculpture. It is worn by a moving person, interacting with objects, performing tasks and participating in ordinary life. The visual impression of a device in a photograph can differ profoundly from the impression it produces in use.
A particularly striking example is the Krukenberg procedure, in which the forearm is surgically separated into two functional segments that can provide a gripping mechanism. In still photographs, the resulting appearance is sometimes described in extremely negative terms, even as grotesque or disfiguring. Yet the experience of seeing someone use such an arm in real life can be entirely different. The movement, functional capability and obvious usefulness transform the impression. What initially looks strange in a photograph can become perfectly comprehensible when observed in action. I have written about this distinction between how prosthetic devices are seen and experienced: see my discussion of prosthetic appearance and perception
There is also an important difference between how the wearer experiences a device and how observers perceive it. The wearer experiences weight, grip security, control, comfort, durability and fatigue. The observer may primarily notice shape, colour, novelty or resemblance to a human hand. These are different forms of information. Marketing frequently exploits the observer’s perspective, while the user must live with the practical consequences.
A spectacular photograph can sell an idea. It cannot demonstrate years of dependable daily use.
Is warmth really the goal?
Returning to Graham Pullin’s question, I am not convinced that warmth, in the conventional sense, is a particularly useful primary design objective for my prosthetic arm. I do not need the device to look human, evoke affection or reassure other people through artificial skin.
I need it to work, to last, to be affordable, to avoid unnecessary maintenance and to communicate clearly what it is. But sincerity is maybe a priority in any other forms of warmth. A device that is honest about its nature and capabilities, that does not pretend to be something else, and that does not demand attention may create a more relaxed social environment than a supposedly friendly imitation of a human hand.
There may also be room for playful, expressive alternatives: a red Becker hand, a smiling TRS Jaws, or perhaps even my unfinished fur-covered hand. The important distinction is between appearance imposed by social expectations and appearance chosen by the person who actually uses the device. A prosthesis need not be visually warm to support a satisfying life. It may be enough for it to be mechanically reliable, visually unambiguous and socially unobtrusive.
And there is a final paradox here. The more completely my prosthesis has become an ordinary, unremarkable technical object, the less attention it requires from me and everyone around me. That leaves more time and energy for everything else: work, cycling, swimming, friendships, intimacy, experimentation and ordinary daily life. Perhaps the ultimate warmth of a prosthesis is not something located in the device itself. Perhaps it is the freedom it gives us to forget about the device altogether.
And perhaps my unfinished fur hand, sitting somewhere in the cellar, represents a remaining possibility: that one day I might deliberately choose warmth, humour or extravagance again, not because society expects it, but simply because I feel like it.
C. G. Jung, psychological projection and the perceived coldness of prosthetic hooks
There is another dimension to this that I find particularly interesting, namely C. G. Jung’s concept of psychological projection.
In Jungian psychology, projection describes the process by which people unconsciously attribute aspects of their own psychological life, including fears, conflicts and disowned characteristics, to another person or object.
A prosthetic hook may provide a particularly powerful surface for such projections. Its bare metal, exposed mechanics, sharp contours and unmistakably non-human appearance can evoke associations with coldness, aggression, emotional detachment or even psychological disturbance. Popular culture has reinforced these associations for decades, frequently equipping villains, pirates, sinister characters and psychologically disturbed figures with hooks or other conspicuous bodily differences.
Yet, were we to be responsible adults, none of these characteristics belongs to the actual wearer or follows from the true mechanical properties of the device. The hook is simply a highly effective, robust, affordable and reliable gripping tool. The observer may nevertheless unconsciously interpret the absence of a human-looking hand as the absence of human warmth, or mistake a deliberately functional appearance for evidence of a cold, threatening or mentally deranged personality.
From a Jungian perspective, one might argue that the observer is encountering not so much the amputee as aspects of their own psychological imagery, perhaps even what Jung called the shadow: those disturbing or socially unacceptable qualities that a person finds difficult to recognise in themselves.
This is an interpretation, of course, not a demonstrated psychological mechanism specific to prosthetic hooks.
But it raises an interesting possibility: the perceived coldness of a prosthesis may reveal considerably more about the observer than about the person wearing it. There is also an important paradox.
A mechanically sincere, unambiguously technical hook may initially invite negative projections, yet its ordinary, competent use in everyday life can undermine them. Once people see the wearer handling a camera, riding a bicycle, working or simply enjoying a conversation, the threatening symbolism may give way to the much less dramatic reality of an ordinary person using a practical tool.
The warmth was never absent from the person; it was the observer’s interpretation of the device that obscured it. So ultimately our society may have to face that academics as a general field attracts a considerable number of people that act out anxiety and fear and simply projects their views on us [e.g. link, link, link, link, etc.].
