Hi everyone. My name is Marie Mühlhaus and I am a PhD student at Saarland University.
Today, I present "FeatherHair: Interacting with Sensorized Hair in Public Settings".
This is a joint work I did together with Jürgen Steimle and Marion Koelle.
The body as an interaction space has long fascinated HCI researchers.
And in this space, hair is especially compelling because of its exposed
position on the body and its unique physical affordances since it is soft and malleable.
Prior work has contributed first interactive hair prototypes using capacitive sensing.
Notable examples here include, e.g., Vega et al's HairWare and Dierk et al's HairIÖ.
However, so far none of these works has been taken into account a field deployment,
as capacitive sensing is not robust enough for diverse and ever-changing everyday context,
including, for example, wind, moisture or incidental touch.
But crucially, hair has high socio-cultural significance.
Thus, we need to take our prototypes into the field. And only then we can fully evaluate and understand
user expectations towards interactive hair. And with FeatherHair we address this challenge.
So, Featherhair is a gesture-controlled hair interface that is suitable for field deployment.
In our pictorial, we contribute: First, a fabrication process for sensorized hair,
and a robust, hybrid sensing technique which is suitable for outdoor, everyday environments.
Second, we contribute insights from evaluating FeatherHair in diverse social contexts, and design implications
for future, socially acceptable and usable hair interfaces.
FeatherHair consists of several strands of off-the-shelf feather hair extensions that we sensorized to enable
various input gestures. And it combines capacitive and piezoresistive touch sensing.
And with this hybrid approach, we can enable robust gesture recognition.
Our proof-of-concept prototype consists of three strands of sensorized feathers connected to a microcontoller.
To robustly detect gestural input, capacitive and resistive measurements are obtained through spatial multiplexing.
And to sensorize our feathers, we used in-situ polymerization.
So, in-situ polymerisation is a chemical treatment that was introduced by Honnet et al. and it causes
conductive polymers to form in and around the feathers barbs and barbules. The feather
is now conductive, but retains its tactile qualities. So, when pressed or stroked, the
downy structure of the feather causes a change in resistivity as the polymers compress.
So, our feather hair extension shows piezo-resistive behavior.
For capacitive sensing along the full length of the feather, we wrapped the feather's shaft with a 0.035 mm
thin conductive thread. Also, we created solderable connectors to connect our piezo-resistive and capacitive
feather sensors to the microcontoller. You can find the details in our pictorial.
To turn our sensorized feather extensions into functional and interactive hair, we implemented
a gesture recognition routine using a random forest classifier. We trained this classifier
for a data set consisting of five gestures: These include tap, doubletap, hold, slide, and twirl.
In total, we collected 3074 gesture samples from 10 participants and trained a
user-independent gesture recognition model on all five gestures. However, to boost the
recognition accuracy for our field study, we eliminated twirl from our set of gestures,
as it turned out to be prone to noise. In the end, this resulted then in a final system
accuracy of around 89% which we found to be reliable enough to conduct our field study.
We detail more about our data collection procedure and the implementation in our pictorial and
you can also access the dataset and the trained model in our GitHub repository.
Evaluating hair interfaces in actual social context is crucial, as hair itself is social.
To this end, we designed a field experiment for FeatherHair where participants followed a walking route across campus.
During the study, they wore and interacted with FeatherHair while crossing various social contexts such as
populated public outdoor areas, busy bus stops , quiet indoor and outdoor locations, or, for example, the university cafeteria.
Also, we split the walking route into 3 parts. First, the participant was accompanied by the experimenter in a guided
walk. Here, the experimenter prompted the participants to perform specific gestures
at specific locations and directly afterwards, the experimenter asked the participant in a
conversation-like manner about how they felt performing the gesture in the specific social context.
To eliminate a potential bias of the experimenter's presence, we also included
an unguided segment where the participant did the interaction with our prototype without
the researcher’s presence. At the end of the route, they met again and the participant
could report their experiences. The last third of the route again consisted of a guided walk. Here,
the participants were allowed to freely explore any further interactions with FeatherHair that
they could think of, but they were also encouraged to reflect on further appearance- or interaction-related
aspects that were not yet covered in the prior parts of the walk.
Afterward, we analyzed the audio recordings of these conversations inductively using a combination of
qualitative content analysis and a semantic thematic analysis. With that, we can include both pragmatic, usability
related aspects in our discussion, but also more subjective and experiential aspects.
Taking FeatherHair to the field allowed us to synthesize four major design implications
that are specific to interacting with hair interfaces in public settings. And these implications
cover wearability, suitable gestures, diverse users and social context. In the following,
I detail on some key findings for each area, but please refer to our pictorial for the complete overview.
Key in terms of wearability is that naturalness needs to be balanced against
discoverability. Because we observed that the more the interface feels like real hair
– which is a desirable property-, the more difficult it actually becomes to distinguish
it from real hair – which is a required property. And in turn, this limits the usability
of the interface. As a remedy, we suggest to selectively adding passive haptic landmarks to
the sensorized hair. These can help to guide the users interactions without altering the
overall hair-like structure. In public settings, users often desire unobtrusive interactions.
For interactions with hair these are flowing movement patterns such as sliding or twirling. They
occur naturally and for that reason, they are unobtrusive and intuitive. Since they
are also familiar to the user, they result in a decreased cognitive load. However, these
naturally occurring gestures are also more likely to be misinterpreted by others and
also to cause false activations. Thus, when designing gestures for hair interfaces, it
is crucial to consider in which contexts and for which tasks the gestures should be
used. For critical tasks, for instance, such as calling the police, unnatural gestures
such as a long hold might be more favorable as they do not occur incidentally and feel probably
also more reliable to the user.
Hair is as diverse as users are. So, gestures such as
twirling or sliding are not applicable for short or very long hair. Similarly, how suitable
a form factor or an attachment method is depends on the individual structure of the user's
hair. In addition, participants in our user study pointed out how not only their gender
but also other aspects of their identity shaped their expectations toward hair interfaces,
for instance, regarding the aesthetics of it. And the implication for designers is that
the interface cannot be a one-type-fits-all device but rather should be a tailor-made
device that is tailored towards the needs and expectations of a more specific and closely
defined group of users. The main goal of our research was to evaluate a hair interface
in actual social context. One of the most important things that we found here is that
the social acceptance of an hair interface largely depends on the specific context in
which it is used. So even within our relatively short walk on campus, differences between
different social contexts were revealed: So, for example, the more involved a user was
in a conversation or interaction with another person, the more inacceptable the interaction
with technology becomes - even if it is disguised as a naturally occurring and familiar
gesture. Touching or twirling one's hair amidst a conversations is also commonly considered a
sign of mental absentness or insecurity, independently from whether there is technology
that you are interacting with or not. On the other hand, for situations where the user is not the focus of
attention, we were able to show that interactions with hair can be convenient, intuitive and socially
acceptable. In summary, we argue that a hair interface should not be designed for a general purpose but
each designed for one primary social context in which it shall be deployed. In summary,
our work contributes a fabrication approach for a gesture-controlled hair interface which
is robust enough to be deployed in the field. We show how to combine the unique haptic affordances
of off-the-shelf feather hair extensions with hybrid touch sensing. And finally, we also
contribute design implications that are specific to interactive hair and that will allow to
make interactive hair less disruptive and more usable, while also accounting for bodily diversity
and social influence. If you have any questions, feel free to reach out via e-mail and
don't forget to check out our pictorial. Enjoy and thanks for watching!