Fitts' Law and the Effects of Input Mapping and Stiffness on Flexible
Display Interactions
Input Technology
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Burstyn, Jesse
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Carrascal, Juan Pablo
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Vertegaal, Roel
Proceedings of the ACM CHI'16 Conference on Human Factors in Computing
Systems
2016-05-07
v.1
p.3649-3658
© Copyright 2016 ACM
Summary: In this paper, we report on an investigation of Fitts' law using flexible
displays. Participants performed a one-dimensional targeting task as described
by the ISO 9421-9 standard. In the experiment, we compared two methods of bend
input: position control and rate control of a cursor. Participants performed
the task with three levels of device stiffness. Results show that bend input is
highly correlated with Fitts' law for both position and rate control. Position
control produced significantly higher throughput values than rate control. Our
experiment also revealed that, when the amount of force applied was controlled,
device stiffness did not have a significant effect on performance.
An Evaluation of Shape Changes for Conveying Emotions
Shape Changing Displays
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Strohmeier, Paul
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Carrascal, Juan Pablo
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Cheng, Bernard
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Meban, Margaret
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Vertegaal, Roel
Proceedings of the ACM CHI'16 Conference on Human Factors in Computing
Systems
2016-05-07
v.1
p.3781-3792
© Copyright 2016 ACM
Summary: In this paper, we explore how shape changing interfaces might be used to
communicate emotions. We present two studies, one that investigates which
shapes users might create with a 2D flexible surface, and one that studies the
efficacy of the resulting shapes in conveying a set of basic emotions. Results
suggest that shape parameters are correlated to the positive or negative
character of an emotion, while parameters related to movement are correlated
with arousal level. In several cases, symbolic shape expressions based on clear
visual metaphors were used. Results from our second experiment suggest
participants were able to recognize emotions given a shape with a good accuracy
within 28% of the dimensions of the Circumplex Model. We conclude that shape
and shape changes of a 2D flexible surface indeed appear able to convey
emotions in a way that is worthy of future exploration.
What can Doodles on the Arm teach us about On-Body Interaction?
Late-Breaking Works: Novel Interactions
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Strohmeier, Paul
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Carrascal, Juan Pablo
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Hornbæk, Kasper
Extended Abstracts of the ACM CHI'16 Conference on Human Factors in
Computing Systems
2016-05-07
v.2
p.2726-2735
© Copyright 2016 ACM
Summary: The use of the skin as interaction surface is gaining popularity in the HCI
community. To offer an alternative perspective on how we might design on-body
interactions, we conducted a questionnaire asking if, how, and why people mark
their skin. We found that visibility and ease of access were important factors
for choosing to mark the body. We also found that while some participants
consider marking the body as a private activity, most participants perceive
such markings as a public display. This tension between the personal nature of
on-body interaction and the skin as a public display, as well as hedonic uses
of body markings, present interesting design challenges.
MagicWand: Exploring Physical Affordances with a Handheld Cylindrical
Display Object
Interactivity Demos
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Priyadarshana, Lahiru Lakmal
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Porter, Victoria
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Carrascal, Juan Pablo
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Visser, Aaron
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Vertegaal, Roel
Extended Abstracts of the ACM CHI'16 Conference on Human Factors in
Computing Systems
2016-05-07
v.2
p.3762-3765
© Copyright 2016 ACM
Summary: We introduce MagicWand, a cylindrical handheld display object made out of 2
Flexible Organic Light-Emitting Diode (FOLED) screens. Magic Wand features a
smartphone running the Android operating system. Gesture recognition allows
movements of the wand as a form of input. We were interested in exploring how a
cylindrical form factor might offer physical affordances for action that are
quite different from those of a traditional flat smartphone. We present an
application scenario where MagicWand is used as a game controller that can
display a variety of 3D game elements.
ReFlex: A Flexible Smartphone with Active Haptic Feedback for Bend Input
Keep In Shape
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Strohmeier, Paul
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Burstyn, Jesse
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Carrascal, Juan Pablo
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Levesque, Vincent
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Vertegaal, Roel
Proceedings of the 2016 International Conference on Tangible and Embedded
Interaction
2016-02-14
p.185-192
© Copyright 2016 ACM
Summary: ReFlex is a flexible smartphone with bend input and active haptic feedback.
ReFlex's features allow the introduction of sensations such as friction or
resistance. We report results from an experiment using ReFlex in a targeting
task, as well as initial users' reactions to the prototype. We explore both
absolute and relative tactile haptic feedback, paired with two types of bend
input mappings: position-control and rate-control. We observed that
position-controlled cursors paired well with relative bend feedback, while
rate-controlled cursors paired well with absolute bend feedback to indicate
targets. We also explored an eyes-free condition. Results suggest that while
eyes-free, haptic feedback conditions were more error-prone than visual-only
conditions, the size of the error was relatively small, and users were able to
complete the task in all cases. We present two application scenarios that take
advantage of the unique input and output modalities of ReFlex and discuss its
potential for within document navigation.
An In-Situ Study of Mobile App & Mobile Search Interactions
Understanding Everyday Use of Mobile Phones
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Carrascal, Juan Pablo
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Church, Karen
Proceedings of the ACM CHI'15 Conference on Human Factors in Computing
Systems
2015-04-18
v.1
p.2739-2748
© Copyright 2015 ACM
Summary: When trying to satisfy an information need, smartphone users frequently
transition from mobile search engines to mobile apps and vice versa. However,
little is known about the nature of these transitions nor how mobile search and
mobile apps interact. We report on a 2-week, mixed-method study involving 18
Android users, where we collected real-world mobile search and mobile app usage
data alongside subjective insights on why certain interactions between apps and
mobile search occur. Our results show that when people engage with mobile
search they tend to interact with more mobile apps and for longer durations. We
found that certain categories of apps are used more intensely alongside mobile
search. Furthermore we found differences in app usage before and after mobile
search and show how mobile app interactions can both prompt mobile search and
enable users to take action. We conclude with a discussion on what these
patterns mean for mobile search and how we might design mobile search
experiences that take these app interactions into account.
Towards effective ethical behavior design
Works-in-progress
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de Oliveira, Rodrigo
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Carrascal, Juan Pablo
Proceedings of ACM CHI 2014 Conference on Human Factors in Computing Systems
2014-04-26
v.2
p.2149-2154
© Copyright 2014 ACM
Summary: Many of today's persuasive systems are designed taking into account
cognitive biases to foster positive changes in people's behavior (e.g. adopt
greener attitudes). However, these biases are also exploited to shape the
users' behavior in a way that not necessarily benefit them (e.g. user retention
in a website). Scholars addressed this problem by developing design guidelines
and methods for ethics in persuasive computing, but these approaches alone have
proved to be inefficient since they require every designer to be aware,
understand, and comply with the recommended ethical practices. We propose
preventive approaches that shall support higher compliance, as well as a
remediation-based approach that does not require compliance from every
designer. These approaches aim to help users understand persuasive elements
embedded in systems, as well as to take more rational decisions when
interacting with them. We expect that using preventive and remediation-based
approaches will more effectively implement ethics in behavior design.
Your browsing behavior for a big mac: economics of personal information
online
Research papers
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Carrascal, Juan Pablo
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Riederer, Christopher
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Erramilli, Vijay
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Cherubini, Mauro
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de Oliveira, Rodrigo
Proceedings of the 2013 International Conference on the World Wide Web
2013-05-13
v.1
p.189-200
© Copyright 2013 ACM
Summary: Most online service providers offer free services to users and in part,
these services collect and monetize personally identifiable information (PII),
primarily via targeted advertisements. Against this backdrop of economic
exploitation of PII, it is vital to understand the value that users put to
their own PII. Although studies have tried to discover how users value their
privacy, little is known about how users value their PII while browsing, or the
exploitation of their PII. Extracting valuations of PII from users is
non-trivial -- surveys cannot be relied on as they do not gather information of
the context where PII is being released, thus reducing validity of answers. In
this work, we rely on refined Experience Sampling -- a data collection method
that probes users to valuate their PII at the time and place where it was
generated in order to minimize retrospective recall and hence increase
measurement validity. For obtaining an honest valuation of PII, we use a
reverse second price auction. We developed a web browser plugin and had 168
users -- living in Spain -- install and use this plugin for 2 weeks in order to
extract valuations of PII in different contexts.
We found that users value items of their online browsing history for about
€7 (~10USD), and they give higher valuations to their offline PII, such as
age and address (about 25€ or 36USD). When it comes to PII shared in
specific online services, users value information pertaining to financial
transactions and social network interactions more than activities like search
and shopping. No significant distinction was found between valuations of
different quantities of PII (e.g. one vs. 10 search keywords), but deviation
was found between types of PII (e.g. photos vs. keywords). Finally, the users'
preferred goods for exchanging their PII included money and improvements in
service, followed by getting more free services and targeted advertisements.
A note paper on note-taking: understanding annotations of mobile phone calls
Patterns of use
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Carrascal, Juan Pablo
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de Oliveira, Rodrigo
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Cherubini, Mauro
Proceedings of the 14th Conference on Human-computer interaction with mobile
devices and services
2012-09-21
p.21-24
© Copyright 2012 ACM
Summary: Note-taking has been largely studied in contexts of work meetings. However,
often people need to remember information exchanged in informal situations,
such as during mobile phone conversations. In this paper we present a study
conducted with 59 subjects who had their phone calls semi-automatically
transcribed for later annotation. Analysis of the 621 calls and the subjects'
annotation behavior revealed that phone recall is indeed a relevant user need.
Furthermore, identifying patterns in phone calls such as numbers and names
provide better indicators of annotation than variables related to the callers'
profile, context of calls, or quality of service. Our findings suggest
implications for the design of mobile phone annotation tools.
Multitouch Interface for Audio Mixing
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Carrascal, Juan P.
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Jordà, Sergi
NIME 2011: New Interfaces for Musical Expression
2011-05-30
p.100-103
Keywords: audio mixing, multitouch, control surface, touchscreen
© Copyright 2011 Authors
Summary: Audio mixing is the adjustment of relative volumes, panning and other
parameters corresponding to different sound sources, in order to create a
technically and aesthetically adequate sound sum. To do this, audio engineers
employ "panpots" and faders, the standard controls in audio mixers. The design
of such devices has remained practically unchanged for decades since their
introduction. At the time, no usability studies seem to have been conducted on
such devices, so one could question if they are really optimized for the task
they are meant for. This paper proposes a new set of controls that might be
used to simplify and/or improve the performance of audio mixing tasks, taking
into account the spatial characteristics of modern mixing technologies such as
surround and 3D audio and making use of multitouch interface technologies. A
preliminary usability test has shown promising results.
BitDrones: Towards Levitating Programmable Matter Using Interactive 3D
Quadcopter Displays
Demonstrations
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Rubens, Calvin
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Braley, Sean
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Gomes, Antonio
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Goc, Daniel
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Zhang, Xujing
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Carrascal, Juan Pablo
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Vertegaal, Roel
Adjunct Proceedings of the 2015 ACM Symposium on User Interface Software and
Technology
2005-11-08
v.2
p.57-58
© Copyright 2005 ACM
Summary: In this paper, we present BitDrones, a platform for the construction of
interactive 3D displays that utilize nano quadcopters as self-levitating
tangible building blocks. Our prototype is a first step towards supporting
interactive mid-air, tangible experiences with physical interaction techniques
through multiple building blocks capable of physically representing interactive
3D data.
