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code into the the web page. Initial user testing to-
gether with informal feedback during a demo session
has confirmed acceptance and learnability. However,
in this paper we assess more closely the usability, per-
formance and practical implications of this approach
and thus focus on:
1. Description of design and functionality of the
framework and its interface.
2. Head-to-head comparison of the OHW’s perfor-
mance against normal, non-enhanced operation.
3. Discussion of its suitability for different types of
websites based on its implementation into popular
sites.
4. Overall discussion of the OHW as a tool for one-
handed website operation on touchscreen smart-
phones.
2 PREVIOUS RESEARCH
When designing thumb-friendly interfaces, Wob-
brock et al. (Wobbrock et al., 2008) suggest sup-
porting and evoking horizontal thumb movements as
much as possible, as vertical movements were found
to be overly challenging. On this basis they sug-
gest a horizontal layout of interactive elements on
the screen to accommodate the economic peculiari-
ties of the thumb and improve usability. Katre (Ka-
tre, 2010) shows that a curved arrangement of ele-
ments on a touchscreen is perceived as comfortable
and easy, as it supports a more natural circular motion
of the thumb. An application of this is found in inter-
faces such as ArchMenu (Huot and Lecolinet, 2007)
or ThumbMenu, where the user moves their thumb
over an arch of elements placed in the bottom right
corner of the screen.
Other researchers have explored the use of con-
centric menus such as the Wavelet menu (Francone
et al., 2010) and SAM (Bonnet and Appert, 2011) to
enhance thumb-based interaction, similar to the first
generation Apple iPod. In the case of the Wavelet
menu, research has shown that this approach with its
consistent interaction model is easy to learn and ef-
ficient to use. L
¨
u and Li (L
¨
u and Li, 2011) present
Gesture Avatar where the user can highlight a GUI el-
ement on screen to gain better control of it via an en-
larged avatar. While this is an innovative way of im-
proving one-handed device operation, it requires the
user to draw their interface first, depends on a pro-
prietary application and cannot be customised by the
webmaster.
In terms of general adaptation of websites for mo-
bile devices, one approach is web page segmenta-
tion (Hattori et al., 2007; Gupta et al., 2007), using
a proxy server to re-render the page into new logical
units which are subsequently served to the device. A
proprietary solution is the Read4Me browser (Yu and
Miller, 2011) where the browser offers to optimise the
page for mobile display via a proxy-server that then
serves it to the user. Bandelloni et al. suggest a differ-
ent system (Bandelloni et al., 2005) where the devel-
oper creates an abstract XML-based description of the
layout and a proxy server renders the information for
the respective access device. In addition to these tech-
niques, various services, themes and frameworks exist
to adapt websites for mobile devices and CSS3 media
queries offer a flexible approach for display adapta-
tion.
While existing approaches are all concerned with
the display of a website on mobile devices, the OHW
addresses a so-far neglected aspect: the specific sup-
port of one-handed operation of the web page. By
implementing the OHW into a website, improvements
are made to the operation – rather than the presenta-
tion – of the site, as this remains problematic even on
well-adapted sites when operating it with one hand.
Most importantly, the enhancement is done at runtime
and on the client, can be fully configured by the web-
master and is dependent only on the browser itself and
the user, who can choose to switch the enhancements
on or off at any time.
3 METHODOLOGY
To verify the findings of previous researchers (Katre,
2010; Wobbrock et al., 2008) promoting a curved in-
terface for thumb-based GUIs, we conducted a small
user study with 7 participants (3 F, mean age 31.43
years, SD 4.65), all of who declared to be frequent
users of touchscreen mobile devices. Participants
were asked to swipe 10 times using their right and
left thumb without looking at the device. They were
instructed to swipe in a way that was most natural and
comfortable to them, avoiding bending and stretching
of the joints. Traces of these swipes were recorded on
a hidden layer and saved. Stacking the resulting im-
ages on top of each other shows the curved movement
created by a horizontal swipe, supporting the findings
of previous researchers and informing our design of
the interface (Fig. 1). To develop and verify our de-
sign, we iteratively tested paper prototypes with users
to transform the wheel menu metaphor into a com-
prehensive website interface, supporting a more nat-
ural operation and minimal strain. Building on dis-
cussions with web developers, we made the OHW as
non-intrusive and supportive as possible in the form of
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