Creating Usable Pin Array Tactons
for Nonvisual Information
Thomas Pietrzak, Andrew Crossan, Stephen A. Brewster, Benoıˆt Martin, and Isabelle Pecci
Abstract—Spatial information can be difficult to present to a visually impaired computer user. In this paper, we examine a new kind of
tactile cuing for nonvisual interaction as a potential solution, building on earlier work on vibrotactile Tactons. However, unlike
vibrotactile Tactons, we use a pin array to stimulate the finger tip. Here, we describe how to design static and dynamic Tactons by
defining their basic components. We then present user tests examining how easy it is to distinguish between different forms of pin
array Tactons demonstrating accurate Tacton sets to represent directions. These experiments demonstrate usable patterns for static,
wave, and blinking pin array Tacton sets for guiding a user in one of eight directions. A study is then described that shows the benefits
of structuring Tactons to convey information through multiple parameters of the signal. By using multiple independent parameters for a
Tacton, this study demonstrates that participants perceive more information through a single Tacton. Two applications using these
Tactons are then presented: a maze exploration application and an electric circuit exploration application designed for use by and
tested with visually impaired users.
Index Terms—User interfaces, human factors, haptic I/O, computer-assisted instruction.
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1 INTRODUCTION
PRESENTING information that is visually oriented to blindand visually impaired people is a challenging, but
important problem. For many educational applications or
for browsing information on the Internet, it is common to use
representations that mainly use the visual channel. For
example maps, charts, or tables present information through
the relative positions of objects. It is important for a visually
impaired person to be able to explore data where the spatial
component of the information is key to its understanding. To
allow a visually impaired user to browse spatial informa-
tion, techniques must be examined to guide them through
the data.
Here, we consider how technology can impact on this
problem. Computers are now starting to play a far greater
role in education in schools. However, computer users rely
heavily on visual feedback, with the graphical user interface
playing an important part in interactions. Users with little
or no vision must rely on other modalities to access the
same information. Screen readers, such as JAWS from
Freedom Scientific (freedomscientific.com), have proved to
be a successful solution for accessing the textual informa-
tion required to interact with a computer. Dynamic Braille
displays perform a similar function for situations where
more discreet communication is required. However, these
technologies generally only allow access in a linear manner
(from the top left corner of the screen). Further to this,
nontextual information such as pictures and diagrams are
not easily displayed in this manner. The goal of the work
described here is to examine techniques to enable users to
explore information or shapes nonvisually and navigate
computer interfaces in a nonlinear manner.
One potential solution to these problems investigated
here is to use tactile cuing to allow a visually impaired user
to browse data. Coded tactile representations such as Braille
have been used successfully for many years to transfer text
information into a nonvisual form. Tactile cues offer the
potential of a more general form of structured tactile
message to present information through the tactile channel.
To provide useful and usable tactile messages, it is
important that the user can quickly and easily distinguish
between each message to extract the contents. Here, we
describe a series of studies that examine performance in
distinguishing pin array tactile cues encoding one or many
pieces of information. At this stage of the work, we are
particularly concerned with how to present the information
in a useful manner. In particular, we will extend previous
work on Tactons [3]—structured abstract tactile messages
that encode information in the different parameters of the
tactile signal—from a vibrotactile representation to a pin
array representation. This paper describes a series of
experiments that have been conducted to examine the
appropriate design of pin array Tactons. For the purposes of
the remainder of this paper, the word Tactons will be used
to refer to pin array Tactons.
Here, we discuss these techniques from the perspective of
providing interfaces for visually impaired computer users.
Similar problems exist in situations where a sighted user has
restricted visual feedback. This could be, for example, in
mobile situations where the user is concentrating on safely
navigating a busy environment. The techniques described
here could also potentially be of use in these situations.
IEEE TRANSACTIONS ON HAPTICS, VOL. 2, NO. 2, APRIL-JUNE 2009 61
. T. Pietrzak, B. Martin, and I. Pecci are with the LITA, UFR MIM, I^le du
Saulcy, 57045 Metz, France.
E-mail: {thomas.pietrzak, benoit.martin, isabelle.pecci}@univ-metz.fr.
. A. Crossan and S.A. Brewster are with the Department of Computing
Science, University of Glasgow, 18 Lilybank Gardens, Glasgow G12 8QQ,
Scotland. E-mail: {ac, stephen}@dcs.gla.ac.uk.
Manuscript received 11 June 2008; revised 20 Feb. 2009; accepted 23 Feb.
2009; published online 17 Mar. 2009.
Recommended for acceptance by H. Noma.
For information on obtaining reprints of this article, please send e-mail to:
toh@computer.org, and reference IEEECS Log Number TH-2008-06-0040.
Digital Object Identifier no. 10.1109/ToH.2009.6.
1939-1412/09/$25.00  2009 IEEE Published by the IEEE CS, RAS, & CES