Distinguishability of similars. Usability increases when Sara is able to distinguish among similar item features.
Where a sighted user distinguishes
similar features, such as among the
buttons on a CD player or CD cases in
a collection, due to written labels on
the items or by seeing each item’s position in a larger spatial context, Sara
had much more difficulty. She labeled
items in Braille that were otherwise
difficult to distinguish and used her
hands, fingers, feet, nose, and ears to
see what her eyes could not. Each opportunity for sensing and distinguishing can be exploited by technology
designers. Design that aids identification and distinguishability of otherwise similar features, such as CD cases
with preprinted Braille identifiers and
cellphone keys with textured surfaces,
enhances ease of use, flexibility, and
efficiency. Sara showed how, with deft
fingers, she is able to distinguish differ-ent-size measuring cups held together
by a common ring. She complained
that some cellphones lacked keys she
could identify by touch.
Brute-force backup. One fallback
problem-solving technique is to exhaustively try all possibilities. When
Sara became disoriented while demonstrating her Language Master and
JAWS software, she tried all possible
options as much as possible. Due to
her self-described disorganization, her
linear search method for CDs is the
most effective tactic, but also very time-consuming.
Flexibility and interoperability. Sara
took notes and read books on her
BrailleNote, but her model lacks external storage, except for a floppy drive,
and does not include access to the Internet. By considering how people will
use particular devices when carrying
out larger task landscapes,
14 such as
that Sara might not only want to take
class notes but share these notes with
friends using the Internet, designers
increase opportunities for use. Despite the many uses of her BrailleNote,
Sara wanted a laptop computer due to
its flexibility for Internet access, communication, and storage.
conclusion
We draw two main conclusions from
the study. The first is methodological.
We used an ethnographically inspired
simply replacing
one interaction
mode, such as
the display of text
on a screen with
a functionally
equivalent mode,
as in speaking
the text aloud, is
not necessarily
equivalent from
the point of view
of user experience.
investigation of a single, nonsighted
individual interactions with a variety of artifacts in her own home. Our
concern with not only usability but socially situated meaning contrasts with
experimental designs focused on measurement and control and with lab-based usability studies. Although we
can state our conclusions as principles
associated with this individual’s preferences and beliefs, such statements
are animated in the ways in which we
observed them. We are unsurprised
that, for instance, Sara’s sense of self
is intimately tied to her relationships
in her social network. How could it
not be? We are, however, surprised in
the specific ways in which this was embedded in her choices about artifacts
and interactions. Such surprise—in
her wall of textually labeled photographs as conversation pieces for her
sighted friends, her preference for a
tactile watch because of how it looks
and feels, and the use, when she was
a child, of her talking dictionary as
an ice-breaker with friends—
undoubtedly reflects our situatedness
(as researchers and as people) within
our own social worlds, the taken-for-granted assumptions we carry with us
as sighted people.
To what extent are we able to generalize these results to other contexts
and other people? Though single-per-son case studies are rare in human-computer interaction, they have a long
history in the social and behavioral
sciences. For example, studies with
single participants that have been influential were undertaken by Freud in
psychoanalysis,
7 Harper in sociology,
9
and Luria in brain/mind studies.
12 One
goal of case-study research is to develop theoretical propositions that can
be used to guide subsequent research
studies and design efforts. However,
it is important to understand the difference between these analytic generalizations and the statistical generalizations common in experimental
study designs. Emphasizing this distinction, Yin24 writes, “‘How can you
generalize from a single case?’... The
short answer is that case studies, like
experiments, are generalizable to theoretical propositions and not to populations or universes. In this sense, the
case study, like the experiment, does
not represent a ‘sample,’ and in doing