effect on cognitive performance. As shown in Figure 1, starting from a baseline of normal, increasing the degree of a condition leads to an increase in cognitive performance (in mathematics, logic, multitasking, creativity, etc.). As the performance rises, so do the negatives, until they peak. A decline follows, until the mix of giftedness and negatives appears as simply normal. The decline continues, falling below normal, passing through the savant level and then into low-functioning or dysfunctional.

From this spectrum perspective, there is less clarity when discussing separate categories for the cognitively disabled in need of assistive technology and the normal population. For HCI, this suggests that any gains from catering to differing cognitive styles may also be reaped by others not labeled with a particular cognitive style. This view is echoed in Alan Dix’s observations that assistive technologies for neurodiverse students have the effect of making the material more accessible to the wider student population [ 3]. Catering to outliers in a population reaps rewards further afield, not just for those with “impairments.” For HCI, this means that supporting differing cognitive styles should be something all software does rather than being limited to assistive ghettos. This also promises benefits, to a wider range of users, from research into neurodiversity interaction design.

The social model of disability.

The final pillar of neurodiversity
indicates that the general term
disability is applied not because of
an inability to function but rather
because of an innate inability
to operate by modern society’s
standards. The social model of
disability suggests that disability
is more a matter of an inability
to comply with social norms and
use society’s resources than a
fundamental lack of cognitive abil-
ity. For example, in a pre-literate
society, someone with dyslexia
would have no problem function-
ing and would not be considered
disabled. In a pre-urban society,
an individual with autism, toil-
ing long hours over the same
task in a field, may stand out less
and not be in need of “care.”
From this point of view, the
combination of society plus a
neurological condition makes a
difference a disadvantage, and so
a disability. Lev Vygotsky called
this idea disontogenesis: disability
compounded by society. As Vic
Finkelstein says, “The central issue
in our campaigns for a better life,
therefore, ought to be concerned
with issues around emancipation,
and this requires struggles for
social change rather than concen-
trating on individual experiences,
‘rehabilitation,’ etc.” [ 4].

Neurodiversity HCI
One of the objectives of neurodi-
versity HCI would be to expand
the broader social-justice aims
of the neurodiversity movement.
Neurodiversity is about rejecting
the idiom of impairment. It tries to
promote an understanding of alter-
native cognitive styles, their nega-
tive and positive sides. Significant
social discrimination and injustic-
es against the neurodiverse come
from inaccurate perceptions of
their limitations and abilities.