| |
Abstract:
The convention for characterizing the reading deficit
displayed by patients with pure alexia (also referred to as
letter-by-letter readers) is to plot their naming latency as a
function of string length. This, however, does not fully illustrate
the extent of their residual reading abilities since many patients
demonstrate varying levels of unconscious, covert word processing.
One possible view is that deficit severity, as characterized by
naming difficulty shown in increased reaction times in naming
latency, should predict the extent of residual covert processing.
To examine this relationship, two letter-by-letter readers, EL and
DK, were administered naming latency tasks and also several tasks
which measure residual covert word processing. Both patients showed
similar naming latency performance yet varied significantly on
tasks which measured covert word processing. EL was able to make
binary semantic classifications and lexical decisions of briefly
presented letter strings at a rate significantly higher than
chance. EL also showed word interference in incongruent conditions
in two Stroop-like tasks. One task required determining the ink
color of words and the other, the spatial position of words. DK,
however, failed to show covert word processing as measured by any
of these tasks. The results suggest that naming latency does not
predict covert word processing abilities and that both factors
should be considered when describing the reading pattern of these
patients.
|
