Lexical effects in left neglect dyslexia: A study in Italian patients.

This study investigated whether and to what extent the reading performance
of six Italian right brain-damaged patients with left neglect dyslexia was
affected by lexical variables. The lexicality of responses (either words
or nonwords) and the distribution of substitution vs. omission neglect
errors were measured. Patients were given the following tasks: (i) Reading
aloud monomorphemic words of different frequencies and nonwords with
different degrees of similarity to real words (Experiment 1); (ii) Reading
aloud morphologically complex (suffixed) derived words and morphologically
complex (suffixed) nonwords (Experiment 2). Patients could be
distinguished in terms of their sensitivity to the lexical status of the
target. Four patients exhibited lexicality effects in their reading
performance, while two patient did not. The dissociation is discussed in
terms of the interaction between defective visuo-spatial analysis, which
characterises neglect, and higher-order lexical knowledge. The suggestion
is made that lexical effects in neglect dyslexia reflect a relative
preservation of visuo-spatial processing of the left side of the letter
string, its absence a more severe neglect disorder. This interpretation of
the occurrence of lexical effects in left neglect dyslexia in terms of
severity of the spatial disorder is specific to the domain of reading,
however, and does not extend to other manifestations of unilateral spatial
neglect. Finally, the relationship between error type (omissions vs.
substitutions) and the absence vs. presence of lexical effects is
considered.