The ability to understand and produce language is unique to humans, but at the same
time, language processing is influenced by additional cognitive processes that other
species share. Language may be described as a set of linguistic representations and
rules, but it is other cognitive abilities, such as attention and short-term memory,
that enable us to access and use those representations in verbal communication. In
this role, these “other” cognitive processes are termed “language control” processes.
Further, a substantial amount of research links language impairments to impairments
of these “control” processes. This view of language abilities and language impairments
has important implications for the rehabilitation of language disorders. It assumes
that language impairment in aphasia reflects impaired access to linguistic representations
rather than loss of language knowledge. Such a perspective allows consideration of
treatment hypotheses that emphasize both language content (e.g., semantic or phonological
variables) and access to that content (e.g., using priming techniques or focusing
on short-term memory for language). Furthermore, this view is in keeping with recent
research on factors that will maximize effectiveness of treatment, including style
of training (e.g., errorless versus errorful learning[1]) and intensity and duration of treatment.[2]
The articles in this issue of Seminars in Speech and Language focus on the role of nonlinguistic cognitive processes in language processing with
discussions of the implications of these control processes for our understanding of
language impairment and its remediation. The articles were first presented at the
Second Annual Eleanor M. Saffran Cognitive Neuroscience Conference at Temple University
in Philadelphia, Pennsylvania, in September 2007. This conference was established
in honor of Eleanor M. Saffran, a pioneer in neuropsychology and aphasia research.
The annual meeting serves as a forum for the interdisciplinary discussion of topics
in cognitive neuroscience. It is open to clinical practitioners, scientists, faculty,
and students representing the many disciplines that connect in some way with questions
concerning cognitive and neural processing.
The first article, by William Hula and Malcolm McNeil, discusses approaches to the
study of attention in aphasia and provides evidence for impaired attentional processes
in aphasia. The second, by Bruce Crosson, reports a therapy approach that uses intentional
processes that enable initiation of action to shift lateralization of word production
to the right hemisphere and facilitate word retrieval. The third, by Randi Martin
and Corinne Allen, describes executive processes (especially inhibition) and how these
are involved in language processing and aphasia. Prahlad Gupta's article provides
a tutorial on a relatively new area of investigation, the role of computational models
in studying language behaviors and aphasia. He emphasizes that computational models
can extend behavioral investigations of language and other cognitive processes but
cannot replace them. The next article, by Anjan Chatterjee, reviews the neural underpinnings
of “spatial semantics,” the interface of spatial thought and language, and discusses
the importance of considering both spatial and object semantics when evaluating language
impairment. The final article, by Gerry Stefanatos, discusses the role of temporal
processing in impairments of speech perception and factors to consider in the diagnosis
of word deafness and Wernicke's aphasia.
Together, these six articles provide a comprehensive introduction to the study of
the interaction of language with other cognitive processes. They should provide the
reader with a sampling of the many interesting phenomena involved in language processing
and the relevance of these phenomena to our understanding and treatment of language
disorders.
