Neuropsychologia 45 (2007) 939–953
Exploring the dynamics of aphasic word production using
the picture–word interference task: A case study
Carolyn E. Wilshire
, Leonie M. Keall
, Elizabeth J. Stuart
, Debra J. O’Donnell
School of Psychology, Victoria University of Wellington, New Zealand
Department of Psychology, Monash University, Vic., Australia
Received 15 April 2006; received in revised form 28 July 2006; accepted 26 August 2006
Available online 4 December 2006
In this study, we use an auditory picture–word interference task to examine an anomic individual, NP. NP produced semantic errors in picture
naming, but his comprehension was relatively well preserved. In the task, pictures to be named were accompanied by semantically, phonologically
or unrelated distractors, presented at onsets ranging from −200 ms (before target) to +400 ms (after target). Naming latencies were measured. A
group of 12 older controls showed semantic interference (slower latencies with semantic than with unrelated distractors), which was signiﬁcant at
−200 ms, and steadily diminished across later onsets. In contrast, at 0 ms, NP showed powerful semantic facilitation. There were no signiﬁcant
semantic effects at other onsets, but the trends, particularly at later onsets, were towards interference. Phonological effects for NP were in the
same direction as for controls (facilitation) but were of greater magnitude. Indeed, NP showed a reliable facilitatory effect at 0 ms (and trends at
−200 ms and +200 ms), but a similar trend in controls failed to reach signiﬁcance. Within recent models of this task, in which semantic facilitation
effects are attributed to an early, pre-lexical semantic processing stage, NP’s pattern indicates that semantic processing is abnormally prolonged.
The phonological facilitation effects are also consistent with this interpretation. We discuss their implications and future applications of the task
© 2006 Elsevier Ltd. All rights reserved.
Keywords: Aphasia; Spoken word production; Picture–word interference task; Anomia
According to most current theories, word production involves
at least two major processes or stages—lexical selection and
phonological encoding (e.g., Caramazza, 1997; Dell, 1986,
1988; Levelt, 1989; Levelt, Roelofs, & Meyer, 1999; MacKay,
1987; Roelofs, 1992, 1997; Stemberger, 1985). During lexi-
cal selection, the speaker retrieves a representation of the word
that best matches the concept to be expressed, which is not yet
speciﬁed as to its form.
During phonological encoding, the
A portion of the data reported in this paper was presented at the 43rd Annual
Meeting of the Academy of Aphasia, Amsterdam, 2005.
Corresponding author at: School of Psychology, Victoria University of
Wellington, P.O. Box 600, Wellington, New Zealand. Tel.: +64 44 636 036;
fax: +64 44 635 402.
E-mail address: Carolyn.Wilshire@vuw.ac.nz (C.E. Wilshire).
Unless otherwise speciﬁed, the term “lexical representation” refers to that
representation accessed during spoken word production. For most of the ensuing
discussion, it is not necessary to specify whether this lexical representation is the
same one that is activated during auditory word recognition (and during reading
or written production), or whether it is unique to production. We address this
issue only where relevant to our particular theoretical account.
speaker then generates a complete phonological plan for the
word. Recent research has utilised this two-stage framework
to characterise word production impairments in aphasia (e.g.,
Badecker, Miozzo, & Zanuttini, 1995; Foygel & Dell, 2000;
Laine & Martin, 1996; Lambon Ralph, Sage, & Roberts, 2000;
Rapp & Goldrick, 2000; Wilshire & Saffran, 2005). Within
this framework, a word production disorder can be attributed
to any one of three primary types of impairment. The ﬁrst
is a general impairment activating semantic representations,
which will lead to errors in both production and comprehension,
particularly semantic errors (e.g., Howard & Orchard-Lisle,
1984; Rapp & Goldrick, 2000 (patient KE)). The second is an
impairment involving the lexical selection stage of word pro-
duction, which will lead to semantic and other whole-word
errors in production, but should not affect word comprehen-
sion (e.g., Lambon Ralph et al., 2000; Rapp & Goldrick, 2000
(patient PW)). The third is a phonological encoding impairment,
which will lead to the production of phonological errors (e.g.,
Rapp & Goldrick, 2000 (patient CSS); Wilshire & Nespoulous,
0028-3932/$ – see front matter © 2006 Elsevier Ltd. All rights reserved.