Domain specificity in orthographic long-term and working memory
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1
Johns Hopkins University, Department of Cognitive Science, United States
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2
Rice University, Department of Psychology, United States
Introduction.
It is commonly assumed that skills with a long evolutionary history, such as spoken language, object recognition, attention, and navigation are supported by neural networks shaped by evolution and grounded in the genetic blueprint. In contrast, orthographic processing (reading and spelling) are evolutionarily recent human inventions and, therefore, are not supported by neural networks specifically designed for these skills. This raises various questions regarding how the neural substrates of orthographic processing are related to those of evolutionarily older skills. One hypothesis is that reading and spelling are supported by networks that carry out related functions in other evolutionarily older domains. An alternative is that domain-specific orthographic processing networks have developed over the course of learning to read and spell (Dehaene, 2009). In this study, we examine the domain specificity of orthographic processing networks through a detailed evaluation of the individuals with deficits affecting either orthographic long-term or working memory (O-LTM and O-WM). We specifically evaluate their performance in other long-term and working memory domains, including: phonological, visual and semantic.
Methods and Results.
Four individuals with acquired dysgraphia exhibited spelling accuracy significantly below that of neurotypical controls (Table 1, PALPA 40). In addition, they demonstrated deficits affecting either orthographic working memory (DTE, PQS) or orthographic long-term memory (DSN, JGL), as determined by a significant effect on spelling performance of word frequency but not length for the latter and the reverse pattern for the former (Table 1).
To evaluate the modality specificity of the O-WM memory deficits, working memory was evaluated in the following domains: visual spatial (Corsi Blocks, Fractal WM), semantic (Semantic Category Probe) and phonological (Nonword Probe, Digit Span Matching). The accuracy and spans of both individuals with O-WM deficits on each of these tasks were not different from that of neurotypical, age-matched controls.
To evaluate the modality specificity of the O-LTM deficits, processing in visuo-spatial domains that rely on ventral temporal cortex was evaluated: Face Processing (seven tasks, including recognition of famous faces, silhouettes, and old/new face memory), visual object processing (BORB subtests 2, 7 and a 10, measuring low level visual processing and object decision) and semantic processing (PPVT and Pyramids and Palm Trees 3 picture version). For both individuals with O-LTM deficits, performance on each of these tasks was not different from that of neurotypical age-matched controls.
Discussion.
Individuals with acquired dysgraphia demonstrated deficits that selectively affected orthographic long-term or working memory, sparing related domains of visual, phonological and semantic long-term or working memory. The findings provide strong evidence for the domain specificity of core orthographic (spelling) processes and representations, supporting the hypothesis that highly-practiced evolutionarily recent skills may be instantiated in independent neural substrates. Additionally, the finding of the modality-specificity of O-WM is relevant to questions regarding the independence of working memory and long-term memory. Embedded process accounts (Cowan, 1999) posit that working memory refers to the portion of long-term memory that is in the focus of general attentional processes. Evidence of modality-specific working memory deficits represents a challenge to this framework.
Acknowledgements
The work is part of a multi-site, NIDCD-supported project examining language recovery neurobiology in
aphasia (DC006740). We thank Dr. Tirta Susilo for face processing experiments and normative data.
References
Cowan, N. (1999). An embedded-processes model of working memory. In: Models of working memory: Mechanisms of active maintenance and executive control, eds. A. Miyake & P. Shah. Cambridge University Press.
Dehaene, S. (2009). Reading in the Brain. New York: Viking.
Keywords:
orthographic processing,
orthographic long term memory,
orthographic working memory,
spelling,
dysgraphia
Conference:
54th Annual Academy of Aphasia Meeting, Llandudno, United Kingdom, 16 Oct - 18 Oct, 2016.
Presentation Type:
Platform Sessions
Topic:
Academy of Aphasia
Citation:
Rapp
B,
Shea
J,
Mis
R and
Martin
R
(2016). Domain specificity in orthographic long-term and working memory.
Front. Psychol.
Conference Abstract:
54th Annual Academy of Aphasia Meeting.
doi: 10.3389/conf.fpsyg.2016.68.00095
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Received:
29 Apr 2016;
Published Online:
15 Aug 2016.
*
Correspondence:
Dr. Brenda Rapp, Johns Hopkins University, Department of Cognitive Science, Baltimore, MD, United States, rapp@cogsci.jhu.edu