The development of abstract letter representations for reading: Evidence for the role of context

Abstract

We review evidence that in the course of reading, the visual system computes abstract letter identities (ALIs): a representation of letters that encodes their identity but that abstracts away from their visual appearance. How could the visual system learn such a seemingly nonvisual representation? We propose that different forms of the same letter tend to appear in similar distributions of contexts (in the same words written in different ways) and that this environmental correlation interacts with correlation-based learning mechanisms in the brain to lead to the formation of ALIs. We review a neural network model that demonstrates the feasibility of this common contexts hypothesis and present two experiments confirming some novel predictions: (a) repeatedly presenting arbitrary visual stimuli in common contexts leads those stimuli to be confusable with each other, and (b) different forms of the same letter are more confusable with each other in word-like contexts than in nonword-like contexts. We then extend the model to use real pictures of letters as input and simulate some of the novel empirical findings from the experiments.

Do young readers have fast access to abstract lexical representations? Evidence from masked priming

“…Further experimentation is necessary to examine in detail the time course of the processing of visual versus abstract representations in developing readers (e.g., registering participants' ERP (event-related potential) waves, monitoring participants' eye movements during reading, examining RT distributions) and, as suggested by a reviewer, how this pattern could be modulated by the level of reading ability across developing readers (with the expectation that the difference between the SIM and DIS effects would be greater for the less advanced readers). Another aspect that requires further research is to explicitly test the idea that visually similar letters may provide the context to create abstract representations, as suggested by Polk et al (2009). Finally, the current findings also provide a cautionary note regarding the interpretation of masked priming effects with younger readers.…”

“…Note, however, that Jackson and Coltheart (2001) acknowledged that these abstract representations might not be as efficiently accessed for developmental readers. An alternative view was proposed by Polk et al (2009). They proposed that letters that have cross-case visual similarity (e.g., c/C) would form a context for the letters that have cross-case visual dissimilarity (e.g., r/R).…”

Auditory evoked potential: a proposal for further evaluation in children with learning disabilities

“…Scientific research has focused on the understanding of the processes involved in general learning ( Bledowski et al, 2009 ; Möhler, 2009 ; Nippold and Sun, 2009 ; Op de Beeck and Baker, 2009 ; Polk et al, 2009 ; Yadon et al, 2009 ) and pathological brain processes involved in learning disorders. The major investments in the area are related to dyslexia highlighting electrophysiological studies ( Chermak and Musiek, 1994 ; Arehole et al, 1995 ; Purdy et al, 2002 ; Horowitz-Kraus and Breznitz, 2008 ; Sebastian and Yasin, 2008 ; Andreadis et al, 2009 ; Hämäläinen et al, 2013 ).…”

Lexical enhancement during prime–target integration: ERP evidence from matched-case identity priming

“…This poses some problems for accounts that assume that an abstract orthographic code is automatically attained during word processing in the absence of lexical feedback, and favors fully interactive models of visual-word recognition. Further research should be devoted to exploring how these abstract representations are constructed (and retrieved) in the process of learning to read (see Polk et al, 2009 6 As two reviewers pointed out, one might argue that the case-change effect observed with pseudowords might be driven by a verification mechanism used mostly with pseudoword stimuli in lexical decision, which somehow could be more sensitive to case changes. That would save feedforward accounts of sublexical orthographic processing that hypothesize a shift from case-specific to case-invariant letter representations.…”