Diagram of the DRC ModelThe DRC model is a computational model of reading which is intended to explain how skilled readers perform certain basic reading tasks. The acronym emphasizes the two fundamental properties of the model: it is a Dual Route model, and within the model information processing occurs in a Cascaded fashion.

The model consists of three routes, the lexical semantic route, the lexical nonsemantic route, and the GPC route. Each route is composed of a number of interacting layers. These layers contain sets of units. The units represent the smallest individual symbolic parts of the model, such as words in the orthographic lexicon or letters in the letter unit layer.

There are two ways in which the units of different layers interact. One is through inhibition, where the activation of a unit makes it more difficult for the activation of other units to rise. The other is through excitation, where the activation of a unit contributes to the activation of other units. Units may also interact on the same level through lateral inhibition.

The 2001 Psychological Review paper on DRC (9.1MB PDF) by Coltheart et al. describes version 1.0 of the model in detail.


A simulator of the lexical nonsemantic and GPC routes is available for Mac OS X, Linux (x86) and Windows. It is a command line application, so it must be operated from the Terminal application in Mac OS X, the Shell in Linux or the Command (or DOS) Prompt in Windows. If you are not familiar with the use of this kind of software, there are many excellent tutorials available via Google search.

To get started download the latest build and use the following command line to see a list of options the simulator supports:

drc --help

A straightforward simulation of reading aloud a word can be achieved with the command:

drc word


Simulator users may find the following documents useful:

Understanding DRC’s Output
Working With DRC’s Parameters
Writing DRC Batch Files


Some other resources related to DRC and reading:

Max Coltheart’s Website
University of Ottawa – Omnilex Database

The ARC Nonword Database

Related Papers

Coltheart, M. and Rastle, K. (1994). Serial Processing in Reading Aloud: Evidence for Dual-Route Models of Reading. Journal of Experimental Psychology: Human Perception and Performance, 20, 1197-1211.

Coltheart, M. and Leahy, J. (1996). Assessment of lexical and nonlexical reading abilities in children: Some normative data. Australian Journal of Psychology, 48, 136-140.

Coltheart, M., Langdon, R. and Haller, M. (1996). Computational cognitive neuropsychology. In Dodd B, Worrall L and Campbell R (eds). Evaluating Theories of Language: Evidence from Disordered Communication. London: Whurr Publishers.

Rastle, K and Coltheart, M. (1998). Whammies and double whammies: The effect of length on nonword reading. Psychonomic Bulletin & Review, 5, 277-282.

Cestnick, L. and Coltheart, M. (1999). The relationship between language-processing and visual-processing deficits in developmental dyslexia. Cognition, 71, 231-255.

Coltheart, M., Woollams, A., Kinoshita, S. and Perry, C. (1999). A position-sensitive Stroop effect: Further evidence for a left-to-right component in print-to-speech. Psychonomic Bulletin & Review, 6, 456-463.

Rastle, K. and Coltheart, M. (1999). Serial and strategic effects in reading aloud. Journal of Experimental Psychology: Human Perception & Performance, 25, 482-503.

Rastle, K. and Coltheart, M. (1999). Lexical and nonlexical phonological priming in reading aloud. Journal of Experimental Psychology: Human Perception & Performance, 25, 461-481.

Rastle, K. and Coltheart, M. (2000). Serial processing in reading aloud: Reply to Zorzi (2000). Journal of Experimental Psychology: Human Perception & Performance, 26, 1232-1235.

Rastle, K. and Coltheart, M. (2000). Lexical and nonlexical print-to-sound translation of disyllabic words and nonwords. Journal of Memory & Language, 42, 342-364.

Rastle, K., Harrington, J.M., Coltheart, M. and Palethorpe, S. (2000). Reading aloud begins when the computation of phonology is complete. Journal of Experimental Psychology: Human Perception & Performance, 26, 1178-1191.

Coltheart, M., Rastle, K., Perry, C., Langdon, R. & Ziegler, J. (2001). DRC: A Dual Route Cascaded model of visual word recognition and reading aloud. Psychological Review, 108, 204-256.

Roberts, M., Rastle, K., Coltheart, M. & Besner, D. (2003). When parallel processing in visual word recognition is not enough: New evidence from naming. Psychonomic Bulletin & Review, 12, 405-414.

Coltheart, M. (2004). Are there lexicons? Quarterly Journal of Experimental Psychology, 57A, 1153-1171.

Blazely, A., Coltheart, M., & Casey, B. (2005). Semantic dementia with and without surface dyslexia. Cognitive Neuropsychology, 22, 695-717.

Coltheart, M. (2005). Analysing developmental disorders of reading. Advances in Speech-Language Pathology, 7, 49-57.

Coltheart, M. (2005). Modelling reading: The dual-route approach. For Snowling, M.J. & Hulme, C. (Eds). The Science of Reading. Oxford: Blackwells Publishing.

Bates, T.C., Castles, A., Luciano, M., Wright, M.J., Coltheart, M. & Martin, N.G. (2006). Genetic and environmental bases of reading & spelling: A unified genetic dual route model. Reading and Writing, 20, 147-171.

Castles, A., Bates, T. & Coltheart, M. (2006). John Marshall and the developmental dyslexias. Aphasiology, 20, 871-892.

Castles, A., Bates, T., Coltheart, M., Luciano, M. & Martin, N.G. (2006). Cognitive modelling and the behavior genetics of reading. Journal of Research in Reading, 29, 92-103.

Coltheart, M. (2006). Acquired dyslexias and the computational modelling of reading. Cognitive Neuropsychology, 23, 96-109.

Coltheart, M. (2006). Dual route and connectionist models of reading: An overview. London Review of Education, 4, 5-17.

Howard, D., Nickels, L., Coltheart, M. & Cole-Virtue, J. (2006). Cumulative semantic inhibition in picture naming: experimental and computational studies. Cognition, 100, 464-482.

Rastle, K., & Coltheart, M. (2006). Is there serial processing in the reading system; and are there local representations? In Andrews, S. (Ed). All about words: Current issues in lexical processing. Hove: Psychology Press.

Coltheart, M., Tree, J., & Saunders, S. (2008). Computational modelling of reading impairments in semantic dementia [Abstract]. Australian Journal of Psychology, 60(1), 64.

Mousikou, P., Coltheart, M. & Saunders, S. (2008). What is the nature of the masked onset priming effect: phonological, graphemic or both? Evidence from behavioural and computational data [Abstract]. Australian Journal of Psychology, 60(Suppl. 1), 88.

Nickels, L., Biedermann, B., Coltheart, M., Saunders, S. & Tree, J. (2008). Computational modeling of phonological dyslexia: How does the DRC model fare? [Special Issue]. Cognitive Neuropsychology, 25(2), 165-193.

Rastle, K., Havelka, J., Wydell, T.N., Coltheart, M. & Besner, D. (2009). The cross-script length effect: Further evidence challenging PDP models of reading aloud. Journal of Experimental Psychology: Learning, Memory and Cognition, 35, 238-246.

Mousikou, P., Coltheart, M., Saunders, S., & Yen, L. (2010). Is the orthographic/phonological onset a single unit in reading aloud? Journal of Experimental Psychology: Human Perception & Performance, 36(1), 175-194.

Mousikou, B., Coltheart, M., & Saunders, S. (2010). Computational modelling of the masked onset priming effect in reading aloud [Special Issue]. European Journal of Cognitive Psychology, 22(5), 725-763.

Mousikou, P., Coltheart, M., Finkbeiner, M. & Saunders, S. (2010). Can the dual-route cascaded computational model of reading offer a valid account of the masked onset priming effect? The Quarterly Journal of Experimental Psychology, 63(5), 984-1003.

Biedermann, B., Nickels, L., & Coltheart, M. (in press). Effects of homophony on reading aloud: Implications for models of speech production. Language and Cognitive Processes.

Coltheart, M., Tree, J. & Saunders, S. (in press). Computational modelling of reading in semantic dementia: Comment on Woollams, Lambon Ralph, Plaut and Patterson (2007). Psychological Review.


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