Orthographic Processing and Reading
1.Reading words:From inkmarks to ideasWords are the building blocks of reading in written languages that use word spaces, and in those languages that use an alphabetic script, letters are the building blocks of words. When reading, the eyes fixate the majority of words in the text, and typically only once. This implies that readers are getting a foveal glimpse (for about a quarter of a second) of most words in the text and that the essence of skilled reading behavior is contained in the processing that is performed during that glimpse. Therefore, quite understandably, explaining how literate adults read single words has been one of the major goals of experimental psychology since the very inception of this science (Huey, 1908).The process of silent word reading (reading for meaning) minimally requires two types of codes: orthography (knowledge about letter identities and letter positions) and semantics (knowledge about the meanings of words) The process of reading aloud minimally requires an orthographic code and a phonological (knowledge about the sounds of words) code in order to generate a pronunciation. Although no more than two codes are necessarily required for each task, it has become increasingly clear that all three codes (orthography, semantics, and phonology) are involved in both silent reading and reading aloud. This has led to the development of a generic architecture for word recognition that emphasizes the key role for cross code interactions (e.g. Grainger Ziegler, 2008; Siedenberg McClelland, 1989) Much research on single word reading to date has therefore focused on the processing of semantic, phonological, and morphological (knowledge of word parts that carry meaning like prefixes and suffixes) information, while largely ignoring orthographic processing. This research bias was also exaggerated by an undue focus on the process of reading aloud as opposed to silent reading for meaning. The last decade, however, has been to witness to a surge in interest for basic orthographic processing during reading; the present article aims to summarize some key findings from this recent research.The importance of understanding orthographic processing for understanding reading in general can be best appreciated when considering the written word as both a visual object and a linguistic entity. From this perspective, single word reading is a combination of visual object identification processes and linguistic processing, with orthographic processing acting as the key interface between the two. Orthographic processing allows generic visual processing mechanisms to make contact with the linguistic processing that is specific to word stimuli compared with other kinds of visual object. This contact is established via three types of mapping: 1) letters to phonology to meaning; 2) letters to morphology to meaning; 3) letters to words to meaning (see Figure 7).2. Letter based word recognitionThere is a general consensus today among reading researchers that for languages that use an alphabetic script, visual word recognition is letterbased (see Grainger, 2008, for a summary of the arguments).2 That is, visual feature information is used to obtain information about the word's component letters, and a word's identity is mainly derived from information about letter identities and letter positions as opposed to word shape information that might be gained, for example, from ascending and descending letters in lowercase text. There is one key computational argument against a major role for holistic word shape information in reading: it is more efficient to solve shape invariance at the level of individual letters (N=26) than at the level of whole words (N~30,000) Shape invariance refers to our ability to recognize words (and other kinds of visual objects) independently of the precise visual format in which they are presented (e.g. lowercase vs. UPPERCASE; courier font vs.