The benefits occur because information is integrated across letters in words (e.g., Massaro & Sanocki, 1993 McClelland & Rumelhart, 1981), making the perceptual system more robust to limitations of letter-level processing (e.g., Oden, Rueckl & Sanocki 1991). However, higher level units in language impart strong benefits on the processing of their constituents in particular, word unitization in the brain strongly benefits letter processing. We begin, however, by commenting on how letter stimuli should be presented to maximize experimental sensitivity to visual processing.īecause words are highly meaningful units in reading, it is natural to use them to study reading. Letter research can benefit from discussion of the perceptual problems (Marr, 1982) that must be solved in letter processing during reading. The ability to exploit commonalities is a hallmark of expertise with letters nonexperts (i.e., those unfamiliar with the writing system) do not exploit regularities (Gauthier et al., 2006). These commonalities are constraints that create a family of objects for identification. These regularity effects imply that shared properties within a font (commonalities) are important in letter processing, in addition to distinctiveness. As a result, letter identification efficiency is reduced relative to same-font conditions. However, spatial and other properties are not as regular in a mixed font, and the perceptual system cannot exploit them as well.

Note that mixing fonts increases the distinctiveness of individual letters, because differences between fonts correspond with letter identities. In contrast, in mixed font conditions, although there are often the same n alternative forms and letter identities, they are from two or more fonts, instead of a single font. The interpretation of these results is that letter processing becomes more efficient because the perceptual-processing system tunes itself to exploit regularities of a font (see also Sanocki, 1991b, 1992 Walker, 2008). The psychological evidence that commonalities contribute to efficiency comes from advantages found in identification of letters of consistent, regular fonts, relative to mixed or irregular fonts (Gauthier, Wong, Hayward, & Cheung, 2006 Sanocki, 1987, 1988, 1991b, 1991c). The proportions vary somewhat among fonts, but within a restricted range, making fonts of the same point size appear larger or smaller (Luna, 1992). This frame system constrains size proportions within the font Footnote 3 for example, the ratio of x-height to cap height and the length of ascenders and descenders are characteristics of a particular font (Baines & Haslam, 2005). In type design, letters of the same font use a systematic reference frame of ascender line, x-height, baseline, and descender line, illustrated in Fig. To anticipate, we conclude that the commonalities that have been supported most strongly are spatial parameters concerning the size of letter parts and their interrelations. This research will be reviewed, and the importance of specific commonalities will be discussed. The idea that commonalities are important in letter perception receives validation from a small body of psychological studies in which commonalities increase the efficiency of human letter identification.

Letter fonts