Abstract
Artificial “pseudo-fonts” have found widespread application in vision, cognitive neuroscience and reading research. Pseudo-fonts are designed to resemble the characters (glyphs) of an existing alphabet in terms of a set of common low-level features. A promising metric for matching the low-level features of a pseudo-font to the target alphabetic font is their perimetric complexity (PC). PC in the font context is defined as the sum of the inside and outside perimeters of the glyph, squared, divided by the glyph area, divided by 4pi (Pelli et al., Vis Res, 2006, Watson, Mathematica Journal, 2012). Previous research has found that PC predicts letter recognition accuracy in noise over a diverse range of fonts (Pelli et al., Vis Res, 2006). To link the use of pseudo-fonts to the visual acuity literature, we based our pseudo-font on the design principles developed by Louise Sloan in the 1950’s. Importantly, the Sloan font has been specified for eye chart optotypes by the US National Academy of Sciences, National Research Council on Vision (Adv. Ophthalmol, 1980). We created several hundred candidate glyphs that varied in their PC and ink-area using the Sloan 5X5 font grid. From this larger set, we selected two sets of glyphs that closely matched the letters of the upper-case roman alphabet on PC and area. The PseudoSloan TrueType and OpenType fonts are fully scalable and compatible with any operating system and software that supports these font types. Landolt C, tumbling E optotypes and the 26 roman letters are also included. The PseudoSloan font is available at https://osf.io/qhj2b/?view_only=f919f853cb6b426ebd7daff683cf34c2.