An upper- and lowercase alphabetic similarity matrix, with derived generation similarity values

Abstract

A full upper-and lowercase visual similarity matrix is presented for a standard set of computer characters, implemented on the Apple-Psych system. The 2,704 (52 x 52) letter pairs were rated by 12 subjects each. From the ratings, generation and veridical similarity values are derived, and they are tabled for use in research on mixed-case letter matching. In addition, the results of multidimensional scaling and cluster analyses are presented, which give complementary, simplified descriptions of the data. The impact of visual similarity on pure-ease letter comparisons (e.g., between "A" and "A") is well documented. Letters that are commonly confused with one another (e.g., "GQ") produce longer reaction times (RTs) in same-different matching tasks than do letters that are rarely confused (Bagnara, Boles, Simion, & Umilta, 1983). This effect is a source of evidence that pure-case letter pairs are matched physically (visually), and, indeed, the task of matching such pairs is known as the physical matching task (Posner, 1978). Mixed-ease letter comparisons (e.g., between "A" and "a") have come to be known as name matches, because introspection and early experimental results suggested that such matches are made by extracting and comparing phonetic representations of the letter names (Dainoff &

Interactive Visual and Postvisual Processes and Their Roles in Form-Specific Memory.

“…Ninety-six English words were chosen from Webster's Vest Pocket Dictionary (1989) with the constraints that the three-letter beginnings (i.e., stems) of each word (a) were exclusive with respect to other words used in the experiment, (b) contained only letters with dissimilar uppercase and lowercase structures (A/a, B/b, D/d, E/e, F/f, G/g, H/h, L/l, M/m, N/n, R/r, T/t) according to analyses in Boles and Clifford (1989), and (c) could be completed to form at least 10 common words found in the dictionary. These were labeled "critical words."…”

Second-order mappings in grapheme–color synesthesia

“…Letter name similarity Number of shared phonemes in two letter names (e.g., "bee" and "dee" have 1 shared phoneme, /i/) Discrimination RT Reaction time on a same-different discrimination task for uppercase letter pairs (Podgorny & Garner, 1979) Ratings A (similarity) Similarity ratings of uppercase letters (Boles & Clifford, 1989) B (similarity) Similarity ratings of lowercase letters (Boles & Clifford, 1989…”

“…The remaining measures were previously published behavioral data on letter similarity, and thus may have been influenced by letter shape, frequency, order of acquisition, and (potentially) many other factors. These measures include discrimination RTs, from a same-different task in which the subjects were briefly presented with letter pairs (Podgorny & Garner, 1979); comparison ratings of letter similarity or difference (Boles & Clifford, 1989;Podgorny & Garner, 1979); and confusion, from letter-naming tasks using degraded stimuli (Gilmore, Hersh, Caramazza, & Griffin, 1979;Gupta, Geyer, & Maalouf, 1983).…”

Varieties of Pure Alexia: The Case of Failure to Access Graphemic Representations

“…The size of lowercase letters was norm alised to the size of upper-case stim uli. Only letters judged to hav e differen t shap e in upper and lo wer case (Boles & Clifford , 1989) were used in tasks where letters were sho wn in differen t form ats. Specifically , we selected the follo wing pairs of letters: A-a, B-b, D-d, E-e, F-f, G-g, H-h, N-n, P-p, Q-q, R-r and T-t. …”