Abstract
Purpose: Many studies of reading and visual recognition of familiar figures have used Roman-alphabetic letters. While conclusions drawn from such studies have practical value, their theoretical application may be limited due to the uniform complexity of the stimulus set. Hieroglyphic script elements such as Chinese characters (CC) have a wide range of complexity and thus elicit more informative data. In this study a standard CC battery was built. Acuity and critical band noise masking were measured using CC and English Sloan letters (SL) and results were compared. Methods: The 500 most frequently used CC were divided into 6 groups by the number of strokes. From each group, 10 CC with uniform inter-character Euclidian distances were chosen. Acuity thresholds for the 60 CC and 10 SL were obtained from young, native Chinese readers who had at least 10 years of education in reading English. Recognition contrast thresholds for CC in the 2–4, 10–12, and 16–18 stroke groups as well as for SL were measured in band-passed white noise of various peak spatial frequencies and 1-octave bandwidth. Results: Acuity character size for CC increases linearly but slowly with stroke frequency (stroke/char). Mean acuity sizes for the 2–4 stroke and the 16–18 stroke groups are 4.4 and 6.5 arcmin. Acuity sizes for the 2–4 stroke group are similar to those for SL if the stroke width is matched (otherwise, are about 30% larger). Noise masking results suggest that critical bands for the 2–4 stroke group and SL are similar, but the peak spatial frequency of the critical band increases with increasing CC stroke frequency, and the bandwidth tends to broaden. Conclusions: Recognition of CC near acuity thresholds is only partially dependent on stroke frequency; other information such as the globe shape of characters may be utilized. While a single spatial frequency band may suffice for recognition of simple CC, multiple frequency bands are critical for the recognition of more complex CC.