中華心理學刊 民 90，43 卷，2 期，155-173
Chinese Journal of Psychology 2001, Vol.43, No.2, 155-173

I-Ping Chen（Center for General Education and Institute of Neuroscience, National Yang-Ming University）；Su-Ling Yeh（Department of Psychology, National Taiwan University）；Sanyuan Lin（Department of Psychology, National Taiwan University）

Abstract

It has been shown that in identifying letters, Fourier components within a certain range of spatial frequencies are better utilized by the visual system than others (e.g. Solomon & Pelli, 1994). However, it is not clear whether it is the phase or the amplitude/power information within this critical band that mediates letter identification. We used a partial phase-randomization paradigm to determine the critical phase band for Chinese character recognition. The results indicated that for Chinese character recognition, there is indeed a critical spatial frequency range (with a peak of 8 cycles/image and a bandwidth of about two octaves) whose phase information is more important than that of other bands. The critical phase band was not an artifact caused either by the critical quantity of phase information required for identifying characters or by the shape of characters' power density functions. The contrast between the performances of ideal and human observers was evaluated to verify the psychological reality of the critical phase band. When comparing our results with previous critical band studies, we found that the critical phase bands for letter and character recognition were virtually identical (peaking at 8-10 cycles/image, with a bandwidth of about 2 octaves), while the critical power band for a given recognition task was image-statistics-dependent. It thus appears that there is a functional dissociation between the critical phase and power bands. The implication of our results in relation to a recent model for the phonological receding process of Chinese character recognition (Chua, 1999) is also discussed.

Keywords：Chinese character, Critical band、Spatial frequency, Phase、Ideal observer, Phonological recoding