Does tonal information affect the early stages of visual-word processing in Thai?

Abstract

Thai offers a unique opportunity to investigate the role of lexical tone processing during visual-word recognition, as tone is explicitly expressed in its script. In order to investigate the contribution of tone at the orthographic/phonological level during the early stages of word processing in Thai, we conducted a masked priming experiment—using both lexical decision and word naming tasks. For a given target word (e.g., ห้อง/hᴐ:ŋ2/, room), five priming conditions were created: (a) identity (e.g., ห้อง/hᴐ:ŋ2/), (b) same initial consonant, but with a different tone marker (e.g., ห่อง/hᴐ:ŋ1/), (c) different initial consonant, but with the same tone marker (e.g., ศ้อง/sᴐ:ŋ2/), (d) orthographic control (different initial consonant, different tone marker; e.g., ศ่อง/sᴐ:ŋ1/), and (e) same tone homophony, but with a different initial consonant and different tone marker (e.g., ธ่อง/t^hᴐ:ŋ2/). Results of the critical comparisons revealed that segmental information (i.e., consonantal information) appears to be more important than tone information (i.e., tone marker) in the early stages of visual-word processing in alphabetic, tonal languages like Thai. Thus, these findings may help constrain models of visual-word recognition and reading in tonal languages.

Keywords:

• Lexical decision
• Masked priming
• Rapid naming
• Thai
• Tone processing
• Visual-word processing

This research has been supported in part by Grant PSI2011-26924 from the Spanish Government. We would like to thank Sudaporn Luksaneeyanawin, Wirote Aroonmanakun, and Theeraporn Ratitamkul, Centre for Research in Speech and Language Processing (CRSLP) and the Linguistics Department, Chulalongkorn University, Bangkok for advice and assistance as well as use of the laboratory facilities. Also thanks to Chalong Saengsirivijam for assistance with participant recruitment.

Notes

¹ Tones are marked in the Thai examples cited in this paper as follows: 0 = mid, 1 = low, 2 = falling, 3 = high, 4 = rising. This is based on the system that was developed at the Linguistics Research Unit (LRU) of Chulalongkorn University (Luksaneeyanawin, 1993). International Phonetic Alphabet (IPA) transcription is used for the transcription of all other Thai text.

² As an anonymous reviewer indicated, one might argue that the obtained priming effects may reflect a form-priming effect on the basis of prime/target orthographic similarity [i.e., ห้อง (C+ T+) < ห่อง (C+ T–) < ศ้อง (C– T+) = ธ่อง (C– T–+) = ศ่อง (C– T–); ห้อง would be the target word] rather than a phonological effect. This interpretation would also support the main conclusion of the present experiment—namely, that segmental information plays a larger role than tonal information in the early stages of visual-word recognition.