Neither Deep nor Shallow: A Classroom Experiment Testing the Orthographic Depth of Tone Marking in Kabiye (Togo)

The experiment reported here tests the Lexical Orthography Hypothesis, that is, the notion that the output of the lexical phonology is the most promising phonological depth for an exhaustive representation of tone by means of diacritics in the orthography of atone language. We conducted a controlled classroom experiment with 97 secondary school pupils learning written Kabiye, a Gur language of northern Togo. After testing their baseline skills in writing the standard orthography, the pupils participated in an eleven-hour transition course spread over three weeks in four parallel groups: DEEP (an experimental orthography representing the input of the lexical phonology), LEXICAL (representing the output of the lexical phonology), PHONEMIC (representing a level between the output of the lexical phonology and the output of the post-lexical phonology), and a control group. On the final day of the experiment, we tested their acquired skills in a dictation exercise. The results show that the LEXICAL group outperforms the other groups in three of the error types associated with adding diacritics, although they performed less well on the error type associated with writing long vowels. This initial evidence supporting the Lexical Orthography Hypothesis needs confirmation with reading and writing experiments on a variety of other tone languages.