This study applies mathematical linguistics to explore the morphological richness and syntactic freedom of Japanese advertising slogans and identify associations between the morphosyntactic features and the popularity of slogans. The data were drawn from the Tokyo Copywriters Yearbook, which includes 12 genres of advertising slogans. Mean dependency distance (MDD) and entropy (ENTR) were employed to measure syntactic diversity, and moving-average morphological richness (MAMR), moving-average mean size of paradigm (MAMSP), and mean word length (MWL) to measure lexical diversity. The findings indicate that in terms of syntactic complexity, slogans of the imperative form were the simplest and slogans of the volitional form were the most complex. In information amount, exclamatory slogans had the highest and volitional slogans the lowest. Spearman’s rank correlation test for MMR, MAMSP, MWL, MDD, and ENTR showed that MAMR and MDD reflect the proposed ‘complexity trade-off hypotheses’. Furthermore, the analysis of the Tokyo Copywriters Club (TCC)-Prize-winning slogans from 2018 to 2021 reveals a tendency towards popularity among the Japanese in the past four years, such that the simpler the slogans, the better. We hope that this research will aid copywriters in producing effective advertising slogans.
Keywords: Japanese, advertising slogan, lexical diversity, morphological richness, syntactic complexity
