This project investigates the gleam-glum effect, a well-replicated phonetic emotion association in which words with the [i] vowel-sound (as in “gleam”) are judged more emotionally positive than words with the [Ʌ] vowel-sound (as in “glum”). The effect is observed across different modalities and languages and is moderated by mouth movements relevant to word production. This research presents and tests an articulatory explanation for this association in three experiments. Experiment 1 supported the articulatory explanation by comparing recordings of 71 participants completing an emotional recall task and a word read-aloud task, showing that oral movements were more similar between positive emotional expressions and [i] articulation, and negative emotional expressions and [Ʌ] articulation. Experiment 2 partially supported the explanation with 98 YouTube recordings of natural speech. In Experiment 3, 149 participants judged emotions expressed by a speaker during [i] and [Ʌ] articulation. Contradicting the robust phonetic emotion association, participants judged more frequently that the speaker’s [Ʌ] articulatory movements were positive emotional expressions and [i] articulatory movements were negative emotional expressions. This is likely due to other visual emotional cues not related to oral movements and the order of word lists read by the speaker. Findings from the current project overall support an articulatory explanation for the gleam-glum effect, which has major implications for language and communication.

I recently established the gleam-glum effect confirming in both English and Mandarin that words with the /i/ vowel-sound (like “gleam”) are rated more emotionally positive than matched words with the /ʌ/ vowel-sound (like “glum”). Here I confirm that these vowel sounds also influence the semantic perception of monosyllabic pseudo-words. In Experiment 1, 100 participants rated 50 individual /i/ monosyllabic pseudo-words (like “zeech”) as significantly more positive than 50 matched /ʌ/ pseudo-words (like “zuch”), replicating my previous findings with real words. Experiment 2 assessed the gleam-glum effect on pseudo-words using a forced-choice task. Participants (n = 148) were presented with the 50 pairs of pseudo-words used in Experiment 1 and tasked to guess the most likely meaning of each pseudo-word by matching them with one of two meaning words that were either extremely positive or extremely negative in affective valence (Warriner et al., 2013). I found a remarkably robust effect in which every one of the 50 pseudo-word pairs was on average more likely to have the /i/ word matched with the positive meaning word and /ʌ/ word with the negative one (exact binomial test, p < .001, z = 7.94). The findings confirm that the gleam-glum effect facilitates bootstrapping meaning of words from their pronunciations. These findings coupled with previous real word findings (Yu et al., in press), showing not only that the effect encompasses the entire English lexicon but can also be explained with an embodied facial musculature mechanism, is consistent with the idea that sound symbolism may shape vocabulary use of a language over time by influencing semantic perception.