Reversed sound symbolism in speech sound disorders: Evidence for atypical cross-modal integration in a transparent...

This study examined sound-shape matching performance (the bouba-kiki effect) in Turkish-speaking children with speech sound disorders (SSD) and their typically developing (TD) peers. Participants included 60 children aged 51-71 months: 30 with SSD and 30 typically developing (TD) peers, all of whom demonstrated normative language abilities as confirmed by standardized assessments. Language and speech skills were assessed using the Turkish Early Language Development Test (TEDİL) and the Articulation and Phonology Test (SET). Sound-shape matching was measured using the Kiki-Bouba Test administered with the "Martian language" protocol, and between-group comparisons were analyzed using chi-square tests, supplemented by multivariable logistic regression models to control for age and language ability. The analyses revealed a statistically significant difference between the groups in their sound-shape matching preferences [χ² (1) = 4.286, p < .05; Cramer's V = .267]. While 60% of TD children exhibited the typical matching pattern (spiky-kiki), 66.7% of children in the SSD group showed a reversed tendency, labeling spiky shapes as "bouba" and rounded shapes as "kiki." No significant relationship was found between SSD severity and matching performance. These findings raise the possibility that SSD may involve differences in the multimodal representation of speech sounds that extend beyond motor output alone. Given the single-trial design and sample size, these interpretations should be regarded as preliminary. Pending replication with larger samples and multi-trial frameworks, the Kiki-Bouba Test may offer potential as a supplementary behavioral indicator within SSD assessment and triage protocols.