<p>This study examined whether tact and baseline intraverbal training designed to facilitate intraverbal bidirectional naming (I-BiN) would be sufficient to establish derived stimulus–stimulus and intraverbal relations consistent with equivalence classes. Eleven Japanese-speaking university students completed tact training, listener testing, and intraverbal training, followed by testing procedures assessed equivalence class formation via MTS and intraverbal posttests. Ten participants demonstrated emergent responding across both tasks. Vocal MTS posttests revealed that most participants emitted trained or self-generated tacts or intraverbals, suggesting the use of verbal mediation. Latency analyses indicated an early reliance on verbal behavior that diminished over time. Post-experimental interviews confirmed the use of both verbal and visual strategies, including familiarity-based associations and visual imagining. These findings support the sufficiency of I-BiN for equivalence class formation, while highlighting individual variability in mediation strategies. The results underscore the interplay between verbal behavior and visual imagining in the emergence of equivalence relations.</p>