This study explores the fundamental aspects of acquired equivalence learning, where equivalence develops between seemingly unrelated stimuli due to shared consequences. The Rutgers Acquired Equivalence Test (RAET) is a paradigm developed to investigate visually guided equivalence learning, consisting of a learning phase and a test phase. The basal ganglia-frontal cortex pathways play a key role in the learning phase, and the test phase is linked to the functions of the hippocampus-medial temporal lobe.We developed three additional learning tests that differ in the complexity or modality of the applied sensory stimuli but have the same structure as the original RAET.The research aimed to discern whether stimulus complexity or modality has a greater impact on learning different stimulus pairs and the subsequent processes of retrieval and generalization to new pairs in acquired equivalence learning.We involved 117 healthy, adult volunteers in the study. Our results indicated that both the stimulus modality and the visual stimulus complexity significantly influenced the acquired equivalence learning, with complexity having a mean effect on the learning perfromances in acquisition, retriveal and generalization functions.Our findings suggest that, in associative learning, the complexity of stimuli and its resulting better verbalizability primarily determine learning performance, while the efficiency of this learning form is less dependent on the modality of the sensory stimuli.