Divergent processing strategies for auditory sequence recognition in humans and zebra finches (Taeniopygia guttata)

Deriving sequential information from complex sounds is a challenge for auditory systems, yet it remains unclear whether humans and nonhuman species integrate multidimensional cues or prioritize a single dimension when processing multidimensional input. We investigated how humans and zebra finches (Taeniopygia guttata) process concurrent acoustic cues using an identical behavioural paradigm with complex-tone sequences. By presenting probe stimuli that selectively preserved or disrupted either pitch or formant trajectory, we quantified these processing strategies. We show that zebra finches employ an additive integration strategy, treating pitch and formant trajectories as complementary components of a unified auditory pattern. In contrast, humans exhibit a dominant reliance on pitch. Experience further modulates this bias, with trained human listeners recruiting secondary cues to preserve learned relational structure when pitch is unreliable. These findings imply a cross-species divergence in auditory representation, suggesting that auditory processing is shaped by an interplay of species-specific priorities and experience-dependent functional substitution.