Auditory regularity detection in the ferret

Abstract

Acoustic sequences that transition from random to regularly repeating tones are increasingly used to study how the auditory system detects structure. Humans can identify such regularities rapidly, often within a single cycle. To test whether this ability is unique to humans, we trained ferrets (n = 6) to detect transitions from random tone sequences to repeating patterns. All animals learned the task and showed high accuracy for short (3 tone) patterns. Performance remained above chance for longer patterns (5 or 7 tones), though accuracy declined with increased pattern length. In a control condition where both random and regular segments contained the same five frequencies, ferrets continued to detect regularity, indicating they relied on temporal patterning rather than spectral content. To further rule out spectral cues, we included transitions from random 20 tone sequences to random 3, 5 or 7 tone sequences without repetition. Although these stimuli elicited performance above the false alarm rate seen in fully random trials, detection accuracy remained substantially lower than that observed for regular sequences. This suggests ferrets were not solely detecting changes in spectral statistics, but true regularity. Together, our results indicate that sensitivity to regular patterns within sound is not unique to humans and may reflect a broader auditory computation shared across species.