Physiological constraints and cognitive chunking in Zebra Finch songs: Data and R script

Learned bird songs often have a hierarchical organization. In the case of
zebra finches, each bird’s song is made up of a string of notes delivered
in a stereotyped sequence to form a “motif”, and motifs are repeated to
form a song bout. During song learning, young males copy “chunks” of two
or more consecutive notes from their tutors’ songs. These chunks are
represented as distinct units within memory (during learning) and within
motor systems (during song production). During song performance, motifs
may deviate from the learned sequence by stopping short, starting late, or
by skipping, inserting or repeating notes. We measured acoustic and
temporal variables related to the respiratory and vocal physiology of song
production and asked how they related to deviations from each bird’s
“canonical” sequence. The best predictor of deviations from that sequence
was the duration of the silent interval between notes, when inspiration
normally occurs. Deviations from the canonical motif occurred less often
after higher-pitched notes, perhaps because a high-low sequence forms a
prosodic unit. Premature stops often followed louder and longer notes,
suggesting that respiratory and muscular physiology influence the location
of such stops. Boundaries between the learned chunks of a male’s motif
predicted where and how often non-canonical starts occurred. Physiological
and cognitive elements also interacted to define the segmentation of zebra
finch song sequences. Long silent intervals between notes were associated
both with physiology (inspirations) and with the cognitive boundaries of
learned chunks – and hence with deviations from the canonical motif.