 The components of FLB that HCF hypothesize are not part of FLN are the “sensory-motor” and “conceptual-intentional” systems. The study of the conceptual-intentional system includes investigations of things like the theory of mind; referential vocal signals; whether imitation is goal directed; and the field of pragmatics. The study of the sensory motor system, by contrast, includes “vocal tract length and formant dispersion in birds and primates”; learning of songs by songbirds; analyses of vocal dialects in whales and spontaneous imitation of artificially created sounds in dolphins; “primate vocal production, including the role of mandibular oscillations”; and “[c]ross-modal perception and sign language in humans versus unimodal communication in animals”.