Does zebra finch (Taeniopygia guttata) preference for the (familiar) father's song generalize to the songs of unfamiliar brothers?

Several studies have demonstrated that zebra finches (Taeniopygia guttata) prefer their fathers' songs over unfamiliar songs. Songs of tutors (i.e., fathers) and tutees (i.e., sons) resemble each other as a result of cultural transmission. Subjects (N = 18) with a previously established preference for the father's song could choose between the song of an unfamiliar brother or a random unfamiliar song in an operant task. Most subjects showed a significant preference for either category of song, but overall, the songs of unfamiliar brothers were not preferred, although they were more similar to the father's song than were the unfamiliar songs. This suggests that subjects did not generalize their learned preference for a song of a particular tutor, to the songs of his tutees.