Auditory–visual stimulus pairing enhances perceptual learning in a songbird

In many oscine birds, song learning is affected by social variables, for example the behaviour of a tutor. This implies that both auditory and visual perceptual systems should be involved in the acquisition process. To examine whether and how particular visual stimuli can affect song acquisition, we tested the impact of a tutoring design in which the presentation of auditory stimuli (i.e. species-specific master songs) was paired with a well-defined nonauditory stimulus (i.e. stroboscope light flashes: Strobe regime). The subjects were male hand-reared nightingales, Luscinia megarhynchos. For controls, males were exposed to tutoring without a light stimulus (Control regime). The males' singing recorded 9 months later showed that the Strobe regime had enhanced the acquisition of song patterns. During this treatment birds had acquired more songs than during the Control regime; the observed increase in repertoire size was from 20 to 30% in most cases. Furthermore, the copy quality of imitations acquired during the Strobe regime was better than that of imitations developed from the Control regime, and this was due to a significant increase in the number of 'perfect' song copies. We conclude that these effects were mediated by an intrinsic component (e.g. attention or arousal) which specifically responded to the Strobe regime. Our findings also show that mechanisms of song learning are well prepared to process information from cross-modal perception. Thus, more detailed enquiries into stimulus complexes that are usually referred to as social variables are promising. Copyright 1999 The Association for the Study of Animal Behaviour.