Composite scores for concurrent behaviours constructed using canonical discriminant analysis

Abstract

0003-3472/$38.00 The Association for the Study of A doi:10.1016/j.anbehav.2008.12.011 An animal’s response to a given stimulus may be assessed by measuring more than one type of behaviour. For example, in studies of the chemosensory-based preferences of squamate reptiles for prey organisms, both the frequency of tongue flicking, a behaviour linked to vomerolfaction, and the attempted ingestion of prey-scented objects have been measured. Burghardt (1969; cf. Cooper & Burghardt 1990) proposed combining both tongue-flick counts and biting attacks on scent-laden swabs into a composite index, called the tongue flick–attack score, by which overall preferences for prey-derived chemicals could be compared. In Burghardt’s scheme, an attack, which presumably reflects greater interest in prey-derived cues, was arbitrarily accorded a value equal in weight to the highest number of tongue-flicks displayed by any nonattacking subject to any condition, plus the number of seconds in a trial minus the attack latency. If scores were log-transformed, a value of one was added prior to transformation.