Scan and focal sampling: reliability in the laterality for maternal cradling and infant nipple preferences in olive baboons, Papio anubis

We compared measures of laterality obtained by two observational sampling procedures (a 15-min focal-dyad sampling with continuous recording, and a scan and instantaneous sampling), using 10 mother-infant dyads of captive olive baboons. The two measures of lateral biases for maternal cradling, infant nipple preference, infant head position and maternal carrying, but not those for infant retrieval, were positively and significantly correlated. Our results clearly show that the two sampling procedures produce equally sensitive measures of lateral bias for both the maternal and the infant behaviours. They also provide evidence of asymmetries in mean bout length and therefore suggest that recording bouts is not necessarily the best measure of lateral bias. Taken together, these results show empirically that the scan and instantaneous sampling procedure does not lead to a lack of independence of data points, as previously assumed.