Interaction between lateralized systems: exploring the complexity of laterality.

To assess the extent of interaction between lateral biases in response systems at different levels of the neuraxis and detect the possible presence of different patterns of interaction related to population subgroups, we investigated laterality in hand reaching, whole-body turning and eye use in 20 bushbabies (Otolemur garnettii). Two subgroups were clearly identified: the STABLE group was composed of subjects, mainly females, that were consistent in hand preference and had correlation of hand/eye bias; the UNSTABLE group included subjects, mainly males, that showed instability in hand preference as a function of change in test conditions and had correlation of hand/turning bias. Results are interpreted to support the value of the study of interaction between lateral biases as a way of gaining a deeper understanding of the complexity of laterality.