摘要
This study investigates behavioural lateralization in sheep and lambs of different ages. A flock was tested in a task in which the animals were facing an obstacle and should avoid it on either the right or left side to rejoin flock-mates (adult sheep) or their mothers (lambs). A bias for avoiding the obstacle on the right side was observed, with lambs apparently being more lateralized than sheep. This right bias was tentatively associated with the left-hemifield laterality in familiar faces recognition which has been documented in this species. Differences between adult sheep and lambs were likely to be due to differences in social reinstatement motivation elicited by different stimuli (flock-mates or mothers) at different ages. Preferential use of the forelegs to step on a wood-board and direction of jaw movement during rumination was also tested in adult animals. No population bias nor individual-level lateralization was observed for use of the forelegs. At the same time, however, there was a large number of animals showing individual-level lateralization for the direction of jaw movement during rumination even though there was no population bias. These findings highlight that within the same species individual- and population-level lateralization can be observed in different tasks. Moreover, the results fit the general hypothesis that population-level asymmetries are more likely to occur in tasks that require social coordination among behaviourally asymmetric individuals.
摘要译文
本研究调查了不同年龄的绵羊和羔羊的行为偏侧化。一群羊在动物面临障碍的任务中进行了测试，应该避免在左边或右边重新加入羊群（成年绵羊）或其母亲（羔羊）。观察到避免右侧障碍的偏见，羔羊显然比绵羊更偏侧化。这个正确的偏见暂时与在这个物种中已经记载的熟悉面部识别中的左半侧偏侧有关。成年绵羊和羔羊之间的差异可能是由于不同年龄段的不同刺激（群体或母亲）引起的社会恢复动机的差异。在成年动物中还测试了优先使用前腿踩踏木板和反刍期间下颚运动的方向。前腿的使用没有观察到人口偏差和个体水平偏侧化。然而，与此同时，虽然没有人口偏好，但是有大量的动物在反刍的下颚运动方向上出现了个体化的偏侧化。这些发现强调，在同一物种内，可以在不同的任务中观察到个体和群体水平的侧向化。此外，结果符合这样的一般假设：人口水平不对称更有可能发生在需要行为不对称的个体之间的社会协调的任务中。
ElisabettaVersace[a];MassimoMorgante[b];GiuseppePulina[c];GiorgioVallortigara[a];. Behavioural lateralization in sheep (Ovis aries)[J]. Behavioural Brain Research, 2007,184(1): 72-80