Abstract Group living is of benefit to foraging individuals by improving their survival, through passive risk dilution by sheer numbers and through increasingly more active processes, ranging from cue transmission to alarm calling. Cue transmission of information within a group cannot easily be tracked in the field, but can be studied by modelling. An unintentional visual cue can be given by a fleeing action, and when it occurs in the visual field of an individual, can by contagion incite it to flee as well, making such a cue functional in anti-predator warning. The visual field is limited not only by morphology, causing a blind angle at the back, but also by behaviour. For instance, foraging with the head down can cause an extra “blind” angle in front for cues from other individuals, changing an unobstructed frontal visual field to a split lateral shape. The questions of the present study are: how do visual fields, in terms of their size and blind angles, influence survival of individuals in a group through their effect on non-attentional reception of cues to danger among group members after attentional detection of a predator, and how can we quantify this? We use an agent-based spatially explicit model to investigate the effect of contagious fleeing after detection of predators on survival rate. This model is a bottom-up model of foraging agents in a simple environment, where only assumptions about basic competences are made. We vary the size and the shape of the visual field (lateral, with the additional frontal “blind” angle, versus a frontal continuous view), the group size, the movement probability, and the style of movement (regular movement or start-stop movement) in residential groups. We devise a measure for the transmission rate and we measure the length of the transmission chains. We find that, as expected, in a residential group, a larger visual field enhances survival rate. Moreover, a lateral field is more effective than a frontal field of the same total size because it increases the field of vision and therefore the non-attentional reception of visual cues about danger during, for instance, foraging, for all but the largest visual fields. This is demonstrated by the higher transmission rates and longer chains of transmission for lateral fields. Better transmission for lateral visual fields results in more synchronized fleeing behaviour. As long as the visual field is large enough, having a blind angle in front does not detract from sufficiently effective transmission. These findings should be taken into account in empirical studies of vigilance in groups of foraging animals.

中文翻译：

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捕食群体中非注意视觉信息传递的建模

摘要 群体生活有利于个体觅食，方法是提高个体的生存率，通过数量庞大的被动风险稀释，以及通过越来越多的主动过程，从提示传输到警报呼叫。组内信息的提示传输在现场不容易跟踪，但可以通过建模进行研究。逃跑动作可以提供无意的视觉提示，当它发生在个人的视野中时，也可以通过传染来煽动它逃跑，使这种提示在反捕食者警告中起作用。视野不仅受到形态的限制，导致后面的死角，而且还受到行为的限制。例如，低头觅食会导致前方有一个额外的“盲”角，以获取其他人的提示，将无障碍的正面视野改变为分裂的横向形状。本研究的问题是：视野（就其大小和盲角而言）如何通过其对捕食者的注意检测后群体成员对危险线索的非注意接收的影响来影响群体中个体的生存，我们如何量化这一点？我们使用基于代理的空间显式模型来研究检测到捕食者后传染性逃跑对存活率的影响。该模型是一个简单环境中觅食代理的自下而上模型，其中只对基本能力进行假设。我们改变视野的大小和形状（横向，带有额外的正面“盲”角，而不是正面连续视图）、组大小、运动概率、以及居住群体的运动方式（有规律的运动或起停运动）。我们设计了一种传输速率的测量方法，并测量了传输链的长度。我们发现，正如预期的那样，在住宅组中，更大的视野可以提高存活率。此外，横向视野比具有相同总大小的正面视野更有效，因为它增加了视野，因此在例如觅食期间对危险的视觉提示的非注意接收，除了最大视野之外的所有视野. 横向场更高的传输速率和更长的传输链证明了这一点。横向视野更好的传输导致更同步的逃跑行为。只要视野够大，前面有一个死角不会影响足够有效的传输。在对觅食动物群体的警惕性进行实证研究时，应考虑到这些发现。