HiLIFE Helsinki Institute of Life Science, University of Helsinki, Helsinki, Finland.
Research Programme in Organismal and Evolutionary Biology, Faculty of Biological and Environmental Sciences, University of Helsinki, Helsinki, Finland.
Anim Cogn. 2020 Sep;23(5):1007-1018. doi: 10.1007/s10071-020-01407-x. Epub 2020 Jul 3.
Colours are commonly used as visual cues when measuring animals' cognitive abilities. However, animals can have innate biases towards certain colours that depend on ecological and evolutionary contexts, therefore potentially influencing their performance in experiments. For example, when foraging, the colour red can advertise profitable fruits or act as a warning signal about chemically defended prey, and an individual's propensity to take food of that colour may depend on experience, age or physical condition. Here, we investigate how these contexts influence blue tits' (Cyanistes caeruleus) and great tits' (Parus major) responses to red-coloured almond flakes. We found that juvenile birds preferred red both when it was presented simultaneously with green, and when it was presented with three alternative colours (orange, purple, green). Adult birds, however, only preferred red after a positive experience with the colour, or when it was presented with the three alternative colours. We then tested whether colour influenced avoidance learning about food unpalatability. Despite the prediction that red is a more salient warning signal than green, we found only weak evidence that birds discriminated red unpalatable almonds from a green palatable alternative more quickly than when the colours were reversed. Our results suggest that biases towards red food may depend on birds' age and previous experience, and this might influence their performance in experiments that use red stimuli. Considering the ecological relevance of colours is, therefore, important when designing experiments that involve colour cues.
颜色通常被用作测量动物认知能力的视觉线索。然而，动物可能对某些颜色存在先天的偏见，这些偏见取决于生态和进化背景，因此可能会影响它们在实验中的表现。例如，在觅食时，红色可以表示有利润的水果，或者作为对具有化学防御能力的猎物的警告信号，而个体对那种颜色的食物的偏好可能取决于经验、年龄或身体状况。在这里，我们研究了这些背景如何影响蓝山雀（Cyanistes caeruleus）和大山雀（Parus major）对红色杏仁片的反应。我们发现，当红色与绿色同时出现，或者当红色与三种替代颜色（橙色、紫色、绿色）一起出现时，幼鸟更喜欢红色。然而，成年鸟只有在对颜色有积极的体验后，或者当呈现三种替代颜色时，才会更喜欢红色。然后，我们测试了颜色是否会影响对食物不可口性的回避学习。尽管预测红色是比绿色更显著的警告信号，但我们只发现了微弱的证据表明，与颜色反转相比，鸟类更快地将红色不可口的杏仁与绿色可口的替代物区分开来。我们的研究结果表明，对红色食物的偏见可能取决于鸟类的年龄和以往的经验，这可能会影响它们在使用红色刺激的实验中的表现。因此，在设计涉及颜色线索的实验时，考虑颜色的生态相关性非常重要。
