Supplementary Material for: Color discrimination provides insight into the relationship between personality cognition and brain morphology in the of western mosquitofish’s (Gambusia affinis)

Recent studies on the differences in cognitive ability between individuals focused on two aspects: one is whether the individual differences in cognitive ability are related to brain size, the other is whether they pertain to certain personality traits. To explore these two hypotheses, we tested the personality traits, cognitive abilities and brain volumes of western mosquitofish (Gambusia affinis). First, a color preference test was conducted to select two unbiased colors for G. affinis for subsequent cognitive tests. The results showed that G. affinis had a great preference for red and green to yellow and blue, therefore, the red - green combination was selected for the study of cognitive abilities. Then, we explored the relationship among cognition, personality and brain morphology through cognitive abilities tests, personality traits and brain volume measurements. We found that there was a trade-off among cognition, personality and brain morphology. For example, more active individuals found food faster, but have also poor memory; Those individuals with larger corpus cerebelli were bolder while they were less likely to find food; The individuals that found food faster were more active and had a smaller inferior lobe. The color preference test provides a reliable way for selecting unbiased colors for behavioral studies in G. affinis. Meanwhile, our study indicates that there exists a balance mechanism among cognition, personality and brain morphology.

当前针对个体间认知能力差异的研究主要聚焦两大方向：一是认知能力的个体差异是否与脑容量相关，二是该差异是否与特定人格特质存在关联。为验证这两项假说，本研究对西部食蚊鱼（western mosquitofish, Gambusia affinis）的人格特质、认知能力与脑容量展开了检测。首先，本研究开展颜色偏好实验，为西部食蚊鱼筛选出两种无偏向性的颜色以供后续认知测试使用。结果显示，相较于黄色与蓝色，西部食蚊鱼对红色与绿色表现出更强的偏好，因此本研究选取红-绿组合开展认知能力相关研究。随后，本研究通过认知能力测试、人格特质评估与脑形态学测量，探究了认知、人格与脑形态之间的关联，结果发现三者间存在权衡关系。例如，活跃度更高的个体觅食速度更快，但记忆力较差；小脑体（corpus cerebelli）体积更大的个体更胆大，但觅食成功率更低；觅食速度更快的个体活跃度更高，且下叶（inferior lobe）体积更小。本研究的颜色偏好实验为西部食蚊鱼的行为学研究筛选无偏向性颜色提供了可靠方法。同时，本研究证实认知、人格与脑形态之间存在平衡调控机制。