Data for: Bottlenose dolphins engaging in more social affiliative behaviour judge ambiguous cues more optimistically

Cognitive bias tests measure variation in emotional appraisal and are validated methods to evaluate animals’ affective states. However, the link between social behaviours and cognitive bias has not yet been investigated. Bottlenose dolphins are a gregarious species for whom welfare research is increasing in importance, and thus are a good model to test such an association. We adapted a spatial location judgement bias test for eight captive bottlenose dolphins to investigate the link between cognitive bias and social behaviour, where we conducted behavioural observations outside of training sessions and did not experimentally induce an affective state. Subjects showed stable individual differences in cognitive biases across the three test days. Furthermore, dolphins showing more synchronous swimming, a fundamental affiliative behaviour, judged ambiguous cues significantly more optimistically. Our longer-term data showed cognitive bias and synchronous swimming frequency were significantly associated for up to two months preceding the test, but disappeared prior to that, suggesting that here cognitive bias differences were reflected by transitory affective states rather than longer-term traits. We hypothesise that conducting synchronous swimming may induce affective states and/or be induced by them; either way, it has strong potential as an indicator of affective state in this species and beyond.

认知偏差测试（Cognitive bias tests）是经过验证的评估动物情感状态的方法，可量化情绪评估的变异程度。然而，目前尚未有研究探讨社会行为与认知偏差之间的关联。宽吻海豚是群居性物种，其动物福利研究的重要性与日俱增，因此是检验此类关联的理想模型。本研究针对8只圈养宽吻海豚，调整了空间位置判断偏差测试范式，以探究认知偏差与社会行为之间的关联。实验过程中，我们在训练时段之外开展行为观察，且未通过实验手段诱导动物产生特定情感状态。受试个体在三次测试周期中均表现出稳定的认知偏差个体差异。此外，展现出更频繁同步游泳——这是一种核心的亲和社会行为——的海豚，对模糊线索的判断显著更偏向乐观。我们的长期数据显示，在测试前最多两个月内，认知偏差与同步游泳频率存在显著关联，但在此更早的时段则无此关联，这表明本研究中的认知偏差差异由暂时性情感状态所反映，而非长期特质。我们提出假说：同步游泳行为既可能诱发情感状态，也可能由情感状态所引发；无论何种机制，该行为都极有可能作为该物种乃至其他物种情感状态的有效评估指标。