Supplementary Material for: The dot-probe attention bias task as a method to assess psychological wellbeing after anesthesia: A study with adult female long-tailed macaques (Macaca fascicularis)

Understanding the impact routine research and laboratory procedures have on animals is crucial to improving their wellbeing and to the success and reproducibility of the research they are involved in. Cognitive measures of welfare offer insight into animals’ internal psychological state, but require validation. Attention bias - the tendency to attend to one type of information over another – is a cognitive phenomenon documented in humans and animals that is known to be modulated by affective state (i.e., emotions). Hence, changes in attention bias may offer researchers a deeper perspective of their animals’ psychological wellbeing. The dot-probe task is an established method for quantifying attention bias in humans (by measuring reaction time to a dot-probe replacing pairs of stimuli), but has yet to be validated in animals. We developed a dot-probe task for long-tailed macaques (Macaca fascicularis) to determine if the task can detect changes in attention bias following anesthesia, a context known to modulate attention and trigger physiological arousal in macaques. Our task included the following features: stimulus pairs of threatening and neutral facial expressions of conspecifics and their scrambled counterparts, two stimuli durations (100 and 1000 ms), and counterbalancing of the dot-probe’s position on the touchscreen (left, right) and location relative to the threatening stimulus. We tested eight group-housed adult females on different days relative to being anesthetized (baseline and one-, three-, seven-, and 14-days after). At baseline, monkeys were vigilant to threatening content when stimulus pairs were presented for 100 ms, but not 1000 ms. On the day immediately following anesthesia, we found evidence that attention bias changed to an avoidance of threatening content. Attention bias returned to threat vigilance by the third day post-anesthesia and remained so up to the last day of testing (14 days after anesthesia). We also found that attention bias was independent of the type of stimuli pair (i.e., whole face vs. scrambled counterparts), suggesting that the scrambled stimuli retained aspects of the original stimuli. Nevertheless, whole faces were more salient to the monkeys as responses to these trials were generally slower than to scrambled stimulus pairs. Overall, our study suggests it is feasible to detect changes in attention bias following anesthesia using the dot-probe task in non-human primates. Our results also reveal important aspects of stimulus preparation and experimental design.

明晰常规研究与实验室操作对实验动物的影响，对于改善动物福利、提升其所参与研究的可靠性与可重复性至关重要。认知福利评估可揭示动物的内在心理状态，但需经过验证后方可采信。注意力偏差（Attention bias）——即优先关注某一类信息而非其他的倾向——是一种已在人类与动物中被证实的认知现象，已知其会受情感状态（即情绪）调控。因此，注意力偏差的变化可为研究者提供洞悉实验动物心理福祉的全新视角。点探测任务（dot-probe task）是一种已成熟应用于人类注意力偏差量化的实验范式——通过测量替换成对刺激的点探测反应时实现，但尚未在动物身上完成有效性验证。本研究针对食蟹猴（Macaca fascicularis）开发了一款点探测任务范式，旨在探究该范式能否检测麻醉后动物的注意力偏差变化——已知麻醉状态可调控食蟹猴的注意力并引发生理唤醒。该任务范式包含以下设计特征：以同种个体的威胁性与中性面部表情及其打乱版图像作为成对刺激，设置两种刺激呈现时长（100 ms与1000 ms），并对触摸屏上点探测的位置（左、右）以及其相对于威胁性刺激的方位进行平衡处理。本研究针对8只群居饲养的成年雌性食蟹猴，在麻醉前后的不同时间点（基线期、麻醉后1天、3天、7天及14天）开展实验测试。在基线期，当刺激对呈现时长为100 ms时，食蟹猴会对威胁性内容表现出警觉性偏向，但在1000 ms时长下则无此现象。在麻醉后的当日，我们观测到注意力偏差转向了对威胁性内容的回避偏向。至麻醉后第3天，食蟹猴的注意力偏差恢复为威胁性警觉偏向，并持续至实验测试的最后一天（麻醉后14天）。此外，我们发现注意力偏差与刺激对的类型（完整面部图像 vs. 打乱版图像）无关，这表明打乱版刺激仍保留了原始刺激的部分特征。不过，完整面部图像对食蟹猴而言更为醒目——因为针对这类试次的反应时普遍长于打乱版刺激对的反应时。综上，本研究表明，利用点探测任务范式可在非人灵长类动物中检测麻醉后的注意力偏差变化。本研究结果同时揭示了刺激制备与实验设计中的若干关键要点。