Dogs can tell if you’re scared or sad

狗狗能分辨出你是害怕还是悲伤

Any dog owner would tell you that their canine companions are attuned to their humans’ emotional state and respond accordingly. Scientists have performed fMRI scans on dogs and identified a specific brain region that processes happy human facial expresses, like a smile, according to a new paper published in the journal iScience. They also found that dogs can tell the difference between negative facial expressions, specifically anger, sadness, and fear.

任何养狗的人都会告诉你，他们的犬类伙伴对人类的情绪状态非常敏感，并会做出相应的反应。根据发表在《iScience》杂志上的一篇新论文，科学家们对狗进行了功能性磁共振成像（fMRI）扫描，并确定了大脑中一个专门处理人类快乐面部表情（如微笑）的特定区域。他们还发现，狗能够区分负面的面部表情，特别是愤怒、悲伤和恐惧。

“Humans are really good at picking up small details on the face, and so are dogs,” said co-author Raúl Hernández-Pérez of the University of Vienna. “This makes dogs very interesting. By studying their brains, we can understand what adaptations have developed to support their remarkable social and emotional understanding of humans.”

“人类非常擅长捕捉面部细微的表情，狗也是如此，”维也纳大学的合著者劳尔·埃尔南德斯-佩雷斯（Raúl Hernández-Pérez）说。“这使得狗变得非常有趣。通过研究它们的大脑，我们可以了解它们进化出了哪些适应性，以支持它们对人类非凡的社交和情感理解能力。”

Prior behavioral studies have shown that dogs are sensitive to emotion in human faces. Dogs will, for example, choose a box their human has identified with a happy expression over one the human treats with fear or disgust. Past fMRI studies found that an area in the canine left temporal cortex showed a stronger response to human faces compared to dog faces, as well as a greater response in the caudate, hippocampus, and amygdala to human faces showing emotion versus neutral faces. This latest study sought to use fMRI to unravel the underlying neural correlates of processing human facial expressions in dogs.

之前的行为研究表明，狗对人类面部的情绪很敏感。例如，如果人类用快乐的表情指向一个盒子，而对另一个盒子表现出恐惧或厌恶，狗会选择前者。过去的功能性磁共振成像研究发现，与狗脸相比，犬类左侧颞叶皮层的一个区域对人脸的反应更强烈；此外，在面对表现出情绪的人脸时，它们的尾状核、海马体和杏仁核的反应也比面对中性表情时更强烈。这项最新研究旨在利用功能性磁共振成像，揭示狗处理人类面部表情背后的神经相关性。

For the first experiment, the team recruited eight dogs (six border collies, one labrador, and one gold retriever) who lived with humans and were well-socialized. Seven of the dogs had previously participated in fMRI studies and were trained to sit still in a sphinx position during the scan; the new participant, Molly, underwent training using the same protocol. The researchers provided the dogs with a chin rest to support their heads during the scan and ear muffs for noise protection. No restraints were used. Each dog was randomly shown a series of human faces as stimuli, with either neutral or happy expressions, for seven seconds while in the MRI machine. They used the faces of strangers to rule out any familiarity effects.

在第一个实验中，研究团队招募了八只与人类共同生活且社会化程度良好的狗（六只边境牧羊犬、一只拉布拉多犬和一只金毛寻回犬）。其中七只狗曾参与过功能性磁共振成像研究，并接受过训练，能在扫描过程中保持“狮身人面像”姿势静止不动；新参与者莫莉（Molly）则按照同样的方案接受了训练。研究人员为狗提供了下巴托以支撑头部，并佩戴耳罩以保护听力。实验过程中没有使用任何束缚装置。每只狗在核磁共振仪中时，会被随机展示一系列人类面部图像作为刺激，这些图像要么是中性表情，要么是快乐表情，每张持续七秒。他们使用了陌生人的面孔，以排除任何熟悉度带来的影响。

The resulting analysis showed that the temporal cortex (associated with higher cognitive functions) and the caudate nucleus (associated with reward) had the most activity in response to happy faces.

分析结果显示，颞叶皮层（与高级认知功能相关）和尾状核（与奖励机制相关）在面对快乐表情时最为活跃。

But neural processing of facial expressions doesn’t occur in isolated brain regions; multiple networked regions may be involved, and those regions may respond to other emotions as well. So the team conducted a second set of follow-up experiments involving 12 dogs (one mixed breed, three golden retrievers, and eight border collies). This time they showed the dogs four basic human expressions: happiness, sadness, fear, and anger. The dogs’ brains responded differently to the negative emotions than to the happy faces.

然而，面部表情的神经处理并非发生在孤立的大脑区域；多个网络化区域可能参与其中，且这些区域也可能对其他情绪做出反应。因此，研究团队进行了第二组后续实验，涉及12只狗（一只混种犬、三只金毛寻回犬和八只边境牧羊犬）。这一次，他们向狗展示了四种基本的人类表情：快乐、悲伤、恐惧和愤怒。结果发现，狗的大脑对负面情绪的反应与对快乐表情的反应截然不同。

The team next conducted another follow-up experiment with the same 12 dogs, this time using a whole-brain analysis—as opposed to just the right temporal lobe data—to test if the dogs could tell the difference between the three negative human facial expressions. The resulting fMRI scans showed distinct activity patterns for fear, anger, and sadness, suggesting that dogs can distinguish between these facial expressions.

随后，研究团队对同样的12只狗进行了另一项后续实验，这次使用了全脑分析（而非仅限于右颞叶数据），以测试狗是否能区分这三种负面的人类面部表情。所得的功能性磁共振成像扫描显示，恐惧、愤怒和悲伤对应着不同的活动模式，这表明狗能够区分这些面部表情。

One caveat is that dogs rely on more than still photographs when they interact with us: They also look for body language cues, vocal nuances, and scent. Stray dogs that don’t hail from loving families might process these cues differently. And just because they can identify happy faces and tell the difference between three basic negative emotions, that doesn’t mean they experience emotions just like human beings.

需要注意的是，狗在与我们互动时，不仅仅依赖静态照片：它们还会观察肢体语言线索、声音细微差别和气味。并非来自充满爱心的家庭的流浪狗，对这些线索的处理方式可能会有所不同。而且，仅仅因为它们能识别快乐的表情并区分三种基本的负面情绪，并不意味着它们体验情绪的方式与人类完全相同。

“When we compare humans with primates, we are looking at abilities that may have come from a common ancestor,” said co-author Laura Cuaya of the University of Vienna. “With dogs, the story is totally different. They followed a very different evolutionary path, yet through domestication, they developed the social abilities needed to understand and cooperate with us. I would like people to see dogs as emotional beings. They have evolved with us to understand our expressions and cooperate with us, and recognizing that can change how we communicate with and care for them.”

“当我们比较人类和灵长类动物时，我们研究的是可能源自共同祖先的能力，”维也纳大学的合著者劳拉·库亚亚（Laura Cuaya）说。“但对于狗来说，情况完全不同。它们走的是一条截然不同的进化道路，然而通过驯化，它们发展出了理解我们并与我们合作所需的社交能力。我希望人们将狗视为有情感的生物。它们与我们共同进化，学会了理解我们的表情并与我们合作，认识到这一点可以改变我们与它们沟通和照顾它们的方式。”