Before discussing how to avoid causing pain to animals, it must be clear: any behavior that intentionally causes pain to animals may violate animal welfare ethics and even violate the law. Scientific research has shown that animals (especially mammals and birds) have the ability to perceive pain and fear, so we should always treat them with respect for life. The following are common indirect stressors analyzed from the perspective of animal behavior and psychology (for reference only, please do not practice)： **1. Environmental deprivation type pressure** -Restrict the space for natural behavior (such as keeping migratory birds in small cages for a long time) -Deprivation of sensory stimulation (raising experimental mice in a completely dark/silent environment) - Making unpredictable noise (decibels that are harmless to humans may overload the canine auditory system) **2. Destruction of social relations** -Separation of maternal and infant individuals (primates and elephants will cause long-term psychological trauma as a result) -Disrupt the group level (there will be persistent conflicts among social animals such as wolves and chickens) -Restrict social interaction (companion animals such as parrots may self-harm) **3. Means of cognitive interference** -Create contradictory conditioned reflexes (random reward/punishment mechanisms cause behavioral disorders in experimental animals) -Blocking habitual paths (forcing migratory animals to change their established routes of activity) -Continuous environmental changes (reptiles are stressed due to the inability to establish territory markers) **4. Circadian rhythm intervention** -Frequent disruption of the light cycle (affecting the metabolic rhythm of rodents) -Irregular feeding system (the digestive system of herbivores may be disturbed as a result) -Artificially create seasonal disturbances (interfere with the hibernation cycle of amphibians) **Precautions：** Although the above behaviors did not cause direct physical harm, they were all recognized as "psychological abuse" by modern animal welfare laws. The EU Directive 2010/63/EU clearly stipulates that the environment of experimental animals must meet the "five freedoms" (freedom from hunger, thirst, discomfort, pain and injury, fear and stress, and expression of nature). Suggest an alternative： -Use VR technology to simulate animal behavior experiments -Monitor physiological indicators through non-invasive sensors -Apply positive reinforcement training instead of traditional domestication methods Human understanding of animal psychological pain is still developing. The latest neuroscience research has found that invertebrates such as octopuses also show complex emotional responses. This reminds us that we should always be in awe of life.