How do wild horses perceive humans when first encountered?

A wild horse encountering a human for the first time perceives the human as a predator — specifically, as a stimulus that activates the same threat-assessment and flight-preparation neurological sequence that a mountain lion or wolf on the range would have triggered. This is not irrationality or confusion on the horse's part; it is the accurate functioning of a threat-detection system that has been maintained by natural selection for the simple reason that horses that treated large, upright-walking animals as safe were more likely to be killed by mountain lions than those that treated them as potential threats until proven otherwise. The human's two-eyed, forward-facing predator gaze, bipedal movement, and unfamiliar scent all contribute to the initial threat assessment, as does any movement toward the horse that resembles a predator's approach — direct, squared-up, and without the submissive, indirect quality that prey animals use when they intend no threat. The specific way the initial threat perception manifests varies between individual horses and between horses from different herds — some horses maintain flight distance from the moment a human enters their space, others will watch from a distance with apparent calm until the human crosses a threshold and then leave explosively. The consistent element is that the wild horse's initial assessment of humans is as predators until the horse's own experience provides convincing evidence otherwise, and no amount of the trainer's benevolent intention changes this initial assessment — only the trainer's behavior, communicated in terms the horse understands, can shift the horse's perception from predator to safe presence. This is why the indirect approach, the avoidance of direct eye contact, and the advance-and-retreat method that gives the horse the experience of choosing to approach rather than being forced to accept are so consistently effective with wild horses across different trainers and traditions.