What is the most likely cause of a person squinting in photographs taken at noon?

Squinting in photographs taken at noon is most likely caused by harsh sunlight. At this time of day, the sun is at its highest point in the sky, resulting in direct, intense light that can be overwhelming to the eyes. In order to reduce the amount of light entering the eyes and to manage glare, people instinctively squint. This reflex helps protect the eyes from discomfort and allows for better focus on the subject.

The other situations listed, while they can influence how a person appears in photographs, do not typically lead to squinting in bright sunlight. Low light conditions generally would not cause squinting but might lead to other expressions, such as straining the eyes for better visibility. A reflective surface could cause glare, but it is the intensity of the sunlight itself that most directly triggers squinting behavior. A wide-angle lens affects perspective and field of view in photography but does not influence how light interacts with the subject’s eyes.