The decision to investigate or run away upon seeing what I thought was a monster would depend on several factors. If I felt threatened or in immediate danger, my instinct would likely be to run away to ensure my safety. Our natural fight-or-flight response often leans toward self-preservation.
However, if I believed there was a chance it could be a misunderstanding—perhaps it was an animal, a person in a costume, or even a trick of the light—curiosity might prompt me to investigate further. In that case, I would try to assess the situation from a safe distance, ensuring I had an escape route if necessary.
Ultimately, the choice would hinge on the specific context: the behavior of the creature, my location, and my resources for dealing with the situation. Balancing curiosity with caution is crucial when faced with something that appears frightening or unknown.