Question

What would have prompted the monkey to look at his own reflection in the mirror

Answer 1

its habit of cheating

Answer 2

Humans are the most intelligent species in the whole world.Rest of species have inferior amount of Intelligence due to their undeveloped brain structure.

That's why if we show a mirror to a monkey,he will get confused after seeing his own reflection.

Because, mirrors are not the natural things in the jungle territory.That's why the monkey will get confused and can even get hyper at some circumstances.