Pornography is no drug.

It is though a type of vessel, a facilitator if you will, for the male brain to release a hormone called oxytocin.

In males, oxytocin has a binding effect. That is, from where the stimulus originates...be it sex with another person, porn, whacking stories (fantasy) etc...the male will make an association to the stimulus and his ensuing orgasm.

A man will naturally bind to whatever, or whomever, causes sexual stimulation and or facilitates his orgasm. Some link it to a specific person, most however make a general link to which gender arouses them. ie...'She makes me orgasm.' vs 'women make me orgasm.'

Or in the case of pornography...'porn makes me orgasm.'