According to my understanding, ideal utilitarians may be modeled as selfish agents to whom all world states which induce a positive change to another being's utility function induce a proportional positive change to its own utility function, and all world states which induce a negative change to another being's utility function induce a proportional negative change to its own utility function.

My question is regarding the 'proportional' bit -- under the standard definition of utilitarian, would a utilitarian bias its decisions towards helping beings whose utility functions had a greater capacity for increase and decrease (or, in other words, beings who felt more strongly than others?)