Jehovah's Witnesses teach that holy spirit acts as a remembrancer, enabling a person to remember things he studied in the past on the spur of the moment when he needs it. Jehovah's Witnesses pray for holy spirit to direct their meetings and believe that there is holy spirit in operation during their meetings.
But have you noticed how, during a question and answer discussion, the brother on the platform would sometimes forget the names of persons in the audience - persons he knows very well? You would think that holy spirit would at least enable them to remember the name of someone they have seen and spoken to every week at the meeting for years!
The reason they forget the names of persons they know very well when on the platform, is that their mental attention and memory resources are so taxed with dealing with the assignment at hand, that the brain sometimes lapses in recalling other very simple but unrelated information - sometimes something as simple as the name of someone in the audience that they actually know very well.
If they truly had the help of holy spirit the brain would be helped and such lapses wouldn't occur. It's all human efforts.