Humans Consulting HCH (HCH) is a recursive acronym describing a setup where humans can consult simulations of themselves to help answer questions. It is a concept used in discussion of the iterated amplification proposal to solve the alignment problem.

It was first described by Paul Christiano in his post Humans Consulting HCH:

Consider a human Hugh who has access to a question-answering machine. Suppose the machine answers question Q by perfectly imitating how Hugh would answer question Q, if Hugh had access to the question-answering machine.

That is, Hugh is able to consult a copy of Hugh, who is able to consult a copy of Hugh, who is able to consult a copy of Hugh…

Let’s call this process HCH, for “Humans Consulting HCH.”