  Current state-of-the-art neural dialogue systems are mainly data-driven and
are trained on human-generated responses. However, due to the subjectivity and
open-ended nature of human conversations, the complexity of training dialogues
varies greatly. The noise and uneven complexity of query-response pairs impede
the learning efficiency and effects of the neural dialogue generation models.
What is more, so far, there are no unified dialogue complexity measurements,
and the dialogue complexity embodies multiple aspects of
attributes---specificity, repetitiveness, relevance, etc. Inspired by human
behaviors of learning to converse, where children learn from easy dialogues to
complex ones and dynamically adjust their learning progress, in this paper, we
first analyze five dialogue attributes to measure the dialogue complexity in
multiple perspectives on three publicly available corpora. Then, we propose an
adaptive multi-curricula learning framework to schedule a committee of the
organized curricula. The framework is established upon the reinforcement
learning paradigm, which automatically chooses different curricula at the
evolving learning process according to the learning status of the neural
dialogue generation model. Extensive experiments conducted on five
state-of-the-art models demonstrate its learning efficiency and effectiveness
with respect to 13 automatic evaluation metrics and human judgments.
