Revisiting Distillation for Continual Learning on Visual Question
  Localized-Answering in Robotic Surgery
Long Bai Mobarakol Islam Hongliang Ren
The visual-question localized-answering (VQLA) system can serve as a
knowledgeable assistant in surgical education. Except for providing text-based
answers, the VQLA system can highlight the interested region for better
surgical scene understanding. However, deep neural networks (DNNs) suffer from
catastrophic forgetting when learning new knowledge. Specifically, when DNNs
learn on incremental classes or tasks, their performance on old tasks drops
dramatically. Furthermore, due to medical data privacy and licensing issues, it
is often difficult to access old data when updating continual learning (CL)
models. Therefore, we develop a non-exemplar continual surgical VQLA framework,
to explore and balance the rigidity-plasticity trade-off of DNNs in a
sequential learning paradigm. We revisit the distillation loss in CL tasks, and
propose rigidity-plasticity-aware distillation (RP-Dist) and self-calibrated
heterogeneous distillation (SH-Dist) to preserve the old knowledge. The weight
aligning (WA) technique is also integrated to adjust the weight bias between
old and new tasks. We further establish a CL framework on three public surgical
datasets in the context of surgical settings that consist of overlapping
classes between old and new surgical VQLA tasks. With extensive experiments, we
demonstrate that our proposed method excellently reconciles learning and
forgetting on the continual surgical VQLA over conventional CL methods. Our
code is publicly accessible.