Memorization Inheritance in Sequence-Level Knowledge Distillation for Neural Machine Translation

Fuente: arXiv
Saved in:
Bibliographic Details
Main Authors: Dankers, Verna, Raunak, Vikas
Format: Preprint
Published: 2025
Subjects:
Online Access:
Tags: Add Tag
No Tags, Be the first to tag this record!
_version_ 1866911060958642176
author Dankers, Verna
Raunak, Vikas
author_facet Dankers, Verna
Raunak, Vikas
contents In this work, we explore how instance-level memorization in the teacher Neural Machine Translation (NMT) model gets inherited by the student model in sequence-level knowledge distillation (SeqKD). We find that despite not directly seeing the original training data, students memorize more than baseline models (models of the same size, trained on the original data) -- 3.4% for exact matches and 57% for extractive memorization -- and show increased hallucination rates. Further, under this SeqKD setting, we also characterize how students behave on specific training data subgroups, such as subgroups with low quality and specific counterfactual memorization (CM) scores, and find that students exhibit amplified denoising on low-quality subgroups. Finally, we propose a modification to SeqKD named Adaptive-SeqKD, which intervenes in SeqKD to reduce memorization and hallucinations. Overall, we recommend caution when applying SeqKD: students inherit both their teachers' superior performance and their fault modes, thereby requiring active monitoring.
format Preprint
id arxiv_https___arxiv_org_abs_2502_01491
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Memorization Inheritance in Sequence-Level Knowledge Distillation for Neural Machine Translation
Dankers, Verna
Raunak, Vikas
Computation and Language
In this work, we explore how instance-level memorization in the teacher Neural Machine Translation (NMT) model gets inherited by the student model in sequence-level knowledge distillation (SeqKD). We find that despite not directly seeing the original training data, students memorize more than baseline models (models of the same size, trained on the original data) -- 3.4% for exact matches and 57% for extractive memorization -- and show increased hallucination rates. Further, under this SeqKD setting, we also characterize how students behave on specific training data subgroups, such as subgroups with low quality and specific counterfactual memorization (CM) scores, and find that students exhibit amplified denoising on low-quality subgroups. Finally, we propose a modification to SeqKD named Adaptive-SeqKD, which intervenes in SeqKD to reduce memorization and hallucinations. Overall, we recommend caution when applying SeqKD: students inherit both their teachers' superior performance and their fault modes, thereby requiring active monitoring.
title Memorization Inheritance in Sequence-Level Knowledge Distillation for Neural Machine Translation
topic Computation and Language
url https://arxiv.org/abs/2502.01491