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Main Authors: Wild, Cody, Anderson, Jesper
Format: Preprint
Published: 2024
Subjects:
Online Access:https://arxiv.org/abs/2407.07848
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author Wild, Cody
Anderson, Jesper
author_facet Wild, Cody
Anderson, Jesper
contents Previous work has demonstrated that MLPs within ReLU Transformers exhibit high levels of sparsity, with many of their activations equal to zero for any given token. We build on that work to more deeply explore how token-level sparsity evolves over the course of training, and how it connects to broader sparsity patterns over the course of a sequence or batch, demonstrating that the different layers within small transformers exhibit distinctly layer-specific patterns on both of these fronts. In particular, we demonstrate that the first and last layer of the network have distinctive and in many ways inverted relationships to sparsity, and explore implications for the structure of feature representations being learned at different depths of the model. We additionally explore the phenomenon of ReLU dimensions "turning off", and show evidence suggesting that "neuron death" is being primarily driven by the dynamics of training, rather than simply occurring randomly or accidentally as a result of outliers.
format Preprint
id arxiv_https___arxiv_org_abs_2407_07848
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Uncovering Layer-Dependent Activation Sparsity Patterns in ReLU Transformers
Wild, Cody
Anderson, Jesper
Machine Learning
Artificial Intelligence
Previous work has demonstrated that MLPs within ReLU Transformers exhibit high levels of sparsity, with many of their activations equal to zero for any given token. We build on that work to more deeply explore how token-level sparsity evolves over the course of training, and how it connects to broader sparsity patterns over the course of a sequence or batch, demonstrating that the different layers within small transformers exhibit distinctly layer-specific patterns on both of these fronts. In particular, we demonstrate that the first and last layer of the network have distinctive and in many ways inverted relationships to sparsity, and explore implications for the structure of feature representations being learned at different depths of the model. We additionally explore the phenomenon of ReLU dimensions "turning off", and show evidence suggesting that "neuron death" is being primarily driven by the dynamics of training, rather than simply occurring randomly or accidentally as a result of outliers.
title Uncovering Layer-Dependent Activation Sparsity Patterns in ReLU Transformers
topic Machine Learning
Artificial Intelligence
url https://arxiv.org/abs/2407.07848