The rise of powerful Transformer-based language models (LMs) and their widespread use highlights the need to investigate their inner workings. Understanding these mechanisms in advanced ai systems is crucial to ensure their safety and fairness, and minimize bias and errors, especially in critical contexts. Consequently, there has been a notable increase in research within the natural language processing (NLP) community, specifically aimed at interpretability in language models, yielding new insights into their internal operations.
Existing surveys detail a variety of techniques used in explainable ai analyzes and their applications within NLP. While previous surveys predominantly focused on encoder-based models like BERT, the emergence of decoder-only Transformers spurred advances in the analysis of these powerful generative models. At the same time, research has explored trends in interpretability and their connections to ai safety, highlighting the evolving landscape of interpretability studies in the NLP domain.
Researchers from the Universitat Politècnica de Catalunya, CLCG, University of Groningen and FAIR, Meta present the study that offers an exhaustive technical description of the techniques used in the investigation of LM interpretability, emphasizing the knowledge obtained from the internal operations of the models and establishing connections between domains of interpretability research. Employing a unified notation, it presents model components, interpretability methods, and insights from the works studied, clarifying the logic behind specific method designs. The discussed LM interpretability approaches are classified along two dimensions: locating model inputs or components for predictions and decoding information within learned representations. Additionally, they provide an extensive list of insights into transformer-based LM operation and describe useful tools for performing interpretability analyzes on these models.
Researchers present two different types of methods that allow localization of model behavior: input attribution and model component attribution. Input attribution methods estimate token importance using gradients or perturbations. Context-matching alternatives to attention weights provide insight into symbolic attributions. Logit attribution measures the contributions of components, while causal interventions view calculations as causal models. Circuit analysis identifies interacting components, and recent advances automate circuit discovery and abstract causal relationships. These methods provide valuable information about the performance of the language model, which helps improve the model and interpretability efforts. Early research on Transformer LMs revealed poor capabilities, where even removing a significant portion of the attention heads may not harm performance. Direct logit attributions (DLA) measure the contribution of each LM component to the token prediction, facilitating analysis of model behavior. Causal interventions view LM calculations as causal models, intervening to measure the effects of components on predictions. Circuit analysis identifies interacting components, which helps understand LM functioning, although it presents challenges such as input template design and compensatory behavior. Recent approaches automate circuit discovery, improving interpretability.
They explore methods for decoding information in neural network models, especially in natural language processing. The probe uses supervised models to predict input properties from intermediate representations. Linear interventions delete or manipulate features to understand their importance or direct model results. Sparse autoencoders disentangle features in models with overlap, promoting interpretable representations. Closed SAEs improve feature detection in SAEs. Decoding in vocabulary space and maximum activation inputs provide information about the behavior of the model. Natural language explanations of LMs offer plausible justifications for predictions, but may lack fidelity to the internal workings of the model. They also provided an overview of several open source software libraries (Captum, a library in the Pytorch ecosystem that provides access to various gradient and perturbation-based input attribution methods for any Pytorch-based model) that were introduced. to facilitate interpretability studies in Transformer- LM based on
In conclusion, this comprehensive study underscores the imperative of understanding the inner workings of Transformer-based language models to ensure their safety, fairness, and mitigate biases. Through a detailed examination of interpretability techniques and insights gained from model analyses, the research contributes significantly to the changing landscape of ai interpretability. By categorizing interpretability methods and showing their practical applications, the study advances the understanding of the field and facilitates continued efforts to improve model transparency and interoperability.
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Asjad is an internal consultant at Marktechpost. He is pursuing B.tech in Mechanical Engineering at Indian Institute of technology, Kharagpur. Asjad is a machine learning and deep learning enthusiast who is always researching applications of machine learning in healthcare.
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