What are the main techniques used in Explainable AI?

Explainable AI (XAI) techniques aim to make machine learning models more transparent and understandable. These methods fall into three broad categories: model-specific approaches, post-hoc explanation methods, and visualization tools. Each addresses different aspects of interpretability, helping developers and stakeholders understand how models make decisions.

Model-specific techniques are tied to particular types of algorithms. For example, decision trees and linear models are inherently interpretable because their structures (e.g., splitting rules or coefficients) directly show how features influence predictions. In contrast, complex models like neural networks or ensemble methods require specialized methods. Attention mechanisms in transformers highlight which input tokens a model focuses on during prediction. For gradient-boosted trees, tools like feature importance scores quantify how much each feature contributes to predictions. Libraries like SHAP (SHapley Additive exPlanations) and LIME (Local Interpretable Model-agnostic Explanations) provide model-agnostic approaches but are often adapted to work with specific architectures.

Post-hoc explanation methods generate insights after a model is trained. LIME, for instance, approximates a complex model locally by training a simpler surrogate model (like a linear regression) on perturbed samples near a specific prediction. SHAP uses game theory to assign each feature a value representing its contribution to the prediction. Partial dependence plots (PDPs) show how a feature affects outcomes by varying its value while holding others constant. Counterfactual explanations, another post-hoc method, describe what changes to input data would alter a prediction (e.g., “If income increased by $10k, the loan would be approved”). These techniques help debug models, identify biases, or comply with regulations like GDPR’s “right to explanation.”

Visualization tools make explanations accessible. Saliency maps highlight input regions (e.g., pixels in an image) most influential to a neural network’s output. Tools like TensorBoard or libraries like Captum (for PyTorch) provide interactive dashboards to explore feature attributions. For text models, techniques like embedding visualization or attention heatmaps reveal how words or phrases drive predictions. Visualization also extends to global model behavior: decision boundaries in 2D plots or t-SNE projections of latent spaces help developers grasp overall model logic. By combining these techniques, developers can iteratively improve models, validate their behavior, and communicate results to non-technical audiences effectively.