Transformer neural networks have outpaced previous architectures and become the foundation for cutting-edge language models.
Below are the key differences between transformers and other neural networks:
1. Self-attention
The self-attention mechanism simultaneously evaluates relationships between all elements in a sequence (such as words in a text). This enables the model to grasp the global context, even when elements are far apart.
In contrast, RNN/LSTM architectures process data sequentially, making it harder to capture long-range dependencies due to the vanishing gradient problem. CNN models, on the other hand, focus on local patterns (such as n-grams), but often overlook broader contextual relationships.
2. Parallel processing
Transformers leverage matrix operations to process entire sequences in parallel, significantly speeding up training compared to RNNs and LSTMs that process data sequentially. For example, when working with a sentence of 10 words, a transformer can process all words at once, while an RNN would handle them one by one over 10 steps.
3. Non-recurrent architecture
Transformers are built on an encoder-decoder structure, where both components consist of layers of self-attention and feed-forward neural networks.
Unlike traditional models, transformers do not rely on recurrent (RNN) or convolutional (CNN) blocks as their core building elements.
4. Positional encoding
Since transformers process all elements in parallel rather than sequentially, they need a way to capture the order of elements in a sequence. This is achieved through positional embeddings—special vectors (e.g., sinusoidal functions or trainable embeddings). In contrast, RNNs and LSTMs inherently account for order through step-by-step processing.
5. Scalability
Transformers handle large datasets efficiently and scale well on GPUs/TPUs due to their parallel processing capabilities. This scalability has paved the way for the development of massive models like GPT-4, BERT and T5.
Originally designed for machine translation tasks, transformers now dominate areas like text generation, classification, summarization, and even computer vision.