Positional Heads
Positional heads is the attention heads whose behavior is dominated by relative or absolute positional relationships between tokens - they provide structured position-aware routing that other circuits rely on.
What Is Positional heads?
- Definition: Heads show strong preference for fixed positional offsets or position classes.
- Role: Encode ordering and distance information for downstream computations.
- Variants: Includes previous-token, next-token, and long-range offset-focused patterns.
- Detection: Observed via relative-position attention histograms and ablation impact.
Why Positional heads Matters
- Sequence Structure: Position-aware routing is necessary for order-sensitive language behavior.
- Circuit Foundation: Many semantic and syntactic circuits build on positional primitives.
- Generalization: Robust position handling supports long-context behavior quality.
- Failure Debugging: Positional drift can explain context-length degradation and misalignment.
- Architecture Study: Useful for comparing positional-encoding schemes across models.
How It Is Used in Practice
- Offset Profiling: Quantify attention preference by relative token distance.
- Long-Context Tests: Evaluate positional-head stability as sequence length grows.
- Ablation: Remove candidate heads to measure order-sensitivity degradation.
Positional heads is a key positional information channel inside transformer attention - positional heads are essential infrastructure for reliable sequence-order reasoning in language models.