Laddering techniques involve the creation, reviewing and modification of hierarchical knowledge, often in the form of ladders (i.e. tree diagrams).
Here the expert and knowledge engineer both refer to a ladder presented on paper or a computer screen, and add, delete, rename or re-classify nodes as appropriate.
Laddering can also involve a set of predefined probe questions, such as "Could you tell me some sub-types of X?", "Could you tell me how you can tell that something is X?" and "Why would you prefer X to Y?". A leading proponent of this is Dr Gordon Rugg.
Use of Ladders
Various forms of ladder can be used.
For more explanation and examples of ladders, see types of knowledge models.
Other Knowledge Acquisition Techniques:
Protocol Analysis techniques
Repertory Grid technique
Limited-Information and Constrained-Processing tasks