A stimulus or trigger that activates a stored memory
Encoding Specificity Principle - Endel Tulving
The cues available at recall need to be the same specific cues that were there at learning.
Context-Dependent Forgetting
The tendency to forget information in a particular context or setting, even if you remember it well in another context.
State-Dependent Forgetting
The tendency to forget information that you learned while in a particular emotional state, such as stress or relaxation, when you are in a different emotional state.