Cue validity is the conditional probability that an object falls in a particular category given a particular feature (cue).
Some attributes are considered as more essential for a category than others. Thus, the notion of cue validity implies that attributes are differently weighted; some might be essential, others can be overridden with varying degrees of facility. Essential attributes have the highest cue validity for a certain category (Navarro 1998).
Cue validity is a more specific version of feature validity -- whereas cues tend to be more directly perceivable whereas the term feature includes inferred or "deep" features as well as cues.
Another difference between cue validity and feature validity is that cue validity refers to aspects of the observable stimuli that students experience during learning whereas feature validity refers to aspects of the unobservable knowledge components that students acquire and refine as a consequence of such experiences.