For some purposes, a bilateral measure such as the mutual information or category utility is more appropriate than the cue validity.
Then we can inquire what the validity of this cue is with regard to the following classes: {rational number, irrational number, even integer}: In perception, "cue validity" is often short for ecological validity of a perceptual cue, and is defined as a correlation rather than a probability (see above).
In this definition, an uninformative perceptual cue has an ecological validity of 0 rather than 0.5.
In much of the work on modeling human category learning, there has been the assumption made (and sometimes validated) that attentional weighting tracks the cue validity, or tracks some related measure of feature informativeness.
This would imply that attributes are differently weighted by the perceptual system; informative or high-cue validity attributes being weighted more heavily, while uninformative or low-cue validity attributes are weighted more lightly or ignored altogether (see, e.g., Navarro 1998).