I wonder whether using a space metaphor might help. Gigerenzer seems to apply this: drawing from an urn, imainging a population. If you have an equals distribution (base rate 50%) you might use left/right, but this doesn't gain much as 50/50 is already unbiased. How about imagining the more likely candidates in front of you and the other behind you - that will likely put them out of your awareness and thus reducing their saliency. The question is what percentage that represents. The same approach could be used to imagine positive candidates near and negative ones far away.