Relevance and category scales of judgement.

Once adaptation levels had been established in category judgements of the height and lightness of a series of grey blocks, a tall, light block was introduced, and presented with each of the series. Half of the subjects were instructed to reject any block which was lighter than it, and half to reject only those taller. After each decision both groups categorized height and lightness as before. Shifts in scales of judgement were associated with differences in the relevant attributes of the standard.