Using ordinal scales in psychology

It seems common to believe that measures reported by participants in the behavioral sciences attain ordinal but not interval status. We consider three different measurement situations: Where one value is obtained from each of a number of respondents; where the measure is formed from combining other measures; and where the measure is obtained as a result of an observer perceiving stimuli over a period of time. In each case the presumption that the scale is ordinal produces serious theoretical and practical problems. The issue of where a measure is presumed to be located and the possibility that different measures are useable for the same construct are important considerations. The overall conclusion is that scales which are ordinal but not interval are only rarely available or useful in psychology.