The development of a self-administered psychophysical scaling method: internal consistency and temporal stability in...

Twenty chronic pain patients carried out a self-administered cross-modal matching task to scale pain intensity and unpleasantness descriptors on 2 occasions separated by 2-3 weeks. Measures of psychological distress (HAD and GHQ) and verbal intelligence (Mill Hill Synonym Test) were also taken. On the 2 occasions 65% and 70% of patients were able to scale intensity words with an internal consistency of r greater than or equal to 0.90. Eleven (55%) patients met this criterion on both occasions. The percentage of patients meeting the internal consistency criterion for unpleasantness descriptors was much lower, 25% and 40% on the 2 occasions. For patients who met the internal consistency criterion for intensity words there was very high test-retest stability for the group scale values of the intensity words. There was no evidence that the level of psychological distress was associated with ability to scale unpleasantness words. Intelligence was positively related to the ability to scale intensity descriptors.