The dimensionality of verbal descriptors in Tursky's pain perception profile.

In the first part of the study 20 subjects (11 headache, 9 normals) free-sorted descriptors from the intensity and affect scales of the Tursky pain perception profile (PPP) into groups on the basis of similar meaning. In part 2 they made similarity ratings of all pairs of words within the intensity and affect scales. In the third part of the study subjects completed a cross-modal matching task to scale the intensity and affect words. Data from the first 2 parts of the study were examined with multidimensional scaling (MDS) and hierarchical cluster analyses. Free-sorting the descriptors did not produce 2 groups corresponding to the intensity and affect descriptors described in the Tursky PPP. The descriptors were arranged in 6 groups described by subjects as reflecting increasing painfulness. An MDS analysis showed that the groups could be located in 2-dimensional space in which the dimensions of intensity and affective distress could be easily discerned. When the descriptors from the intensity and affect scales were rated within each scale, a second MDS analysis showed that, whereas the intensity descriptors could be fitted by a 1-dimensional representation, the affect descriptors required a 3-dimensional model. There was evidence that subjects with extensive pain experience placed greater weight on the second and third affective dimensions compared with relatively pain-free subjects.