Another sample of respondents was asked to indicate, on a seven point scale, the strength of the association between two motives. This leads to assessing the strength of all possible links between motives. The results of this exercise are represented in an additive tree (Figure 2) in which the external nodes correspond to the motives (Sattath and Tversky 1977). The input into the tree is the degree to which respondents consider two motives to be associated. The distance between is the sum of the length of all horizontal arcs on the path linking them. This distance reflects the average strength of the association between two motives. The horizontal distance from the root, also called “height”, reflects the average distance from all other motives. It can be seen as a measure of a motive’s centrality within the respondents’ world of thought.