Perceptive free sorting and verbalization tasks with naive subjects:: an alternative to descriptive mappings

The purpose of this study is to compare a free sorting task based on similarities to a descriptive analysis, both applied to the visual description of plastic pieces. On the one hand, 150 consumers sort 26 pieces varying along 3 factors: opacifying agent, coloring agent, and grain type. Multidimensional scaling allows the perceptive dimensions to be retrieved from the similarities between the plastic pieces. A sensory interpretation of these dimensions is made possible by the consumers' verbal descriptions of their own groups. The proximity of the subjects' sorting results reveals the homogeneity of their perception of the products. On the other hand, 12 trained panelists generate and rate 8 visual attributes to describe a representative 8-piece subset of the 26 original samples, reduced to suit the descriptive analysis constraints. Eventually, both methods lead to the same conclusions in terms of piece configuration, associated perceptive interpretation and perception -process parameter relations. (C) 2004 Elsevier Ltd. All rights reserved.