P revious research suggests that musical context affects the formation of similarity relations among motivic/thematic materials during listening, and that three contextual aspects, namely contrasts in surface features and the organization and development of the musical materials, shape the listening experience of complete works. We empirically investigate the effects of these three contextual aspects on the perceived similarity of motivic variations while listening to Boulez's Anthèmes . This piece exists in two versions: 1) solo violin, and 2) violin and electronics. They contain clear categories of motivic materials, whose recognition can be studied within the natural contexts of the two versions. In Experiment 1, participants freely classified motivic variations extracted from Anthèmes 1 representing different motivic categories. In Experiment 2, participants provided dissimilarity ratings for these variations. From these results, motivic models were selected for each category. In Experiment 3, musicians identified variations of the models while listening to either version of Anthèmes . The results indicate that musical contexts that are more contrasting on the surface, or more predictable in terms of motivic features and organization, facilitate the identification of motivic variations, whereas the overall formal development of the musical materials and their context over time disturbs the recognition of those variations.