In order to explain the Payne effect, filler networking or more recently a Langmuir type polymer chain adsorption have been suggested. Both mechanisms are in opposition. A number of chemically very different fillers (carbon black, graphitized carbon black, silica and hydrophobated silica) have been used to vary filler agglomeration and polymer adsorption strength both in non-polar NR and polar NBR, Payne-type testing of all compounds including a relaxation study led to the conclusion that filler networking is the dominant Payne mechanism in the case of silicas, whereas polymer adsorption dominates in the case of carbon blacks.