Implicit attitude tasks have become very popular in various areas of psychology. However, little is known about the cognitive processes they involve. To address this issue, we investigated the underlying processes of the Go/No-go Association Task (GNAT), a go/no-go variant of the well-known Implicit Association Test (IAT). More precisely, we tested two alternative multinomial processing tree (MPT) models of GNAT performance, the Trip Model and the generalized Quad Model. Both models assume that GNAT performance is influenced not only by automatic associations but also by response biases and a controlled discrimination process. However, the two models differ with respect to an additional overcoming bias process. In contrast to the Quad Model, the Trip Model assumes that overcoming bias does not play a major role in GNAT performance. Instead, the Trip Model emphasizes the role of response biases. We report three experiments that demonstrate the validity of the Trip Model for GNAT data. Copyright © 2010 John Wiley & Sons, Ltd.