Recently, researchers started to investigate the causal nature of attentional bias for threat (AB) in the maintenance of anxiety disorders, by experimentally manipulating it. They found that training anxious individuals to attend to non-threat stimuli reduces AB, which, in turn, improves anxiety. This effect supports the hypothesis that AB can causally impact on the maintenance of anxiety. At a fundamental level, however, uncertainty still abounds regarding the nature of the processes that underlie AB and its plasticity. According to one approach, the maintenance of AB is the result of the activation of a valence evaluation system. According to another approach, AB involves an impaired recruitment of top-down control. The main goal of the present theoretical paper is to put these two approaches, one against the other. Specifically, the artide is structured around three major issues. First, we will debate the possibility that AB may also result from an impaired valence evaluation system. Then, we will discuss the hypothesis that the reduction of AB requires top-down executive control. Finally, we will explore the potential interactions between these two contrasting approaches in the onset and the maintenance of AB. We will also discuss the potential impact of these two approaches in the understanding of the other types of cognitive biases.