B.1.1. Introduction

Orienting visual selective attention relies mainly on two factors (Egeth & Yantis, 1997; Michael, Sellal, Fernandez, Garcia, & Boucart, 2006; Müller & Rabbitt, 1989; Ruz & Lupiàñez, 2002): the salience of the items in the visual field, and the knowledge and expectations the participants have and use about the task (relevance). Both take part in orienting attention, although there is no consensus about the way these two processes interact.