A method is proposed for measuring the visual conspicuity of an object in its background. Associated with each object is a conspicuity area, which is defined as the retinal area within which the object to be searched for is seen in a brief presentation. The size of this area can be used as a measure of visual conspicuity. Directing attention towards a certain location in the retinal field influences the shape of the retinal area concerned. Visibility and visual conspicuity turned out to be linked by directed attention. The experimental results are interpreted in terms of external and internal determiners of attention.