Does size rescaling require central attention?

The goal of the present experiment was to determine if object size rescaling in the shape-matching task requires central resources. Two polygons were presented side by side as the second task in a psychological refractory period paradigm. The polygons could be the same as each other or mirror images of each other and the size ratio between the two polygons was varied. In the first task, subjects were required to make a speeded response to the pitch of a tone. The polygon task followed at varying SOAs and the subjects then made a speeded same/mirror image judgement on the polygons. The size ratio effect was additive with SOA indicating that size rescaling is capacity demanding and that it requires central attention.