A common processing system for duration, order and spatial information: evidence from a time estimation task.

The aim of the present study was to verify whether duration, order and space representations share common mechanisms. A two-alternative time estimation paradigm was implemented in two experiments in which subjects had to judge whether the first or the second tone in a pair was shorter (or longer) and to respond by pressing a left or a right key. In Experiment 1, subjects were more accurate in conditions where the first tone was shorter or the second tone was longer, with no effects of spatial information. In Experiment 2, a modification of the paradigm allowed us to demonstrate the presence of a SNARC-like effect, as evidenced by the interaction between order and response key, and of a second-order interaction among duration, order and space. These findings seem consistent with the hypothesis that processing of these three mental categories is subserved by a common mechanism, representing duration and order information according to a spatially-defined magnitude system.