Time flies like an arrow: space-time compatibility effects suggest the use of a mental timeline.

The concept of time is elusive to direct observation, yet it pervades almost every aspect of our daily lives. How is time represented, given that it cannot be perceived directly? Metaphoric mapping theory assumes that abstract concepts such as time are represented in terms of concrete, readily available dimensions. Consistent with this, many languages employ spatial metaphors to describe temporal relations. Here we investigate whether the time-is-space metaphor also affects visuospatial attention. In a first experiment, subjects categorized the names of actors in a manner compatible or incompatible with the orientation of a timeline. In two further experiments, subjects categorized or detected left- or right-side targets following prospective or retrospective time words. All three experiments show compatibility effects between the dimensions of space (left-right) and time (earlier-later) and indicate that the concept of time does indeed evoke spatial associations that facilitate responses to targets at spatially compatible locations.