Perceptual and motor congruency effects in time-space association.

It is well established that temporal events are represented on a spatially oriented mental time line from left to right. Depending on the task characteristics, the spatial representation of time may be linked to different types of dimensions, including manual response codes and physical space codes. The aim of the present study was to analyze whether manual response and physical space codes are independent of each other or whether they interact when both types of information are involved in the task. The participants performed a temporal estimation task with two lateralized response buttons in four experiments. In the first experiment, the target stimuli were presented on the left side, at the center, or on the right side of the space, whereas the reference stimuli were always presented centrally. The reverse situation was presented in the second experiment. In the third experiment, both stimuli were presented in opposite spatial positions (e.g., left-right), whereas in the last experiment, both stimuli were presented in the same spatial position (e.g., left-left). In all experiments, perceptual and motor congruency effects were found, but no modulation of the congruency effects was found when both the perceptual and motor components were congruent. The results indicated that physical, spatial, and manual response codes are independent from each other for time-space associations, even when both codes are involved in the task. These results are discussed in terms of the "intermediate-coding" account.