Abstract:

Previous studies have suggested that the mental representation of time might be tightly linked with physical space. The time-space interaction has been reported as the preference to associate the past with the left space and the future with the right space, which is called the spatial-temporal association of respond codes (STEARC) effect. The present study investigated three possible cognitive mechanisms underlying the STEARC effect. a) Whether the space-time association is a direct representation that associated temporal/spatial information with the left/right spatial responses. b) Whether the representation of space-time association is intermediated by a common spatial code, the intermediate common code leads corresponding spatial responses. c) Whether the representation of space-time association is intermediated by a distinct code which in turn conducts the spatial responses. All of the three possible space-time representation mechanisms have their own evidence from previous studies. The purpose of the present study is to explore the cognitive mechanisms of spatial-temporal representation. Three experiments were designed according to the dual-task paradigm (spatial task: press the left or right key to judge the meaning of temporal words or the spatial location of squares, font task: judge whether the words were italicized). Participants were asked to complete their judgment by manual (Exp.1 & 2) or saccadic (Exp.3) responses. In both experiment 1 and experiment 2, participants were assigned randomly into two groups——congruent group and incongruent group. In the congruent group, time-space association and response hand was congruent in spatial task and font task (left hand-past/left; right hand- future/right). While the time-space association and response hand was incongruent in the incongruent group (left hand-future/right; right hand- past/left). Experiment 1 investigated the influence of incongruent mappings in the font task on a concurrent STEARC task in which temporal information was completely irrelevant. Experiment 2 employed spatially incompatible mappings in a spatial compatibility task and investigated whether the location-to-response mappings also affected the spatial-temporal response associations. Experiment 3 investigated the specific associations that are responsible for the reversal of STEARC effect by means of dissociating the response modalities (saccadic and manual response) in the spatial and font task. Experiment 1 and experiment 2 found a reversal of STEARC effect in the incongruent group, which could only be interpreted in terms of the intermediate common representations of time and space association. And in experiment 3, participants under incongruent condition showed the STEARC effect, so that there was a specific association between the common representations of time and space. All of the results showed that the representation of the space-time association is intermediated by a common code, and there is a specific association between the common representation codes of time and space.

Key words: STEARC effect, intermediate common representation, reversed STEARC effect, specific association of effector