Spatial–temporal Association Of Response Codes Effect: Evidence From Manual And Saccadic Responses

It is well known that cognitive representations of stimuli such as numerals (from 1 to 9), auditory pitch (from low to high), letters of the alphabet (from A to Z), and months of the year (from January to December) have spatial characteristics, and that these characteristics influence the speed of manual responses (e.g., Fischer, 2003). With respect to numerals, for example, smaller numbers (e.g., 1 and 2) facilitate left-side responses compared to right-side responses, whereas larger numbers (e.g., 8 and 9) favor right-side responses[which was called the spatial–numerical association of response codes (SNARC) effect] (Dehaene et al., 1993). This suggests the existence of a'mental number line,'i.e., a cognitive representation of the magnitude of numbers, and such a representation interacts with motor preparation in space. Walsh (2003) has argued that any spatially and action-coded magnitude will yield a relationship between magnitude and space. This raises the question whether there is a space–time association that is analogous to the already established space–number association.Ishihara, Keller, Rossetti & Prinz, (2008) investigated the spatial representation of'time'using speeded responses to the onset timing (early vs late) of a probe stimulus following periodic auditory clicks. Participants pressed one of the two response keys depending on whether the timing of a given probe was earlier or later than expected based on the preceding clicks. The results showed that left-side responses to early onset timing were faster than those to late onset timing, whereas right-side responses to late onsets were faster than those to early onsets when the response keys were aligned horizontally. These results suggest that time is represented from left to right along the horizontal axis in space. The existence of a'mental time line'in space and the spatial–temporal association of response codes (STEARC) effect are discussed.According to one model, The STEARC effect reflects a space-related representation of time magnitudes (mental time line) with a genuine left-to-right orientation. Alternatively, it may simply reflect an over learned motor association between time and manual responses, in which case it should be weaker or absent with effectors whose horizontal response component is less systematically associated with individual time perception. Four experiments involving comparisons of saccadic and manual classified judgment tasks clearly support the first view. Experiment 1a and Experiment 1b tested the STEARC effect using horizontally arrayed left/right responses, Experiment 2a and Experiment 2b used vertically arrayed bottom/top responses. We were interested in whether'future'vocabulary would be categorized in the lower portion and'past'in the upper portion of the vertical axis (as in the vertical STEARC). The result suggesting that our magnitude representation resembles a time map, rather than a time line.