The spatial representation of grammatical number

Research on numerical cognition suggests a strong link between mental representations of space and quantity. The SNARC effect (Spatial-Numerical Association of Response Codes effect) is characterized by the association of small quantities with left space and large quantities with right space. While the majority of research on the spatial representation of number has been on number words or Arabic numerals, this study investigates quantity representations that are involved in the processing of grammatical number. We found that German words that were inflected for singular had a relative left hand advantage, and conversely, plurals had a relative right-hand advantage. However, this pattern was only found in relatively late responses. Moreover, it appeared to interfere with the opposite pattern caused by the MARC effect (Markedness Association of Response Codes effect) leading to a relative right-hand advantage for singulars. This interference appeared to depend mainly on response latency with MARC effects being more pronounced in early responses and SNARC-like effects being more pronounced in late responses. This work sheds light on the interaction of different stimulus-to-response mappings operating on the same stimulus dimension – grammatical number. Moreover, it suggests that spatial numerical associations go beyond explicit numerical information, as in number words or Arabic numerals.