Vertical spatial representation of numbers across two cultures

There is strong evidence that numbers are spatially represented. However, much of the research has been concerned with investigating number representation within the horizontal rather than the vertical dimension. It has been suggested that the organisation of the writing system, by rows or by columns, plays a pivotal role in shaping the mental number representation. We investigated the vertical number representation in British and Japanese participants, who were asked to randomly generate numbers after turning their heads up or down. Previous works showed that this method facilitated the access to the corresponding portions of the horizontal mental number representation. We found that neither group seemed to be affected by the up/ down head turns. These results are discussed in terms of cultural crossover, differences in the horizontal vs. vertical spatial and numerical representation, and sensitivity of the random number generation task.