More is up... and right: Random number generation along two axes

Research on the mental representation of numbers has focused on a horizontally aligned mental number line, but more and more findings have begun to implicate a vertical orientation as well. We investigate the relationship between these two orientations when people generate random numbers. In the horizontal condition, people generated larger numbers when they looked right as opposed to left. In the vertical condition, people generated larger numbers when they looked up as opposed to down. We present two main results based on analyses that compare the two spatial orientations. First, we show that the vertical effect was stronger than the horizontal one. Second, we show a weak correlation between the vertical and the horizontal effect, potentially suggesting a shared underlying mechanism.