Scores are normalized in units of SDs. The vertical axis is V, the horizontal axis is M, and the length of the arrow reflects spatial ability: pointing to the right means above the group average, to the left means below average; note the arrow for business majors should be twice as long as indicated but there was not enough space on the diagram. The spatial score is obviously correlated with the M score.
Upper right = high V, high M (e.g., physical science)
Upper left = high V, lower M (e.g., humanities, social science)
Lower left = lower V, lower M (e.g., business, law)
Lower right = lower V, high M (e.g., math, engineering, CS)
Because of the selection criteria I wouldn't be surprised if the SDs are large in this population. Many of the SMPY qualifiers could have relatively average V scores and vice versa for SVPY. So the variation between the highest and lowest scores in each ability could be larger than in the general population.
