According to the research on spatial abilities described in your text, which of the following statements is true?
1) Women may receive higher scores if the instructions are related to traditionally 'female interests,' rather than traditionally 'male interests.'
2) A major portion of gender differences in spatial ability is traced to biologically based gender differences.
3) Although gender differences in spatial abilities are not consistent, gender differences in mental rotation have been consistently found throughout the current research.
4) The scores for mental rotation are distributed in a bell-shaped curve for both males and females.