I think that when there's 3, 50% of my attention is on the moving square, where 30% is on the spikes, and 20% is on the balancing thing. :o
When there's 4 I seem to have 10% attention on the ball, 20% on the spikes 30% on the moving square, and 40% on the flying triangle. :o
EDIT: High score: 94. :D