 This can be achieved when the two symbols have the same total surface area, density and brightness as the three symbols.Further studies show this discrimination extends to 4 vs 8, 15 vs 30, 100 vs 200, 7 vs 14, and 8 vs 12 symbols, again controlling for non-numerical factors.Many studies have shown that when given a choice, shoaling fish prefer to join the larger of two shoals.