From my research we didn't find any difference from student level.

The effect was the same for all levels. This rather surprised us, because we had an assumption that the visual representation instead of a verbal representation of a problem situation might benefit weaker learners more.

We, humans, are essentially a visual animal. So, it is no surprise that everybody benefits from visual representations.

My thoughts exactly. But we thought that weaker learners might be more hindered by the 20th century educational habit to transform each real situation in a verbose description of that situation.