Intelligence of an individual is directly related to her ability to comprehend what she sees, hears or reads.
If someone can correctly comprehend with very less input, then we can say that the person is more intelligent. However, comprehension with too less inputs may require the person to make too many assumptions.
So how much of 'assumptions' is too much?
This brings us to another parameter; the field of the topic.
In certain fields more the assumption, better is the comprehension. These are mostly creative areas.
In certain other fields, like science, assumptions have to be minimal and factual. In math, there must be no assumptions. Comprehension in math needs recollection of all the relationships between mathematical statements that are relevant to the given input.
So the inputs we take are added to the corresponding assumptions that we make in our head (in the
specific domain) to build our comprehension.
So how can we improve our comprehension ability?
A good understanding of the language used for taking inputs.
Knowing more things about the world.
Knowing how they are related to each other.
Knowing the quantitative nature of the connections between things.
First point helps us to interpret the input. Next 3 points help us make the right kind of assumptions about the topic. So, if we focus on improving the 4 points mentioned above, we can become more intelligent!