Polysemy

Polysemy means to derive a meaning.When we look at an image the meaning  it has will be different for each of us, and what the image induces will be based on our previous life experiences. Once  we focus on one meaning, many more sub meanings follow, allowing for many different interpretations of the original image.
Once text is added to the image, it reduces the wide range of meanings that could have otherwise been drawn from the image. Forcing you to make a connection between the text and the image.

To test this out I created a series of random shapes with a marker pen and then showed them to some friends to see what they could relate the shapes too.

Here was the most successful scribbling.

4 out of the 7 friends I asked likened the shape to some sort of flying object, and 2 of those 4 said a helicopter.
In order for me too get a higher percentage of people seeing it as a helicopter I added some 'swoosh'
marks commonly used in cartoons to suggest rapid movement.

The thinner swoosh marks I added worked a little, and a few more people thought it was a helicopter
I then  added some text to help lock in the meaning of the scribble: