I am doing a college research endeavor on shape perception. Am wanting to convey we likely have similar perceptions of shapes - numbers, letters, if we have normal seeing and vision.

For instance, take the number 7, I asked someone how they perceive it, which they replied with horizontal line across then diagonal line from right of horizontal, directly under left of horizontal. Which is the exact way I perceive it. Philosophers that say we can never measure qualia, say that an on target verbal description will never match because our horizontal experiences could differ.

So, my question is - What ways can I experiment to see if its likely people have normal perception of simple shapes? In some cases can accurate verbal descriptions suggest likleihood?