Right, isn't that weird though! :-)
I don't know if it's weird; generalising a category from specific examples is saves memory space over remembering every individual teacup we've ever seen, so going the other way starting with a general concept of a teacup and only specifying as and when needed seems to make sense.
I obviously failed to communicate what I was saying.
If you give me a teacup and tell me to imagine I can see it, I have to know what it looks like before I can form that image.
This is all just a failure of communication because to me, part of the definition of having an image of something in your mind is that you know what it looks like.
Since knowing the colours and shapes are required to form an image, if you don't have those, you don't have an image.
Imagining a teacup is possible without imagining you can see a teacup.
I'm imagining a teacup - made of china, decorated in some way, capable of holding a few mouthfulls of ~75C thin liquid, smaller than a big mug, larger than a shot glass, with a handle sizes for the tip of one finger, delicate, ceremonial; concept space constrained to broadly teacup-ish area. But not a specific teacup unless it becomes important whether it's a plainer heavy duty cafe teacup or a grandma's Royal Jubilee promotional teacup.