Contest: What Are Mental Images?

Cognitive scientists often define "iconic representations" (or mental images) as those in which “parts of the representation correspond to the parts of the entities represented.” (This wording is taken from Susan Carey's book, The Study of Concepts.) Call this the Spatial Decomposition Principle.

Something like the Spatial Decomposition Principle is true of realistic pictures: every part of a (realistic) picture of your mother is a realistic picture of a part of your mother. (OK, OK: something of an idealization: just suck it up.)

But it is not true of mental images . . .

Or even if it happens to be, it need not be. Summon up a mental image of your mother kissing you good night when you were an infant. Call this image MY MUM. MY MUM, i.e. the image, is presumably some kind of brain activation pattern, perhaps a process. It's possible that every part of this brain activation pattern is an image of some part of your mother,in exactly the same sense as MY MUM.  But there is no reason to think that this is the way mental images work--even less reason for thinking that this is how they must work.

Still: intuitively something like this holds for mental images too. Intuitively, the discursive concept SQUARE does not decompose: the spatial parts of this concept, whatever those might be, do not represent parts of the concept SQUARE. But a mental image of a square does image parts of the square. This is the difference between iconic representations and other mental representations.

Challenge for readers: how should we rework the Spatial Decomposition Principle for mental images?

PRIZE for best attempt: photo and kudos on New APPS! (Destructive criticism is eligible for kudos, maybe photo too.)