Additionally, does this extend into the rest of your interactions with people? Do you confuse different people often? How well do you assign names to people? (would blonde, wavy hair, ~5'3", named "Alyssa" be distinct in your mind from the same traits, but named "Elizabeth"?)

Visualizing a family member, for instance: I personally have a similar experience to yours, Guy, and find that when tasked to form an image of a parent, for example, the person becomes a hodgepodge of significant traits at best and just hair at worst. My father, for example, is just a bushy mustache with short curly hair and my sister is a slightly open-mouthed smile. My mother is just an outline of hair... and it's the hair color she had ten years ago, but no longer.