Functional fixedness

Biological Parallel

Crows use twigs as foraging tools but initially fail to see rocks as nutcrackers—objects have 'fixed' functions. Functional fixedness emerges from efficient categorization: once an object's use is learned, that association dominates. New Caledonian crows eventually innovate (rocks crack nuts), but initial fixedness reflects that most objects have primary functions, and exploring alternatives wastes time. Your difficulty seeing a book as a doorstop mirrors categorization systems optimized for quick object-function retrieval, not creative repurposing.