Innovation relies on the obscure.

McCaffrey suggests that a "generic-parts technique" enhances creative problem solving. He uses a toy insight problem - the two rings problem - as an example. The participant has to fasten together two weighty steel rings using only a long candle, a match, and a 2-in. cube of steel. Melted wax is not strong enough to bond the rings, so the solution relies on noticing that the wick is a string, which can be used to tie the rings together. Once people notice this, they easily devise a way to extricate the wick from the wax (e.g., scrape away the wax on the edge of the cube). Here is his abstract, followed by his description of the generic-parts technique:

A recent analysis of real-world problems that led to historic inventions and insight problems that are used in psychology experiments suggests that during innovative problem solving, individuals discover at least one infrequently noticed or new (i.e., obscure) feature of the problem that can be used to reach a solution. This observation suggests that research uncovering aspects of the human semantic, perceptual, and motor systems that inhibit the noticing of obscure features would enable researchers to identify effective techniques to overcome those obstacles. As a critical step in this research program, this study showed that the generic-parts technique can help people unearth the types of obscure features that can be used to overcome functional fixedness, which is a classic inhibitor to problem solving. Subjects trained on this technique solved on average 67% more problems than a control group did. By devising techniques that facilitate the noticing of obscure features in order to overcome impediments to problem solving (e.g., design fixation), researchers can systematically create a tool kit of innovation-enhancing techniques.

Here is his description of the generic parts technique (GPT)

...two questions are continually asked as a person creates a parts diagram (see figure below). For each description a participant creates, he or she should ask, “Can this be decomposed further?” If so, the participant should break that part into its subparts and create another hierarchy level in the diagram. The second question to ask is “Does this description imply a use?” If so, the participant should create a more generic description based on material and shape. This procedure results in a tree, in which the description in each leaf (i.e., the bottom level of the tree’s hierarchy) does not imply a use and involves the material and shape of the part under consideration. Further, because the parts become smaller as the hierarchy levels progress, this process also calls attention to the size of each of the parts. In essence, the GPT helps subjects think beyond the common functions associated with an object and its parts.