Describe the Levels of Processing theory? What is its major weak point?

Describe the Levels of Processing theory? What is its major weak point?

Basically the Levels-of-Processing theory states that memory depends on how information is encoded or programmed into the mind. This theory proposes that deep processing is more effective than the shallow processing. There have been studies conducted which support this theory. For example Craik and Tulving showed that memory was better following deep processing than following shallow processing. The study looked pretty much something like this:
-They asked participants questions after showing them different words (example: Capital letters?)
-They then presented them with the word (example: Bird)
-Then particpants had to answer the question; Was the word in capital letters? (example: No/Yes)

Overall there were three categories of different types of questions that were asked: fill in blanks, rhyme or capital letters. The results of this experiment showed that deeper processing (fill-in-the-blanks question) is associated with better memory. An example of a fill-in-the-blanks question could be for example ''does the word fit into category...birds/etc?''

It has been stated and it is well known that the Levels of Processing Theory is quite influential. However there is a problem with it. The weak point is simply the circularity, mainly because it is hard to define depth of processing independently of memory. We cannot use memory performance to determine depth of processing and then turn around and use depth of processing to predict memory perfomane.