Do hints improve memorization when using spaced repetition? For example, I'm learning geography using the spaced repetition method. I have some program which asks me questions like, "In which country Melbourne is located?", and I have to recall the country (assuming I've studied the material and at least once seen Melbourne on the map). This program also gives me two possible hints when I can't recall the answer:


If I choose "obvious hint" it says "kangaroo", which for me is a straight giveaway for "Australia".
If I choose "vague hint" it says "hell". After thinking a while, I may come up with this: "There's the Devil in Hell. There's an animal called Tasmanian Devil, which lives on the island Tasmania, which is near the Australia."


The idea in both cases is to not show the answer right away when I can't recall it, but rather force me (more or less) to try recalling it once again, but now with some additional information.

Questions:


Do obvious hints help memorization at all? As you saw, the hint "Australia" is as good as just showing me the answer, but maybe it helps building association in my memory which helps recalling the answer later.
Do vague hints help more? I assume yes, since they trigger some associations in my memory, but I have no proofs.


Of course, the "obviousness" of a hint is very subjective, but the idea behind it should be clear: "obvious" hints are just one or two associations away from answers, while "vague" ones form longer association chains.

EDIT: There is a related question with an answer which mentions elaborative rehearsal and depth of processing, but I'm not sure if those processes are involved here, since hints are mostly related to an answer ("Kangaroos live in Australia"), not a question ("kangaroos" and "Melbourne" are not associated in my memories, neither do "hell" and "Melbourne").
Short answer: Based on my assessment of the literature, I would say that a vague hint leaves room for retrieval practice, and will therefore likely elicit a testing effect. An obvious hint does not, and will therefore likely help recognition, but not recall.

Background

Spaced repetition refers to the practice of combining two well-known memory effects, namely the spacing effect and the testing effect, typically implemented in some form of flash cards. 

Testing effect

The testing effect aspect of spaced repetition is highly relevant. It refers to the finding that retrieval practice leads to improved long-term recall (cf. recognition) ability for a practiced item compared to non-practiced items. 

Modern theories on the testing effect tend to take the view that the testing effect represents a complex, active process in the brain rather than simple association formation or Hebbian learning. A critical meta-analysis of the recent testing effect literature unsurprisingly found support for the testing effect's existence, as well as some support for effortful processing as a contributing factor (Eisenkraemer, Jaeger and Stein, 2013). They did not find support for semantic elaboration theories (i.e., new/re-weighted brain associations).

Additional support for the testing effect as an active process comes from the fact that associated non-practiced items may be actively inhibited by retrieval practice, a phenomenon known as retrieval-induced forgetting (Anderson, Bjork and Bjork, 1994). We currently do not know much more than that the testing effect happens when we engage in retrieval practice. I know researchers who are studying exactly this, but at this point, I'm unfortunately not comfortable with discussing their thoughts or unpublished work. 

Spacing effect

I'm mostly including this for completeness' sake. The spacing effect was discovered by Herman Ebbinghaus in the 1880's and is one of the oldest phenomena studied in psychology. It refers to the tendency for animals to retain items presented over a longer period relatively better than when presentation of the same items is massed over a single brief period. It doesn't have any relation to the use of hints in spaced repetition learning, at least not one that I can think of.

References


Anderson, M. C., Bjork, R. A., &amp; Bjork, E. L. (1994). Remembering can cause forgetting: retrieval dynamics in long-term memory. Journal of Experimental Psychology: Learning, Memory, and Cognition, 20(5), 1063.
Eisenkraemer, R. E., Jaeger, A., &amp; Stein, L. M. (2013). A Systematic Review of the Testing Effect in Learning. Paidéia (Ribeirão Preto), 23(56), 397-406.