Is the idea that a seemingly implausible, but demonstrable, event will evoke inquisitiveness about its underlying cause?

If so, how are you assessing relative perceived information gap (i.e., in this case, degree of distance from understanding how the observed sleight of hand trick was achieved)?

If I am following your line of inquiry, this will dovetail with causal reasoning. Age and experience (as well as education) effects are likely.

Or do you mean something like "acceptance of the seemingly impossible" is the construct of relevance here, which is likely to overlap more with tolerance for ambiguity and/or "magical thinking" as much as any form of curiosity.

Curiosity will always involve some form of inquiry oriented thinking, feeling, and (if sufficiently intense enough and able to be acted on) information-seeking behavior, rather than passive reception of an event (or even incurious, but engaged, observation, which is closer to situational interest in the absence of much inquiry, as, say, might be evoked from a fireworks display where it can be observed and enjoyed without any appreciable inquisitiveness about pyrotechnics, who set them off, etc).

In short: Is your hypothesis that prestidigitation will motivate some form of inquisitiveness and subsequent investigatory behavior based on a discrepancy (i.e., knowledge gap) between a seemingly implausible cause and effect relationship? If so, then the relative knowledge gap will probably correspond to the degree to which an onlooker metacognitively judges how well s/he understand how the trick was done and their confidence.

Can you elaborate...?

Yep, that's the gist of the "magic trick" experience: an implausible/impossible event that is nevertheless directly perceived. As the magic trick progresses, magicians include "convincers" that effectively "disprove" each rational solution that the spectator could thinks of. Leddington goes into more detail on the experience and the intense curiosity in his theoretical paper here:

http://onlinelibrary.wiley.com/doi/10.1111/jaac.12290/full

One idea I had for measuring the perceived information gap is the number of "convincers" during a magic trick. For example, take a simple coin vanish where the magician transfers a coin from his right to left hand, waves his hand, and the coin vanishes. The lowest level could only show that the coin is not in his left hand. One level up, would have the performance show left hand empty and the right hand in a natural position that people would assume is empty. One level further would have the performance show the front & back of both hands at the end of the trick.

(I hope I'm understanding your question correctly~ let me know if I'm not)

No, this would not be the same as magical thinking...although I do believe there could be some overlap between the two experiences.

The information seeking behaviour does seem to be an important part of the magic-trick experience, because in the context of a magic show, people expect to be tricked and hence try to figure it out.

Soo, yes, my hypothesis would be that watching magic tricks should increase this information seeking behavior. There is actually some evidence that this does occur, but is more likely when the magician's suggested explanation involves "magical" content (See Subbotsky, 2010 where he used a trick box, and manipulated the causal explanation provided to the spectator: http://onlinelibrary.wiley.com/doi/10.1348/000712609X470590/full )