To be honest, I have no good idea. The obvious thing is to add a really long resting period before the subsequent note. Maybe engage the subject in a task of distraction while waiting.

But that is going to take a long time, so not ideal for a lab setting.

Absolute pitch is easier to recognize in life, because people who possess it can name a pitch completely out of the blue, and of pretty much anything, like a sneeze, door slam, not just piano tones.

So, there are three traits of AP --- which I gathered anecdotally, not scientifically --- that I think that might help to distinguish AP from a good RP.

1. AP works on anything with a stable, audible frequency. Memorizing the sound cannot provide that. (e.g. I cannot tell the frequency of a door slam, even though I can tune a violin without a tuner.) So, potentially, the test would use the type of sound they didn't train with.

2. AP also works really fast. As soon as they hear the sound, they know the pitch. No time for calculation. So, the subject should be asked to answer immediately.

3. People with AP doesn't seem to make mistakes at all.

All of these have led me to believe that AP is not a skill of adeptness. It's like they perceive sounds in a fundamentally different manner than I do, as if there is a separate mapping of frequency in their brain.

Again, this comment is based on my experience with people who have absolute pitch. I don't have a background in neuroscience to understand how AP works precisely, or to state definitively that the traits I described are universal among people with AP.

How are people identified as having AP?

Assuming they display AP-like abilities, the main signifiers of those who do not actually have AP are that

1. They consciously use relative pitch from a known reference tone when identifying another pitch "out of the blue", and

2. They have worked hard on acquiring relative pitch, which is something one consciously practises.

In abstract, it's impossible to design a test to take that into account because if your subjects have great pitch memory they can recall a reference pitch heard a long time ago and then use relative pitch to fill in the rest. This is indistinguishable from absolute pitch in almost every way except maybe speed.

In practise, spacing the tests out more than a day and asking subjects not to listen for other things between tests might help, without being foolproof.