How do I show Pt correct answer while simultaneously timing them?

I'm having people answer 15 antonym questions (scale response; A-E). Afterwards, I want to let them go back through their answers, one by one (i.e., in a different questionnaire), and let them see their answer to each item. Meanwhile, on the same screen, I want to give them the option of changing their answer, if they want, and measure how long it takes them to decide whether to change their original answer.

I think this will take both MediaLab and DirectRT (for response times), but I'm unsure how to program MediaLab accordingly. Any help you can provide is much appreciated!

Thank you.

I think you could just use a regular fill in the blank. Then later on, present another fill in the blank and insert the prior item's variable name in the question wording. If the anagram is [I]tca[/I] and the first time they answer, the variable name is [I]q17[/I] and they said "act", then the next time you could use the question wording...

[I]Previously, when you saw the anagram "tca", you replied <q17>. Would you like to change your answer?[/I]

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PS. Sorry I misread and did this example with anagrams instead of antonyms but it's the same idea..