The short answer: Yes, with variables and conditional triggers.
Slightly longer answer: Create a variable to track which persona is being used. I suggest using a Text variable, so you can set its value as a meaningful name, such as "self," "Ralph" "Susan," etc. (or whatever names you've given them). The default value would be "self," since they make choices as themselves on the first pass.
Adjust the variable when they select another persona.
On the slides of the scenario, include triggers that show appropriate persona content based on the value of the variable. The easiest would probably be to put each persona on its own layer. So, for example, there'd be a trigger that shows layer "Ralph" with the condition that the variable = "Ralph." Another trigger would show layer "Susan" with the condition that the variable = "Susan."
