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Sure it can be done but you won't use effects to do it.
When you insert an object in Captivate, you have an option to enable or disable Visibility. You also have an option to name the object. So you would give the object a meaningful name and clear the Visibility option to "hide" it until needed.
Then you would create an Advanced Action that would hide some objects and show others.
After that, you would assign the Advanced Action to a Click Box or a Button or some other event.
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Want to warn if you are looking to see the effect . Is that the case? It may not be then as simple as showing the object to see the effect, because it depends also on the position of the playhead compared with the timeline of that object and the timing of the effect.
If you do not need an effect, just ignore this posting