When research participants were asked to repeat a message coming in one ear and ignore a message coming in the other ear, what were the researchers attempting to demonstrate scientifically?

The researcher is trying to demonstrate a scientific experiment called Dichotic  Listening

Explanation:

Dichotic listening is the listening to different acoustic events presented to each ear simultaneously. Most commonly, the acoustic signals are speech, such as digits, words, consonant-vowels, or sentences.

This test is used to carry out behavoural test of Central auditory processing which help to determine which ear (left ear or right ear ) has the best advantage in listening.

answer; the answer to the first question is (king james ii was replaced by his daughter mary and her dutch husband william of orange;