Depending on whether we’re considering what constitutes a good actor from the viewpoint of the audience or the performer themselves, we may arrive at a different conclusion. The audience frequently considers plausibility and the actor’s ability to affect them. However, these are incredibly individualised and dependent on the person’s experience, which is influenced by things like the culture and period of their upbringing. What was believed to be true in one nation in the 1950s may not be believed to be true in another nation now. A competent actor is created by paying close attention to the action in the scene, expressing a wide range of emotions subtly and effectively with the eyes, body, and voice, researching and analysing the script to make intriguing decisions that match the role. Depending on the audience and circumstance, the level of nuance needed to express those feelings can vary. You may have observed, for instance, that performers behave differently in comedy aimed at children vs serious films intended for adults. If done in the latter, the former can be viewed as being excessive. Here are two sequences from films when Robin Williams explains to a younger person that he understands the world better than they do. You can see Robin Williams performing in a particularly dramatic manner in the 1995 children’s film Jumanji (especially as soon as the music begins to play at 0:38), which fits the situation perfectly.
