Jurors Believe in "Total Justice"
Neil Feigenson has written an outstanding book about how juror psychology and biases affect their judgments in personal injury lawsuits.
Legal Blame: How Jurors Think and Talk about Accidents.
Jurors are more concerned with making things "come out right" than with strictly following the relevant legal rules.
The narrative of a lawsuit is typically understood within the schemas and scripts of detective melodramas. Jurors want to perceive themselves as distinguishing and separating the good guys from the bad guys, and cast themselves as the hero righting the wrongs of injustice.
Intentionally or not, jurors often "nullify" the letter the law in favor of the spirit of what they believe to be the "morally" justified outcome.
Perhaps a better way to put it is that jurors try to follow the relevant law but are guided by a "total justice imperative" as they do so. "Total justice" impacts what jurors think and feel about the verdict they impose.
Research has indicated that jurors have a predilection for re-interpreting or disregarding the judge's instructions to ignore inadmissible evidence.
If jurors believe that the evidence has been ruled inadmissible because it is unreliable, then they are capable of not considering it.
However, if jurors believe that the evidence adds to their knowledge of the case before them, they are inclined to use it.