Final answer:
Lavinia and Carla's conviction that their own teams are superior exemplifies confirmation bias, which is supported by tribal thinking and can relate to the bandwagon fallacy.
Step-by-step explanation:
The beliefs held by Lavinia and Carla that their respective baseball teams are better simply because they are on them, best illustrate a cognitive bias known as confirmation bias. This type of cognitive bias occurs when individuals favor, seek out, or give more weight to information that confirms their pre-existing beliefs or hypotheses, while at the same time, ignoring or undervaluing evidence that contradicts their beliefs. A related phenomenon is the bandwagon fallacy, which is the tendency to do or believe something because many other people do the same. Both are examples of how our social identities and group affiliations can influence our perceptions and judgments, a concept also referred to as tribal thinking.