When Lori got an A on her music history paper, she concluded that she was indeed smart. The next week, however, when she failed her biology test, she blamed the professor's "confusing" questions for her poor result. Lori is using what barrier to accurate perception?

Self-serving bias

Explanation:

Self-serving bias: In psychology, the term "self-serving bias" is defined as a person's propensity or proclivity to "attribute" any of the positive situations or events to his or her self or character and therefore "attribute" any of the negative situations or events to some external factors.

In social psychology, self-serving bias is generally referred to as one of the types of cognitive bias.

In the question above, Lori is using "self-serving bias".