A young librarian has been exceedingly shy and fearful of people since childhood. She longs to make friends, but even casual social interactions cause her a great deal of shame and anxiety She has never been at a party, and she has requested to work in the least active section of her library, even though this means lower pay She cannot look at her rare customers without blushing, and she is convinced that they see her as incompetent and clumsy. Which anxiety disorder is most likely to be confused with this personality disorder?