  This position paper explores the benefits, drawbacks, and ethical
considerations of incorporating synthetic personae in HCI research,
particularly focusing on the customization challenges beyond the limitations of
current Large Language Models (LLMs). These perspectives are derived from the
initial results of a sub-study employing vignettes to showcase the existence of
bias within black-box LLMs and explore methods for manipulating them. The study
aims to establish a foundation for understanding the challenges associated with
these models, emphasizing the necessity of thorough testing before utilizing
them to create synthetic personae for HCI research.
