  Throughout the past decade, research in HCI has identified numerous instances
of dark patterns in digital interfaces. These efforts have led to a
well-fostered typology describing harmful strategies users struggle to
navigate. However, an in-depth understanding of the underlying mechanisms that
deceive, coerce, or manipulate users is missing. We explore the interplay
between cognitive biases and dark patterns to address this gap. To that end, we
conducted four focus groups with experts (N=15) in psychology and dark pattern
scholarship, inquiring how they conceptualise the relation between cognitive
biases and dark patterns. Based on our results, we constructed the
"Relationship Model of Cognitive Biases and Dark Patterns" which illustrates
how cognitive bias and deceptive design patterns relate and identifies
opportune moments for ethical reconsideration and user protection mechanisms.
Our insights contribute to the current discourse by emphasising ethical design
decisions and their implications in the field of HCI.
