Trait Ascription Bias
The tendency for people to view themselves as relatively variable in terms of personality, behavior and mood while viewing others as much more predictable in their personal traits across different situations.
Origin
The concept emerged from social psychology research on attribution theory. Pioneers Fritz Heider, Harold Kelley, and particularly Edward E. Jones and Richard E. Nisbett developed the foundational "actor–observer asymmetry" argument in the 1970s, showing people assign traits to others they wouldn't assign to themselves. A 1982 University of Bielefeld study by Kammer and colleagues demonstrated that subjects rated their own personality variability considerably higher than peers'. The bias has been actively researched for over three decades.