Gamma bias refers to a cognitive gender bias theory developed by Seager & Barry (2019).1
Gamma bias refers to the operation of two concurrent biases: alpha bias (exaggerating or magnifying gender differences) and beta bias (ignoring or minimizing gender differences). Gamma bias occurs when one gender difference is minimized while simultaneously another is magnified, resulting in a doubling of cognitive distortion.2
Seager & Barry state that gamma bias works by magnifying women’s issues and achievements and minimizing men’s issues and achievements. Alternatively, the dynamic is reversed and employed to minimize negative female traits and behaviors, while magnifying or exaggerating negative male traits or behaviors.
Theories on the purpose of gamma bias
Hypotheses regarding the growth of gamma bias and the disfavoring of males include evolutionary pressures for males to protect and provide for women which involves a reluctance to view men as vulnerable, or alternatively the sociological explanation of ‘ingroup’ and ‘outgroup’ bias which may have developed around men and women in the form of social conventions.1
A more detailed explanation is provided by gynocentrism theory3 which posits the genesis of gamma bias in medieval Europe where feudal class distinctions between lords and vassals were re-applied to men and women. The application of such class distinctions led C.S. Lewis to refer to it as “the feudalisation of love,” making the observation that this sociological development “has left no corner of our ethics, our imagination, or our daily life untouched.”
Lewis explains that European society drifted essentially from a social feudalism to a sexual feudalism, fostering a convention of male chivalry in service to elevated Ladies of aristocratic society — a convention that moved by degrees, over time, to be embraced by all classes of people. The psychological operations supporting the ‘feudalization of love’ are numerous and involve gamma bias, male gender blindness, and also misandry to name a few. The internal operations result in a gender empathy gap which reinforces the root medieval trope.
 Seager, M., Barry, J.A. (2019). Cognitive Distortion in Thinking About Gender Issues: Gamma Bias and the Gender Distortion Matrix. In: Barry, J., Kingerlee, R., Seager, M., Sullivan, L. (eds) The Palgrave Handbook of Male Psychology and Mental Health. Palgrave Macmillan
 John Barry & Martin Seager, Can we discuss gender issues rationally? Yes, if we can stop gamma bias
 Wright, Peter. “Gynocentrism As A Narcissistic Pathology.” New Male Studies 9, no. 1 (2020).