Today we will… Consider how biological psychologists might explain sex & gender Examine chromosomal influences on sex/gender development Examine hormonal influences on sex/gender development psychlotron.org.uk

What do biological psychologists believe about the causes of experience and behaviour? How might a biological psychologist explain sex/gender differences between people? psychlotron.org.uk

Sex chromosomes Genetic blueprint for a person is organised into 23 pairs of chromosomes 22 pairs are both X shaped. the 23rd depends on whether the person is female or male XX – female XY - male psychlotron.org.uk

Sex chromosomes source: US National Library of Medicine psychlotron.org.uk

Chromosomes & hormones Everything develops as a female unless instructed otherwise The Y chromosome contains instructions for the body to produce androgens (male sex hormones) These cause the embryo to develop along the ‘male path’ psychlotron.org.uk

Development of ovaries, uterus and vagina Sexual development XX Development of ovaries, uterus and vagina psychlotron.org.uk

XY Sexual development Androgens Development of testes instead of ovaries Testosterone Development of penis; Changes to brain psychlotron.org.uk

Hormones What might be the result if… An XY foetus was insensitive to androgens? An XX foetus was exposed to unusually high levels of testosterone? psychlotron.org.uk

Atypical chomosomes Turner’s syndrome Klinefelter’s syndrome XO – only one X chromosome on 23rd pair Klinefelter’s syndrome XXY – additional X chromosome on 23rd pair psychlotron.org.uk

Atypical chromosomes Would people with these syndromes (Turner’s, Klinefelter’s) appear male or female? How might they be different from those with more typical chromosomes? psychlotron.org.uk

Turner’s syndrome psychlotron.org.uk

Photographs on next slide psychlotron.org.uk

Turner’s syndrome psychlotron.org.uk

Turner’s syndrome Physical differences (neck, stature) Underdeveloped ovaries, lack of menstruation at puberty Poor spatial and mathematical abilities Poor social adjustment psychlotron.org.uk

Klinefelter’s syndrome psychlotron.org.uk

Photographs on next slide psychlotron.org.uk

Klinefelter’s syndrome psychlotron.org.uk

Klinefelter’s syndrome Physical differences (stature, limbs) Underdeveloped genitalia Gynaecomastia in some cases Poor language abilities, learning difficulties ‘Shy and passive’ temperament psychlotron.org.uk