oxytocin helps the formation of memories for happy faces, according to new research due to be published in the August 1st issue of Biological Psychiatry. Oxytocin is a hormone that is known to facilitate labour and breastfeeding, but is also thought to be involved in maternal bonding, trust and sexual arousal.

Sigmund Freud suggested that traumatic events are forgotten because they are hidden from our conscious awareness, or repressed; Brown and Kulik (1977) found that highly emotional events, such as the assassination of John F. Kennedy are often vividly remembered (although this has been widely disputed); now, research published in the Journal of Consumer Research suggests that people tend to underestimate the intensity of the actual emotions if they are mixed, rather than happy or sad.