“studies of oxytocin, … the effect of nasal squirts of the hormone on trust are not reliably different from zero.
“Our initial enthusiasm for the [intranasal oxytocin] findings has slowly faded away over the years and the studies have turned us from ‘believers’ into ‘skeptics’,” the researchers write.
Nave suspects that it all comes down to probability, and has suggested that experiments like these are statistically equivalent to rolling a 20-sided die. Every time someone tests whether oxytocin works under certain conditions, they have a one in 20 chance of a positive result.
“If enough studies are carried out, every hypothesis will eventually be supported by some reports of experimental ‘evidence’,” Nave writes. When enough statistical tests are conducted independently, it is practically guaranteed that at some point, a desired result will appear.
There are now questions over whether it is even possible for nasally delivered oxytocin to cross the blood-brain barrier. If not, then it’s unlikely that a squirt can have any powerful effect on behaviour.