These problems will only get worse as psychologists come to grips with oxytocin's subtler effects. As I've reported before, the hormone is highly contextual in its influence. It can trigger positive behavior in some settings, but negative ones like distrust, favoritism, envy, and schadenfreude in others. Biologically, this makes sense. Experimentally, it's a pain in the ass.
If scientists blindly run experiments, by complete chance, they'll find some condition in which oxytocin seems to be doing something—perhaps only in men, or in anxious people, or in anxious men. This is the sharpshooter fallacy, named after an imaginary Texan gunman who fires many rounds at the side of a barn and then paints a target around the biggest cluster of holes.
The best way to avoid this fallacy, says McCullough, is to start off with a strong theory—a solid idea about what oxytocin does, and what kinds of effects you expect to see. Fortunately, that's exactly what people like Young are building. Rather than searching for cute, TED-friendly psychological effects, they're working on the hard neuroscience of oxytocin, and working out exactly what this hormone does in the brain.
Young's team is giving oxytocin to human volunteers who sit in a brain scanner, to see how the hormone influences the communication and coordination between different regions of the brain, including areas involved in social information and reward. They have also mapped the location of oxytocin receptors in the brains of monkeys, and are looking at how those receptors affect the animals' behavior.
Others have done landmark studies in mice. In 2013, Richard Tsien at New York University Langone Medical Center found that the hormone improves the clarity of signals in the brain, by reducing the background buzz of neurons and causing those that fire to do so more sharply. A month later, Robert Malenka from Stanford University found that oxytocin and serotonin interact in a part of the brain called the nucleus accumbens, and together make social information more rewarding.
Just this year, Robert Froemke from New York University showed that oxytocin tunes the brains of mother mice to the cries of their pups, by acting on regions involved in hearing. And way back in 2001, Young found something similar: Mice can't tell each other apart if they can't make their own oxytocin, but they regain that ability if you inject the hormone into a brain region called the amygdala.
All of these results support the growing idea that oxytocin makes animals pay more attention to social information in particular, like the call of a youngster or the smell of a stranger. Psychologists imagine a spotlight that shines upon these social cues and makes them more salient. But neuroscientists are defining that process in terms of regions of the brain, the activity of neurons, and the actions of hormones.