Ryan - a brilliant, enthusiastic young scientist - spent a two-year layover in my neuroscience laboratory between his undergraduate studies in Vancouver and graduate school on the East Coast.
On his last day in California, we sat over drinks, reflecting on his plans for the future.
I offered some parting advice and then asked the question I pose to everyone who graduates from my laboratory: "What could I have done better?"
He hesitated, then replied: "You're too nice."
This was startling.
"Nice" might count as faint praise, but is it really an insult?
I asked him to elaborate.
Empathetic distress motivates people to avoid causing suffering at all costs. Like the Hippocratic oath, it inspires us to do no harm. But it can also encourage comforting lies over difficult truths.
"Well," he said, noticeably uncomfortable, "You're so nice to everyone here that we don't really know what you think about anyone. Some people end up assuming the worst."
Later that night, I realised he was right, though I would use a different term. I was addicted to politeness.
Not everyone shares my addiction. In fact, our culture is in the middle of a politeness shortage.
Imagine a reader from five years ago leafing through today's newspapers. He would probably be shocked at the vulgarity of our national conversation.
Social media is overrun with bullying. CNN warns parents they might want to clear the room of small children before the president's remarks are broadcast.
For the past dozen years, I have studied empathy: people's ability to share and understand each other's feelings.
Empathy is a powerful, ancient engine for kindness.
If you flinch when someone else is shocked, you are more likely to step in and help him.
If you think deeply about the suffering of homeless people, you are more likely to support policies that protect them.
Empathy also comes in different flavours, including distress - an aversion to seeing others in pain - and concern - a desire to improve their well-being.
These pieces of empathy often split apart.
Imagine you have a friend about to launch an ill-advised business adventure or marry someone you know to be unfaithful.
Tell him the bad news and he will feel hurt, but he will also have information to make wiser choices.
Empathetic distress motivates people to avoid causing suffering at all costs. Like the Hippocratic oath, it inspires us to do no harm.
But it can also encourage comforting lies over difficult truths.
In one study, college students privately rated a peer's application to graduate school and were told that the writer had suffered a personal tragedy. They then had the chance to re-rate her essay, this time knowing she would see their evaluation.
Readers inflated their assessments for the writer's benefit, especially when they empathised with her.
Oncologists often avoid using the word "cancer" during diagnoses, replacing it with vague, sanitised language. This might make conversation easier, but can also leave patients in the dark.
A physician at a neonatal intensive care unit once told me about a family whose child would probably die in the coming weeks.
The medical team had never told them this bluntly. He said: "They're such nice people and you don't want to tell them such bad news."
This is polite, but not kind.
To truly care for people, we often must steer them into hard feelings.
Parents teach their kids to be wary around strangers. Therapists encourage phobia patients to confront things that terrify them.
This reflects a deeper concern for someone's long-term well-being.
Many of us are willing to make family and close friends uncomfortable in the service of helping them, but do not extend the same courtesy to colleagues or acquaintances.
They could often use it just as much.
By protecting my students' feelings too forcefully, I might have been stunting their growth.
I now realise my politeness stemmed from a shallow empathy.
I strove to guard others - and probably myself - from pain rather than to enrich us.
Ryan was kind enough not to be nice to me and I am trying to follow his lead. My question for this year: Instead of doing no harm, how can I do the most good?
• Jamil Zaki is an assistant professor in the Department of Psychology at Stanford University.