Do people choose pain over boredom?
People are unhappy in their own company and some prefer painful experiences to their own thoughts, a new study claims.
In one test, nearly half the subjects gave themselves mild electric shocks during 15 minutes of quiet time.
The findings, which came from shutting people away with no distractions and then quizzing them, have attracted criticism from some other researchers.
The contentious paper, in the journal Science, argues we are not very good at enjoyable, recreational thought.
Prof Timothy Wilson, who led the research at the University of Virginia, US, said: "Our study participants consistently demonstrated that they would rather have something to do than to have nothing other than their thoughts for even a fairly brief period of time."
This might not be a surprise if you are easily bored, or have ever picked at a painful scab in a quiet moment.
In fact, other researchers in the field have said the findings are overstated.
But the authors write that the question of whether people enjoy "just thinking" has been overlooked in psychological research.
Their work began with several trials involving university students, who were shut in a small room with blank walls and asked to sit at a table "entertaining themselves with their own thoughts".
After six, 12 or 15 minutes, they were asked whether the time was enjoyable and whether it was difficult to concentrate. On average, their answers were near the middle of a nine-point scale or worse.
To show that this was not a problem arising from the poky laboratory room, or a character flaw unique to flighty students, other experiments required a wider pool of volunteers, aged up to 77, to complete a similar test at home, sitting at a computer. Unpoliced in their own homes, many of them "cheated" by checking their phones or listening to music.
A control group was asked to find an external distraction, alone, like watching TV or browsing the internet, and they had a much better time than those left to try to daydream.
Finally, Prof Wilson's team did the electric shock experiment to try to find out if quiet, solo thinking was unpleasant enough that people would actually prefer something nasty to happen. Sure enough, 18 of 42 people, more of them men than women, chose to give themselves at least one mild shock on the ankle when left alone for 15 minutes.
"It was kind of like a severe static shock, it was not a huge jolt, but it was a little painful," Prof Wilson told the BBC's Naked Scientists programme. "They seem to want to shock themselves out of boredom, so to speak."
These were all people who had experienced the same shock already and declared that, if given $5, they would part with some of it in order not to be zapped again. People who didn't think they'd pay to avoid the shock were excluded - as was one man who pushed the button 190 times.
"I'm not sure what was up with him," Prof Wilson said.
Some UK researchers have questioned aspects of the study, including the level of shock delivered, which was higher for men than women (based on early results in which women rated shocks as more painful) but was not varied between individuals. They point to the fact that individual pain thresholds vary widely, and that hypothetical payments can exaggerate people's answers.
Sense of purpose
Prof Wilson says he isn't declaring humans incapable of contemplation. "I don't want to exaggerate this. I do think that all of us, in our daily lives, do find our minds wandering to pleasant topics or thinking about something we're looking forward to. I think what's hard... is doing this on the spot."
Prof Ivo Vlaev, a behavioural psychologist at Warwick University and Imperial College, London, thinks the findings are "very interesting" but the electric shocks could be over-emphasised.
"The bottom line is that they felt miserable," he told BBC News. "Research has shown that happiness is not only about experiencing pleasure. You need a sense of meaning and purpose - which you lack in these conditions. And when you have a task to do, you do have that sense - even if it's a simple task."
Dr Chris Chambers, a senior research fellow at Cardiff University's School of Psychology, was less impressed with the results.
"This is essentially a study showing that people don't like to be bored," he told BBC News. "How this could take up 11 experiments in a major scientific journal is a little mystifying.
"The most interesting aspect to the study is that their research subjects preferred to give themselves electric shocks rather than experience boredom. Perhaps the subjects simply did it to stay awake, and having now read the author's paper from beginning to end I can understand their plight."