the photocopier study: what the word because really does
A famous 1978 experiment at a university photocopier is often summed up as "just say because and people will comply". The real result was more interesting, and more useful. The empty reason worked only for a tiny favour. When the ask got bigger, people wanted an actual reason.
By Brightside English editorial team
Reviewed by a Brightside senior coach · · 5 min read
Partly, and only for small requests. In Ellen Langer's 1978 photocopier study, a meaningless reason ("because I have to make copies") worked as well as a real one when someone asked to copy five pages. For twenty pages it worked no better than no reason at all, while a real reason still helped. Later replications have been mixed. Give a real reason, especially for bigger asks.
The study
In 1978 Ellen Langer of Harvard University, with Arthur Blank and Benzion Chanowitz of the Graduate Center of the City University of New York, published "The mindlessness of ostensibly thoughtful action" in the Journal of Personality and Social Psychology. Their question was how often people really process what they hear, and how often they run on habit.
The first of three experiments took place at a copying machine in the CUNY Graduate Center library. The subjects were 120 adults, 68 men and 52 women, who came to use the machine. Just before each person started copying, an experimenter approached and asked to go first, using one of three versions of the request:
- Request only: "Excuse me, I have 5 pages. May I use the xerox machine?"
- Placebic reason: the same request, plus "because I have to make copies". This sounds like a reason but tells the listener nothing new. Everyone at a copier has to make copies.
- Real reason: the same request, plus "because I'm in a rush".
The size of the favour also varied. Sometimes the experimenter had 5 pages, sometimes 20. The researchers treated the favour as small when the subject had more pages than the experimenter, and large when the subject had fewer.
What it found
Here is the share of people who let the experimenter go first, from the paper's own table:
| Favour | No reason | "Because I have to make copies" | "Because I'm in a rush" |
|---|---|---|---|
| Small | 60% | 93% | 94% |
| Large | 24% | 24% | 42% |
For the small favour, the empty reason worked almost exactly as well as the real one. The authors read this as evidence of mindlessness: people responded to the shape of a request plus a reason, without checking whether the reason made sense.
For the large favour, the empty reason did nothing. Compliance was the same as with no reason at all. Only the real reason lifted it. When the cost of saying yes went up, people started to listen to what was actually said.
That second row is the part most retellings leave out.
Did it hold up?
The evidence since 1978 is mixed, and the cell sizes in the original were small: 15 or 16 people per group for the small favour, and 24 or 25 for the large one.
Popular retellings overstate it. The linguist Mark Liberman, writing on the University of Pennsylvania's Language Log in 2009, recalculated the figures and showed how even a respected summary had turned the result into something it was not. Across the whole study, requests with no reason were accepted quite often, and empty reasons were turned down about half the time. The real pattern, he noted, was that the empty reason behaved like a real one for small favours and like no reason for large ones.
A 1985 replication did not reproduce it. Valerie Folkes of UCLA ran four studies with the same copier setup, published in the Journal of Personality and Social Psychology. In two of them, compliance with no reason was already very high (93% and 83%), and giving a reason, empty or real, made no significant difference. She also found that people complied less when the reason was a poor one, such as "because I don't want to wait", than when it was a sympathetic one, such as feeling unwell. She argued that people were weighing the reasons, not ignoring them, while allowing that small favours may get only light thought.
Langer and colleagues replied in the same issue, saying nothing in those results changed their view. Their summary was simple: "People are sometimes mindful and sometimes not."
Later work is patchy. A 2018 trial in BMC Public Health by Heino and colleagues reviewed the follow-up literature and counted only one published direct replication, by Key, Edlund, Sagarin and Bizer in 2009, which they describe as reproducing the main effect but with over 20% of participants excluded. They also list conceptual replications reporting small positive effects of giving reasons. In their own trial, text reminders that explained why a task mattered did no better than short reminders.
So the fair verdict is mixed evidence. Reasons often help a request. The specific claim that an empty "because" works as well as a real reason holds, at best, for small and low-stakes favours, and even that rests on small samples.
How it gets misused
The study is often sold as a persuasion trick: add "because" to any sentence and watch people agree. Three problems with that:
- It ignores the big-favour result. For the larger request, the empty reason did nothing.
- It treats people as easy to fool. The follow-up work suggests people do weigh reasons, especially when something costs them.
- It invites hollow language. "We are changing the policy because of the new policy" may slip past once. It wears down trust over time.
What it means for you
Treat the photocopier study as a reminder, not a trick. A reason is a courtesy. It tells the other person you respect their time enough to explain.
For small asks, any honest reason smooths the way:
"Could I jump in before you? I'll be two minutes, because I have a call at four."
For bigger asks, the reason has to carry real weight. Make it specific, true and about something the other person can recognise:
"I'd like to move the client review to Thursday, because the new pricing from finance lands on Wednesday and I don't want to show them numbers that change a day later."
"Can you cover the weekend shift? My father has a hospital appointment on Saturday morning, and I'll take your Sunday next week in return."
Notice the shape: the ask, the word "because", a concrete reason, and, for a large favour, something offered back. A founder in Kochi asking a supplier to extend payment terms, a nurse in Doha asking to swap a shift, or a parent asking a teenager to give up a Saturday all follow the same pattern.
If you are speaking in a second language, a prepared "because" sentence is also a gift to yourself. It stops you from either over-explaining or asking with no context at all.
Sources
- Ellen Langer, Arthur Blank and Benzion Chanowitz, The Mindlessness of Ostensibly Thoughtful Action: The Role of "Placebic" Information in Interpersonal Interaction, Journal of Personality and Social Psychology, 36(6), 635 to 642, 1978. doi.org/10.1037/0022-3514.36.6.635
- Valerie S. Folkes, Mindlessness or Mindfulness: A Partial Replication and Extension of Langer, Blank, and Chanowitz, Journal of Personality and Social Psychology, 48(3), 600 to 604, 1985. doi.org/10.1037/0022-3514.48.3.600
- Ellen J. Langer, Benzion Chanowitz and Arthur Blank, Mindlessness-Mindfulness in Perspective: A Reply to Valerie Folkes, Journal of Personality and Social Psychology, 48(3), 605 to 607, 1985. doi.org/10.1037/0022-3514.48.3.605
- Mark Liberman, Generalization and truth, Language Log, University of Pennsylvania, 3 May 2009. languagelog.ldc.upenn.edu/nll/?p=1396
- Heino, Knittle, Haukkala, Vasankari and Hankonen, Simple and rationale-providing SMS reminders to promote accelerometer use: a within-trial randomised trial comparing persuasive messages, BMC Public Health, 18, 1352, 2018. pmc.ncbi.nlm.nih.gov/articles/PMC6286544/
Published by The Full Stop, the journal of Brightside English, in the The Experiments series. Every factual claim links to a source below; where accounts or findings are disputed, we say so. Sources checked on 26 Oct 2026. Reviewed by a Brightside senior coach. Corrections: see our editorial standard.