Eighty per cent of adults in the US and the UK are moderate users of the psychoactive drug, caffeine.
Of all the effects it has on our minds—enhanced attention, vigilance and cognition—perhaps least known is its tendency to make us more susceptible to persuasion.
This was demonstrated in a study by Pearl Martin and colleagues at the University of Queensland in Australia (Martin et al., 2005). In their experiment they tried to convince participants to change their minds about the controversial issue of voluntary euthanasia.
Participants were told that some in the university agreed that people should be allowed to end their own lives under certain circumstances, while others did not. In fact participants were chosen because they agreed that voluntary euthanasia should be legal and the experimenters wanted to see if they could be persuaded otherwise.
Before the attempt to change their minds, half the participants were given moderate doses of caffeine, while the other half took a placebo. Both groups were double-blinded so that neither the researchers nor the participants knew who had taken what. Then they were given six stories to read which argued against euthanasia.
When asked afterwards for their attitude to voluntary euthanasia, those who had drunk caffeine were more influenced by the persuasive message than those who’d had the placebo.
On top of this, participants were asked about their attitude towards abortion which, the experimenters guessed, would be indirectly influenced, since someone who disapproves of euthanasia is also likely to disapprove of abortion. And this is exactly what they found. The persuasive message had spread to a related idea and the effect was strongest amongst those who had consumed caffeine.
But why? What is it about caffeine that opens us up to persuasion?
The reason that a lot of persuasive messages pass us by is simply that we’re often not paying much attention to them; our minds easily wander and we prefer not to think too hard unless it’s unavoidable. By increasing our arousal, though, caffeine makes us process incoming messages more thoroughly, potentially leading to increased persuasion.
So watch out, all that coffee isn’t just making you twitchy, it’s also making you more susceptible to influence, even if only by enhancing your attention.
About the author
Psychologist, Jeremy Dean, PhD is the founder and author of PsyBlog. He holds a doctorate in psychology from University College London and two other advanced degrees in psychology.
He has been writing about scientific research on PsyBlog since 2004. He is also the author of the book “Making Habits, Breaking Habits” (Da Capo, 2003) and several ebooks:
- Accept Yourself: How to feel a profound sense of warmth and self-compassion
- The Anxiety Plan: 42 Strategies For Worry, Phobias, OCD and Panic
- Spark: 17 Steps That Will Boost Your Motivation For Anything
- Activate: How To Find Joy Again By Changing What You Do
Image credit: illuminaut
Psychology of Persuasion
→ This post is part of a series on persuasion techniques:
- How to Influence People
- The Persuasive Power of Swearing
- Loudest Voice = Majority Opinion
- Don’t Take No For An Answer
- The Influence of Fleeting Attraction
- Caffeine Makes Us Easier to Persuade
- Persuasion: The Right-Ear Advantage
- Balanced Arguments Are More Persuasive
- The Battle Between Thoughts and Emotions in Persuasion
- Are Fast Talkers More Persuasive?
- Persuasion: The Sleeper Effect
- Communicating Persuasively: Email or Face-to-Face?
- The Influence of Positive Framing
- The Illusion of Truth
- 9 Propaganda Techniques in Michael Moore’s Fahrenheit 9/11
- Persuasion: The Third-Person Effect
- 20 Simple Steps to the Perfect Persuasive Message
- Why Stories Sell: Transportation Leads to Persuasion
- How To Encourage People To Change Their Own Minds
- When Does Reverse Psychology Work?
- The One (Really Easy) Persuasion Technique Everyone Should Know
- The Single Most Effective Method for Influencing People Fast
- 9 Ways The Mind Resists Persuasion and How To Sustain or Overcome Them
- How To Make Persuasive Eye Contact