On October 15 2019, the Facebook page “Weird Facts” shared the following “fact meme,” which claimed that the combination of a lot of coffee and a lot of stress could cause symptoms of schizophrenia — presumably in people not already diagnosed with the condition:
Underneath a stock image of coffee beans, text read:
Consuming too much coffee while under high amounts of stress can cause you to experience schizophrenic-like symptoms.
Like the balance of content on the page, no additional information such as a link to an article or other corroborating content accompanied the post. Within a few days, the image racked up a five-figure share count, with sharers commenting things like:
I’m extremely stressed and hopped up on coffee right now. I don’t believe this at all and neither do I.
When the experiment was reported, it tended to involve specific phrasing. In June 2011, Fox News declared “Large Amounts of Coffee Cause Hallucinations, Study Finds.” Finding the apparent basis of the claim was fairly straightforward. Also in June 2011, ABC Australia published an article reporting:
A team at Melbourne’s La Trobe University were researching mechanisms between the onset of schizophrenia and stressful life situations. They were trying to discover what caused stressed individuals who did not have a diagnosis of schizophrenia to show symptoms of the disease.
Lead researcher Simon Crowe says a sample of 92 undergraduate students were played White Christmas by Bing Crosby before being played static white noise for several minutes. The students were then asked to press a buzzer to indicate when, if at all, they could hear White Christmas playing in the background of the white noise.
Lead researcher Simon Crowe says, however, White Christmas was never played during the white noise.
The outlet paraphrased Crowe as saying that subjects who were “both highly stressed and had a high intake of caffeine were three times more likely to report hearing the song.” A 2011 La Trobe University press release discussed the experiment:
Five coffees a day or more was found to be enough to increase the participant’s tendency to hallucinate says Professor Crowe.
‘High caffeine levels in association with high levels of stressful life events interacted to produce higher levels of ‘hallucination’ in non-clinical participants, indication that further caution needs to be exercised with the use of this overtly “safe” drug,’ he says.
The participants were assigned to either a high or a low stress condition and a high or a low caffeine condition on the basis of self-report. The participants were then asked to listen to white noise and to report each time they heard Bing Crosby’s rendition of “White Christmas” during the white noise.
The song was never played. The results indicated that the interaction of stress and caffeine had a significant effect on the reported frequency of hearing “White Christmas”. The participants with high levels of stress or consumed high levels of caffeine were more likely to hear the song.
An abstract for “The effect of caffeine and stress on auditory hallucinations in a non-clinical sample,” published in April 2011 in Personality and Individual Differences, stated:
Both the diathesis-stress model and the continuum theory of schizophrenia attempt to explain the mechanism by which stress may facilitate the expression of the symptoms of schizophrenia in non-clinical samples. Caffeine has also recently been reported to increase proneness to hallucinate. In this study, 92 non-clinical participants were assigned to either a high or a low stress condition and a high or a low caffeine condition on the basis of self-report. After they had been primed, the participants were asked to listen to white noise and to report each time they heard the song “White Christmas” during the white noise. The song was never played. The results indicated that the interaction of stress and caffeine had a significant effect on the reported frequency of hearing “White Christmas”. The results demonstrated that high caffeine levels in association with high levels of stressful life events interacted to produce higher levels of “hallucination” in non-clinical participants, indicating that further caution needs to be exercised with the use of this overtly “safe” drug.
We were unable to access the full text of the research, which involved 92 individuals who had “been primed” via a suggestion the song “White Christmas” was playing alongside white noise. However, the suggested song did not play — only the white noise. Incidentally, 1998 research indicated it appeared “patients with schizophrenia have high caffeine intakes,” for which the reasons are, it said, unclear.
Researchers also found that people with schizophrenia “do not develop anxiety at high doses of caffeine.” Separate 2013 research on hallucinations stated in its abstract that “it has been suggested that auditory hallucinations are an entity by themselves and not necessarily indicative of transition along the psychosis continuum,” i.e., hallucinations and psychosis do not necessarily go hand in hand. And in 2009, researchers using an emailed survey found that coffee drinkers might hallucinate more often.
In a new article, psychological scientists Maryanne Garry and Robert Michael of Victoria University of Wellington, along with Irving Kirsch of Harvard Medical School and Plymouth University, delve into the phenomenon of suggestion, exploring the intriguing relationship between suggestion, cognition, and behavior. The article is published in the June issue of Current Directions in Psychological Science, a journal of the Association for Psychological Science.
Over their research careers, Garry and Kirsch have both studied the effects of suggestion on cognition and behavior. Kirsch focused mostly on suggestion in clinical psychology, while Garry, whose work is supported by the Marsden Fund of New Zealand, was interested in the effects of suggestion on human memory. When the two got to talking, “we realized that the effects of suggestion are wider and often more surprising than many people might otherwise think,” says Garry.
Across many studies, research has shown that deliberate suggestion can influence how people perform on learning and memory tasks, which products they prefer, and how they respond to supplements and medicines, which accounts for the well-known placebo effect.
But what can explain the powerful and pervasive effect that suggestion has in our lives? The answer lies in our ‘response expectancies,’ or the ways in which we anticipate our responses in various situations. These expectancies set us up for automatic responses that actively influence how we get to the outcome we expect. Once we anticipate a specific outcome will occur, our subsequent thoughts and behaviors will actually help to bring that outcome to fruition.
The coffee experiment involved a sample of 92 participants, and subjects were specifically directed to “hear” a single song — “White Christmas.” The June 2012 article noted that the power of suggestion, research suggests, is not limited to direct suggestion, and that indirect pushes can be just as strong:
But it’s not just deliberate suggestion that influences our thoughts and behaviors — suggestions that are not deliberate can have the very same effects. As the authors point out, “simply observing people or otherwise making them feel special can be suggestive,” a phenomenon termed the Hawthorne effect. As a result, people might work harder, or stick to a task for longer. And this case is more worrying, says Garry, “because although we might then give credit to some new drug or treatment, we don’t realize that we are the ones who are actually wielding the influence.”
In January 2013, The Chronicle of Higher Education examined myriad findings involving inherent suggestion, overt suggestion, and known difficulties in replicating the results of social and behavioral research — with a mention of “headline-making” research:
At the same time, psychology has been beset with scandal and doubt. Formerly high-flying researchers like Diederik Stapel, Marc Hauser, and Dirk Smeesters saw their careers implode after allegations that they had cooked their results and managed to slip them past the supposedly watchful eyes of peer reviewers. Psychology isn’t the only field with fakers, but it has its share. Plus there’s the so-called file-drawer problem, that is, the tendency for researchers to publish their singular successes and ignore their multiple failures, making a fluke look like a breakthrough. Fairly or not, social psychologists are perceived to be less rigorous in their methods, generally not replicating their own or one another’s work, instead pressing on toward the next headline-making outcome.
Much of the criticism has been directed at priming. The definitions get dicey here because the term can refer to a range of phenomena, some of which are grounded in decades of solid evidence—like the “anchoring effect,” which happens, for instance, when a store lists a competitor’s inflated price next to its own to make you think you’re getting a bargain. That works. The studies that raise eyebrows are mostly in an area known as behavioral or goal priming, research that demonstrates how subliminal prompts can make you do all manner of crazy things. A warm mug makes you friendlier. The American flag makes you vote Republican. Fast-food logos make you impatient. A small group of skeptical psychologists—let’s call them the Replicators—have been trying to reproduce some of the most popular priming effects in their own labs … What have they found? Mostly that they can’t get those results. The studies don’t check out. Something is wrong.
One defense of researchers’ inability to replicate results in some priming research is that it involves confounding factors that make it difficult to replicate overall. However, dissenters say they haven’t found that to be the case:
One possible explanation for why these studies continually and bewilderingly fail to replicate is that they have hidden moderators, sensitive conditions that make them a challenge to pull off. Pashler argues that the studies never suggest that. He wrote in that same e-mail: “So from our reading of the literature, it is not clear why the results should be subtle or fragile.” … Pashler can’t quite disguise his disdain for such a defense. “That doesn’t make sense to me,” he says. “You published it. That must mean you think it is a repeatable piece of work. Why can’t we do it just the way you did it?”
Regarding priming and coffee, a 2019 study published in the journal Consciousness and Cognition found that “people responded the same with thoughts of coffee and by drinking coffee.” In that research, the mere suggestion of drinking coffee (without its actual consumption) led to physiological arousal similar to that of drinking coffee directly.
Research on recall and memory has also dovetailed significantly with the topic of suggestion. Researcher Elizabeth Loftus is well known for findings about the reliability of memory and experiments involving a suggestion about an event that never occurred. In one widely-referenced experiment, a quarter of participants reported recalling an event that never occurred:
In a ground-breaking experiment, Loftus and her student Jacqueline Pickrell gave participants short narratives, all supposedly provided by family members, describing childhood events, and asked them to recall the events. Unbeknownst to the participants, however, one of the narratives was entirely false. It told of the person, as child of 5 or 6, being lost in a shopping mall for an extended period of time before finally being rescued by an elderly person and reunited with his or her family. In the study, nearly 25% of the small sample of participants reported to be able to remember this event, even though it never actually occurred. Many people were able to provide embellishing details that were not supplied by the investigators. Loftus interpreted this to mean that the very act of imagining the events led to the creation of false memories.
In 1997, Loftus wrote of the experiments:
My students and I have now conducted more than 200 experiments involving over 20,000 individuals that document how exposure to misinformation induces memory distortion. In these studies, people “recalled” a conspicuous barn in a bucolic scene that contained no buildings at all, broken glass and tape recorders that were not in the scenes they viewed, a white instead of a blue vehicle in a crime scene, and Minnie Mouse when they actually saw Mickey Mouse. Taken together, these studies show that misinformation can change an individual’s recollection in predictable and sometimes very powerful ways.
In terms of a single suggestion, Loftus — who has also warned of the dangers of disinformation and propaganda in this context — said:
In one example, participants viewed a simulated automobile accident at an intersection with a stop sign. After the viewing, half the participants received a suggestion that the traffic sign was a yield sign. When asked later what traffic sign they remembered seeing at the intersection, those who had been given the suggestion tended to claim that they had seen a yield sign. Those who had not received the phony information were much more accurate in their recollection of the traffic sign.
… Although strong suggestion may not routinely occur in police questioning or therapy, suggestion in the form of an imagination exercise sometimes does. For instance, when trying to obtain a confession, law officers may ask a suspect to imagine having participated in a criminal act. Some mental health professionals encourage patients to imagine childhood events as a way of recovering supposedly hidden memories.
We were unable to find additional research into hallucinations induced by coffee or caffeine intake, although there is a lot of existing peer-reviewed research into recall and suggestion. As noted by the Los Angeles Times‘ more balanced coverage of the research in 2011, the underlying research “has some flaws — [the study] was small, it was published in an obscure journal, and it wasn’t well-controlled.”
The meme claimed that “consuming too much coffee while under high amounts of stress can cause you to experience schizophrenic-like symptoms,” based on research involving 92 subjects and the false claim they heard a song they did not. In contrast with the meme, the abstract of the research in question proposed that “high caffeine levels in association with high levels of stressful life events interacted to produce higher levels of ‘hallucination’ in non-clinical participants.” The research does exist, but it was not as definitive as the meme implied.