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You’ve probably heard the term ‘placebo’ or the ‘placebo effect’. You may have even wondered whether you experienced it yourself this morning when your coffee instantly woke you up, or last week when your headache disappeared after two paracetamols.
So, is this phenomenon real? If it is, how does the placebo effect work?
Dr Aron Hill, Senior Research Fellow in the School of Psychology and co-lead of the Brain Systems and Neurotherapeutics Lab at Deakin University, helps us understand how the placebo effect works.
Dr Hill defines the placebo effect as, ‘a phenomenon where someone experiences an improvement in symptoms from an intervention (such as a pill, drink, treatment or otherwise) that has no intrinsic pharmacological effects and contains no active ingredients.’
For example, in a medical context, placebos are often referred to as ‘sugar pills’ meaning they look like real pills, but they don’t contain any active medical ingredients.
So, now we know what the placebo effect is, how does it work within the brain and what factors influence it?
The placebo effect occurs when symptoms improve because of the person’s expectations and beliefs as well as the context in which the treatment is administered.
Medical research has shown that state of mind plays an integral role in development of disease. The mind can contribute to a physical disorder, but it can also contribute to its cure.
Simply being prescribed something by a trusted GP or swallowing a pill can leads the brain to believe there will be an improvement in symptoms, even if the patient is aware they have taken a placebo pill.
Dr Hill says even the setting we are in can contribute to the placebo effect, possibly as much as the ‘inert’ treatment itself.
So, the entire therapeutic experience — like the setting of a hospital or lab, the authority of a doctor, even the rituals that surround treatment — plays a part in the placebo effect, too.
While we’re in these settings, our brains become busy. The chemicals they release in these moments shape how we feel and respond to a placebo.
‘These elements can activate complex neurobiological mechanisms involving neurotransmitters such as endorphins, cannabinoids, and dopamine, and alter activity in brain regions linked to pain, emotion, and expectation, including the prefrontal cortex, anterior cingulate cortex, insula, and amygdala,’ he says.
Dr Hill explains the placebo effect may works by acting as a blocker to the areas of our brain that process and regulate how we feel.
‘Brain imaging studies show that placebo treatments can reduce activity in brain regions that process pain, while increasing activity in areas involved in emotional regulation. These effects highlight how a person’s beliefs, the meaning they attach to treatment, and the broader psychosocial context can lead to real, measurable changes in how they feel, even when the treatment itself lacks an active biological component,’ he explains.
According to Dr Hill, as far as we know, there is no single brain region that determines whether an experience is real or imagined. However, research indicates that several areas contribute to this evaluation.
‘The prefrontal and parietal cortices (located near the front and back of the brain, respectively), which support executive functions such as decision-making, attention, working memory, and planning, play an important role. The hippocampus, a curved, seahorse-shaped structure deep in the brain, which is critical for memory and contextual processing, also contributes.’
These regions then work together to assess if the ‘thing’ it’s encountering is ‘real’. This is how the placebo effect works in the brain.
‘Together, these regions compare incoming sensory information with stored memories, contextual cues, and expectations. This integration helps the brain assess whether an experience is likely to be externally generated or internally constructed such as imagined or remembered, guiding our sense of what is real,’ he explains.
Dr Hill says placebos are commonly used in clinical trials to test whether a new treatment works better than no treatment.
‘A classic example of how the placebo effect works might be a patient feeling better after taking an inert ‘sugar pill’, simply because they believe it will help,’ he explains.
‘For example, in a study of a new antidepressant, researchers might recruit 100 participants with depression. Half would receive the actual medication, while the other half would receive a placebo. Neither the participants nor the researchers would know who is receiving which and this is known as a “double-blind” study, helping to prevent bias,’ he says.
By comparing the outcomes of both groups, researchers can determine whether improvements are due to the medication itself or to psychological factors like expectation.
So, ‘placebo effect’ trials work by ensuring any observed benefits are truly due to the treatment being tested. These trials also can come in many different forms.
Dr Hill notes that the key to a successful placebo effect study is that the placebo closely resembles the active treatment in appearance and delivery, so that participants cannot tell the difference.
This ensures that any psychological effects are consistent across groups, allowing researchers to isolate the true effect of the active treatment.
‘Placebo pills are the most common placebo from a medical perspective, but for the placebo effect to work it doesn’t have to be a pill. It can also take the form of a saline injection, an inactive cream, or even sham (inactive) brain stimulation. In this case, the device may be placed on the scalp but deliver no real current, while still mimicking the look and feel of actual treatment,’ he says.
The placebo effect can also be observed in alternative medicine.
‘Many researchers believe that practices such as homeopathy, naturopathy, energy healing, or certain supplements may work less because of active ingredients and more because of the belief that they will help.’ says Dr Hill.
Dr Hill explains that regardless of whether we’re dealing with traditional or alternative medicine, the same phenomenon is at play; our minds and the environment we’re in can create a placebo effect.
‘In the case of alternative medicine, the calming ritual of a special tea, the reassuring touch of a practitioner, the time and attention devoted to the patient — all of these elements can shape how someone feels.
Together, they can activate the brain’s natural ability to ease symptoms like pain, anxiety, or fatigue,’ he explains.
But as Dr Hill notes, belief alone is not enough to confirm effectiveness. Without rigorous testing, many of these therapies remain unproven. Large, placebo-controlled clinical trials are essential to separate genuine biological effects from responses driven purely by expectation.
The placebo effect also works beyond medicine and can be observed in various everyday contexts.
In sport, for instance, athletes may attribute improved performance to specific routines or objects, such as wearing lucky clothing or maintaining a consistent pre-game ritual like visiting the same café.
In technology, perceptions of quality can also be influenced; viewers may report enhanced visual clarity when switching from HD to 4K resolution, even when the actual difference is negligible.
Similarly, mobile phone users often feel their device functions more effectively when more signal bars are displayed, despite this not always reflecting true network quality.
Branding offers another example, where identical products manufactured under different labels are perceived as differing in quality solely due to brand associations.
These instances demonstrate the wide-ranging influence of how the placebo effect works in shaping human perception and behaviour.
A morning coffee is something many of us look forward to when starting the day.
But is coffee a placebo? Dr Hill says the caffeine has ‘well-documented effects’ on the systems within our bodies that wake us up.
‘Coffee really can help us feel more awake. Its main active ingredient, caffeine, has well-documented effects on both the central nervous system, which includes the brain and spinal cord, and the sympathetic nervous system, which helps regulate functions like heart rate and energy levels.’
This is not the only effect caffeine has on the body.
‘Caffeine predominantly works by blocking receptors in the brain for a chemical called adenosine, which builds up over the course of the day and makes us feel tired. By blocking this chemical, caffeine reduces feelings of drowsiness and increases alertness,’ he explains.
In addition, caffeine can also have effects on the cardiovascular system, influencing physiological processes such as heart rate and blood pressure.
However, Dr Hill notes that recent research has also shown that there is a placebo element to how our brains react to the consumption of coffee.
‘Our expectations also matter; this is where the placebo effect works. For example, recent research using a double-blind placebo-controlled design has shown that ingestion of a placebo (decaffeinated coffee) in habitual coffee drinkers led to similar physiological and cognitive changes as drinking coffee containing caffeine.
Dr Hill adds, ’So, while caffeine has genuine and well-studied physiological effects, part of coffee’s impact also appears to come from the brain responding to what we expect it to do. The result is ultimately likely a combination of both biology and psychology,’ he believes.
Have you ever had an energy drink and felt an instant rush?
Dr Hill says that the high caffeine content in energy drinks is partly responsible for this jolt of energy.
Almost all energy drinks include caffeine, with some containing even more caffeine than a standard cup of coffee.
‘Many energy drinks and pre-workout supplements contain active ingredients that have real biological effects,’ he says.
Dr Hill also confirms caffeine is not the only stimulant included in these drinks.
‘Many also contain forms of sugar, which provides a quick source of energy, and some may also include additional compounds such as creatine, which has well-established effects on improving muscle performance,’ he says.
Dr Hill says that while we know such products can have energy-boosting effects on our bodies, the marketing of these products can exacerbate our expectations.
In other words, marketing can influence how well the placebo effect works for non-medical products, too.
‘Marketing can exaggerate expectations, and those expectations can also play an important role in shaping how we feel. If we believe a product will boost energy our energy or performance, that belief alone can make us feel more alert or motivated, even if the physiological effects are minimal.
So, while the ingredients may have genuine effects, part of what we experience may also come from the power of suggestion.
Dr Hill confirms with a resounding “yes” that the placebo effect is indeed real.
Even when nothing chemical is at work, the very act of receiving a treatment can spark powerful changes in the brain, shaping how we feel, what we expect, and how our body reacts.
The placebo effect highlights just how powerful the mind can be in shaping how we feel, think, and even perform.
