The Placebo Effect: A Definition

Jesus Ceja

Sentence Definition

The placebo effect is best defined as the phenomenon where an individual experiences

beneficial results from the expectation that they are consuming an active medicine/treatment,

even though the medicine/treatment is inert (inactive). This is a frequently observed phenomenon

in the field of psychological research and is something that is still being researched and

understood.

The Process

For the placebo effect to occur in an experiment, a series of conditions must be met.

There must be a control group, which is given the inert placebo. In contrast, there must be an

experimental group, which is given an active medication. All participants are to believe that they

are taking the same medication and that the results of the medication are to be collected after a

certain time. In instances of the placebo effect, the individuals in the control group report feeling

substantial improvement after treatment, despite not consuming an active medication. The

placebo effect is, thus, triggered by the individual’s belief in the treatment’s benefit, as well as

their expectation to feel better. This can occur in multiple different experimental situations,

including Drug Studies (where a drug’s effect is measured through self-report or physiological

assessment) and psychological studies (where an action or therapy’s effect is measured through

self-report and assessment methods.

The placebo effect is much more backed and recorded when occurring in studies

involving, as mentioned by Pinch (2016), ailments grounded in self-awareness, such as pain.

Through an increase in research on this topic, it is worth noting that there is evidence of a change

in neurobiological response from placebos in individuals (Pinch, 2016).

The first notable biological response relating to a placebo was through the following

study conducted by Levine, Gordon, and Fields (1978). This study involved intravenous

administration of a saline solution on individuals recovering from surgery. These subjects were

advised that the saline may be morphine, which resulted in a third of the patients reporting

reduced pain. When later adding an opioid antagonist known as naloxone, the patients’ pain

eventually returned. This notably displayed the physiological inhibiting of a placebo response,

which implies placebos play a physiological effect on subjects. Figure 1 visualizes the effect of

naloxone in the brain. In the previous study’s situation, the naloxone played a role in the brain

despite there being no opioid in the subject.

Figure 1

Naloxone in the Brain

Note. In Levine, Gordon, and Fields’ (1978) study, there was no “opioid” in subjects’ systems.

Image is courtesy of Hamameh, Newman, Cason, Ray, and Washington (2021)

observed that functional imaging of the brain yields a reduction in pain-related activity in many

of the regions of pain-circuitry in the brain, such as the thalamus (Wager and Atlas, 2015).

Rather than linking the biological effects to the inert substance administered, the authors instead

link these effects to the mind’s expectation and perception (Wager and Atlas, 2015). This study

serves as a more concrete analysis of the biological influence of a subject’s expectation from a

placebo.

Unlike Other Phenomena

There are many phenomena in psychology that draw comparison to the placebo effect,

despite having notable differences. An example of these phenomena is the Hawthorne effect.

This is defined as an increase in performance from individuals when they are conscious of the

fact that they are being observed by researchers (Perera, 2021). The Hawthorne effect is caused

by the subject’s performance increasing after realizing they are under observation, while the

placebo effect is much more unconscious and physiologically related. The placebo effect

involves increased physiological performance when expecting results from a treatment. While

the Hawthorne effect more heavily relies on a social situation to drive improvement, the placebo

effect’s improvement is driven by the mind’s expectation. This further illustrates the uniqueness

of this phenomenon.

Discovery and Origins

The discovery of the placebo effect dates back centuries. In The Imagination Effect: A

History of Placebo Power, Rosie Mestel (2017) discusses the first scientific demonstrations of

the placebo effect occurring as early as 1799. This same year, John Haygarth used metal rods
rumored to draw out illness to see if individuals with rheumatism, a disease marked by

inflammation and pain of the joints, would report improved pain. After this, 4 out of the 5

individuals reported improved pain symptoms (Mestel, 2017). As also mentioned by Mestel

(2017), The term placebo effect became clinical terminology after Henry K. Beecher coined it in

his studies on pain management. As noted by Hugh M. Smith (2006), Beecher used saline

solution on wounded soldiers after running out of morphine. Nearly half of the wounded reported

a reduction of pain after the administration of this inactive treatment (Smith, 2006). Beecher

from then on urged for placebos to be incorporated in future research, specifically in clinical

trials. One of Beecher’s notable points in his work, The Powerful Placebo, regards using a

“double-unknowns” approach to placebo experiments (Beecher, 1955). This approach is

otherwise known as a “double-blind” approach.

Reducing the Placebo Effect: The Double-Blind Procedure

The double-blind procedure is one of the central focuses of a clinical trial involving the

administration of placebos to ensure that a drug’s power and benefit are accurately measured. In

a double-blind experiment, neither the individuals nor the administrators (of the drug/placebo)

know who is receiving the drug or the placebo. The knowing lead researcher does not disclose

this information until after the experiment completes to avoid skewing results. The individuals’

unknowing of their assigned group makes it less likely that their expectation will influence their

results or behavior. Elimination of these extraneous variables allows for a more accurate

measurement of a given drug’s effect and benefit in a study. Figure 2 is an example of a standard

implementation of a double-blind procedure.

Figure 2
Example of Double-Blind Study

Note. The test and control groups of a double-blind procedure are to be created through random

assignment. Image is courtesy of the Trees of Life Journal (2005).

The Impact of the Placebo Effect

The placebo effect’s impact is critical to neuropsychology, as it is one of the first

scientifically researched and evident phenomena providing evidence of a link between the mind

and the physiological aspect of one’s body. As Lu (2015) mentions, placebo research has many

notable implications for future research. These implications include development of a

multidisciplinary approach using a combination of genetic analysis, brain imaging, and

psychological profiles to observe and analyze the differing effects of placebos on subjects (Lu,

2015).

This phenomenon is still very much open for study, further development, and eventual

future breakthrough. As research continues to uncover a stronger link between the psyche and

the physiological aspects of the human body, there may be an impact on the prevalence of drug

intervention in psychological and medical treatment. Newfound focus on the verbal positioning

when administering a drug (or placebo) will be critical to producing improved results.

References
Beecher, H. K. (1955). The powerful placebo. Journal of the American Medical

Association, 159(17), 1602. https://doi.org/10.1001/jama.1955.02960340022006. 

Common experimental designs. Trees for Life Journal - Common Experimental Designs. (2005).

Retrieved September 22, 2021, from https://www.tfljournal.org/staticpages/index.php?

page=Common-Experimental-Designs. 

Hamameh, N., Newman, B., Cason, R., Ray, B., & Washington, A. (2021). Expanding naloxone

distribution in county jails. Center for Behavioral Health and Justice. Retrieved September

22, 2021, from https://behaviorhealthjustice.wayne.edu/naloxone-toolkit. 

Levine, J. D., Gordon, N. C., & Fields, H. L. (1978). The mechanism of placebo analgesia. The

Lancet, 312(8091), 654–657. https://doi.org/10.1016/s0140-6736(78)92762-9.

Lu, S. (2015). Great expectations. Monitor on Psychology. Retrieved September 22, 2021, from

https://www.apa.org/monitor/2015/04/cover-placebos.

Mestel, R. (2017). The imagination effect: A history of placebo power. Knowable Magazine |

Annual Reviews. Retrieved September 22, 2021, from

https://knowablemagazine.org/article/mind/2017/imagination-effect-history-placebo-

power. 

Perera, A. (2021). What is the Hawthorne effect? Simply Psychology. Retrieved September 22,

2021, from https://www.simplypsychology.org/hawthorne-effect.html. 

News. Retrieved September 28, 2021, from https://sitn.hms.harvard.edu/flash/2016/just-

sugar-pill-placebo-effect-real/.

Smith, H. M. (2006). Henry Knowles Beecher. Encyclopedia Britannica. Retrieved September

22, 2021, from https://www.britannica.com/biography/Henry-Knowles-Beecher. 

Wager, T. D., & Atlas, L. Y. (2015). The neuroscience of placebo effects: Connecting context,

learning and health. Nature reviews. Neuroscience. Retrieved September 28, 2021, from

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6013051/.