An old postcard featuring a variation on the autosuggestion of Émile Coué (1857-1926) shows a small staircase of conviction. At first there is still uncertainty: I hope. Then it becomes I think. Finally, it says: I know. In just a few words, the card depicts how a thought changes shape, first as a wish, then as a possibility and finally as certainty.
Postcard featuring a variation on Émile Coué’s autosuggestion: first I hope, then I think and finally I know.
This is a fitting starting point for the history of the critical factor. Coué’s famous formula, “Every day, in every way, I am getting better and better,” was based on the idea that repetition shapes expectation. Popular wisdom tells us that hope keeps us alive. Coué gave that old idea a new form. By repeatedly putting a hopeful expectation into words, he believed it would gradually gain persuasive power.
But why does one suggestion work while another simply slides away? Why do some words reach a person, while others are rejected?
This question later became known in hypnosis practice as the critical factor: the faculty by which people assess new information against what they already believe, fear, expect and have experienced. In hypnosis training, it is often presented as a gatekeeper. That image is simple and useful, but the question behind it is far older than modern hypnosis.
It runs through philosophy, religious self-examination, medicine, hypnosis, psychotherapy and cognitive psychology. Yet it also lives outside the books of scholars. Popular wisdom has long known that “appearances can be deceiving,” that “the wish is father to the thought” and that “once bitten, twice shy.” Such expressions are not psychology in the scientific sense, but they are based on sharp observations of expectation, experience and conviction.
The history of the critical factor proves to be more than a prehistory of hypnosis. It shows how people in different periods tried to understand why a thought is accepted, doubted or rejected. Ultimately, it becomes a cultural history of human conviction.
Appearance and reality
A logical starting point is Plato (427-347 BCE), the Greek philosopher who reflected on knowledge, truth and education in the fourth century BCE. In his allegory of the cave, people are chained inside a cave. They see only shadows on the wall and take them for reality because they have never known anything else. Only the person who breaks free and goes outside discovers that what they saw was not reality itself, but merely its shadow.
Plato’s image touches on a problem that keeps returning: people do not perceive the world neutrally. They see it through habit, upbringing, expectation and experience. What is familiar seems naturally true. What is unfamiliar evokes resistance. Popular wisdom puts it more simply: not everything is what it seems.
Aristotle (384-322 BCE), Plato’s student and one of the founders of Western logic and psychology, shifted attention to the workings of the mind itself. He saw imagination not as a side issue, but as a necessary link between perception and thought. People remember, anticipate and reason through inner images. This is precisely where imagination can help, but also mislead. A vivid image can acquire almost the same power as a perceived event.
Here we already find an early precursor to a later question in hypnosis. Suggestion does not work because words possess magical power, but because words evoke images, expectations and feelings. A suggestion only works when it sets something in the imagination in motion.
Impression and assent
The Stoics (c. 300 BCE-200 CE), an ancient school of philosophy that devoted considerable attention to self-control and inner freedom, made this problem practical. They distinguished between the first impression that presents itself to us and the assent that may follow. A thought, fear or conviction may feel powerful, but that does not mean it is true or should be followed.
Between impression and conviction lies a small but decisive space. There, a person can investigate: is this correct? Should I go along with this? Is my first response reliable?
Doubt does not arise equally with every thought. People usually examine the unfamiliar more critically than the familiar. The convictions with which someone was raised can feel so self-evident that they are barely recognised as convictions at all. Doubt is therefore not only a sign of critical ability. The direction of doubt is also shaped by habit, upbringing and experience. What immediately arouses distrust in one person may be beyond discussion for another.
We cannot say that the Stoics discovered the critical factor, but they did formulate the problem for which that later concept provided a simple name: not everything that presents itself to the mind deserves admission into conviction. Popular wisdom puts it more briefly: look before you leap.
This idea later returned in religious forms of self-examination. Augustine (354-430), the early Christian philosopher who reflected on memory, desire and inner division, described the human being as someone who never fully sees through themselves. People do not judge with reason alone. Hope, fear, shame, love and memory all have a voice. In medieval monasteries and movements such as the Modern Devotion (1374-1500), this inner examination became a practice: not every impulse deserves trust, and not every inner voice points in the right direction.
These religious practices were not yet theories of hypnosis or suggestion, of course, but they did address a related problem: a thought that presents itself is not the same as a thought to which a person assents. Between impulse and acceptance lies a form of examination. That distinction would later become important again, in another language and within another practice.
Reason under suspicion
In the early modern period, attention shifted from conscience to reason. Francis Bacon (1561-1626), the English philosopher often regarded as a precursor of modern science, warned against the “idols” of thought: persistent distortions, or idola, that disrupt judgement. Some arise from human nature, others from language, upbringing, habit or reverence for authority. People do not see the world directly, but through patterns of expectation and prejudice, or as less learned people put it: “Everyone views the world through their own lens.”
René Descartes (1596-1650), the French philosopher of radical doubt, sought certainty by temporarily suspending everything that could be misleading. What may be admitted as true? What must be rejected as uncertain? This too was, in another way, an attempt to purify the mind’s faculty of judgement.
Other thinkers instead pointed to the forces that repeatedly interfere with reason. Nicolas Malebranche (1638-1715), a French philosopher and theologian, emphasised the power of imagination. People do not believe only because something has been logically proven. They may also believe because an image is vivid, a speaker projects authority or an idea is repeated often enough.
Imagination still works this way today. A short video of a crying mother, a threatening street or a successful influencer may carry more persuasive power than a page of statistics. Not because the evidence is stronger, but because the image settles into feeling more quickly.
Baruch Spinoza (1632-1677), the Dutch philosopher of reason and the affects, went further still: people believe they judge freely, but often do not know the causes of their judgement. Hope, fear, love and aversion colour reality before reason puts it into words. Here the history comes close to a modern insight: convictions are not merely conclusions drawn from arguments. They are interwoven with the body, emotion, memory, upbringing and environment.
An example is the way populist rhetoric, including rhetoric used by the PVV, links the safety of women in the street to migration. This is not only about concern regarding violence against women, but mainly about stereotyping victims and perpetrators. The women are portrayed as vulnerable “Dutch” victims who must be protected. The non-Western, Arab, North African or “dark” man becomes the self-evident threat. This creates a simple and emotionally powerful image: “our” women are no longer safe because “they” are here. The complexity of violence against women disappears into the background. Domestic violence, femicide, power relations, social control and perpetrators within all groups are replaced by one recognisable image of danger. In this way, critical judgement is partly pushed aside. The stereotype feels immediately true because it appeals to fear, protection, aversion and group loyalty before the facts have been examined.
Unlike a careful hypnotherapist, the populist does not ask for permission. The hypnotherapist works openly, with the client’s consent and with an agreed purpose. The populist politician does not. They do not announce that they intend to bypass critical judgement, but try to evade it through imagery, repetition, indignation and threat. The suggestion is not offered as a suggestion, but disguised as common sense: “everyone can see what is happening.” As a result, the listener does not feel manipulated, but awakened. That is what makes this form of influence so effective: it switches off distrust of the speaker by increasing distrust of a designated enemy.
Experience becomes expectation
John Locke (1632-1704), the English philosopher of empiricism, argued that the human mind does not enter the world with innate ideas, but is shaped by experience. These experiences do not remain separate from one another, but become connected. A child who repeatedly hears that dogs are dangerous may later feel tension before a dog has done anything at all. The body sometimes learns faster than reason.
David Hume (1711-1776), the Scottish philosopher who reflected on habit and cause and effect, went further. Much of what we call cause and effect, he argued, is based on repetition. Because we often see events occur together, we expect them to occur together again. Expectation then becomes a quiet force in our judgement. We think we are merely observing, but in reality we are constantly predicting.
American newspaper cartoon from around 1923 parodying Coué’s famous formula, “Day by day, in every way, I’m getting better and better.” The joke only works if the reader already knows Coué’s phrase. “Mangier and mangier” is a distortion of “better and better” and literally means becoming increasingly mangy.
Popular wisdom also recognised this phenomenon: “we learn through trial and error.” This is not laboratory psychology, but it does describe how experience becomes expectation. An old pain makes a new situation seem suspicious. A previous disappointment can block trust. A habit can be stronger than an argument.
The gaze of others
Finally, thinkers such as Montesquieu and Rousseau (1712-1778) brought the social environment more explicitly into view. Montesquieu examined how laws, customs and habits shape societies. Rousseau reflected on education, shame, inequality and the gaze of others. Both showed that people do not form their convictions in isolation. We live in communities that determine what is normal, suspicious, praiseworthy or shameful. “The walls have ears.”
Within families, villages, churches, schools and professional groups, a shared sense develops of what goes without saying. Those who deviate risk being laughed at, corrected or excluded. The judgement of others gradually becomes a voice inside one’s own mind.
This too matters for the history of suggestion. A suggestion never enters an empty space. It is received by someone who already lives within language, habits, authority and social expectations. That is why the same message may immediately resonate with one person and have no effect on another. Here too, the tone often makes the music.
Mesmer and the power of expectation
In the eighteenth century, Franz Anton Mesmer (1734-1815) believed that illness and recovery depended on an invisible fluid, which he called animal magnetism. No convincing evidence for the existence of this fluid was ever found. Mesmer is nevertheless historically important because the practice that developed around his theory made visible phenomena that his own theory could not explain satisfactorily.
His treatments were impressive events. Patients gathered around the famous baquet, a tub containing iron filings and iron rods. There was silence, tension, touch, expectation, authority and group feeling. People responded with warmth, trembling, crying, calm, pain relief or intense crises. Not everything was reliable, and much was probably shaped by expectation and context. That is precisely what makes Mesmer’s practice so interesting.
A French commission in 1784, whose members included Benjamin Franklin and Antoine Lavoisier, investigated Mesmer’s claims. It asked not only whether the fluid existed, but also what happened when people believed they were being magnetised. The researchers tried to separate the supposed magnetic effect from the participants’ expectations. People sometimes displayed physical or emotional responses when they believed they were being magnetised, even though the intended treatment was not taking place. Conversely, such responses sometimes failed to appear when they were magnetised without knowing it. The commission concluded that imagination and expectation played a more important role than the supposed fluid.
For Mesmer’s theory, this was devastating. For the history of psychology, it was fruitful. It showed that expectation itself can have physical and emotional effects. Not because thoughts override the laws of nature, but because meaning and expectation help shape human experience.
Here the later history of hypnosis, suggestion and placebo begins to become recognisable.
From magnetism to suggestion
After Mesmer, attention gradually shifted. The Marquis de Puységur (1751-1825) discovered that some people did not enter violent crises, but instead entered a calm, sleep-like state in which they could speak and respond. James Braid later rejected the magnetic explanation and focused on concentration, fatigue and mental focus. Hypnosis gradually became less of a mysterious force and more of a psychological phenomenon.
In Nancy, this development took a decisive turn. Ambroise-Auguste Liébeault and Hippolyte Bernheim (1840-1919) emphasised suggestion. Bernheim began to wonder whether hypnosis was really the most important phenomenon. Perhaps hypnosis did not explain the effect of suggestion. Perhaps suggestion explained much of hypnosis.
This was an important turning point. Suggestion became more ordinary and more important at the same time. It was no longer associated only with trance, sleep or magnetic force. It belonged to the way people respond to words, authority, expectation and trust.
The central question shifted accordingly. It was no longer only about the state a person was in, but about the conditions under which a message became plausible and effective. Suggestibility was not simply an openness to commands. It depended on meaning, expectation, the relationship with the practitioner and the extent to which a suggestion fitted what someone considered possible.
Bernheim observed that the same suggestion worked with one patient but not another. This difference did not depend on technique alone. Trust, previous experiences, the practitioner’s reputation, the atmosphere in the consulting room and the meaning the patient gave to the treatment all played a part.
Here lies a clear precursor to what would later be called the critical factor. A suggestion is not accepted automatically. It is weighed, sometimes consciously, but more often quietly and outside awareness, against everything a person already believes, fears, hopes and has experienced.
Elman and the hypnosis teaching model
In twentieth-century hypnosis practice, the concept of the critical factor is primarily associated with the hypnosis teaching of Dave Elman (1900-1967). He did not use it as a precisely defined scientific theory, but as a practical model that helped him quickly explain to doctors, dentists and therapists why a suggestion is sometimes accepted and sometimes rejected.
For this purpose, he needed clear images. The critical factor is one such image. Elman described how people compare new information with what they already know, believe and expect. When a suggestion conflicts too strongly with existing convictions, it is usually rejected. When it connects with what someone already experiences as possible, it can be admitted more easily.
His achievement did not lie in discovering a new organ of the mind. There is no censor somewhere in the brain stamping suggestions “admitted” or “refused.” Elman’s strength lay in pedagogical clarity. He gave a name to an old problem and made it useful in practice.
The enduring appeal of the concept lies in this simplicity. It names a recognisable experience: some words seem immediately plausible, others encounter resistance, and the same message can sound different when it is spoken by someone who inspires trust or carries authority. As a practical image, the critical factor is useful as long as it is not mistaken for a separate component of the mind.
When hypnotherapists say that hypnosis “bypasses” the critical factor, they are using a practical image. They mean that someone in hypnosis is less occupied with analysing, controlling and contradicting, and more engaged with experience, imagination and expectation. Suggestions can therefore sometimes be explored or experienced more easily.
This does not mean that a separate mental checkpoint is being passed. In hypnosis, a suggestion still reaches a person with memories, convictions, fears, desires and trust. Hypnosis does not switch judgement off. It changes the conditions under which something becomes plausible, imaginable or acceptable. That is precisely why the same suggestion works for one person but not another.
From gatekeeper to network
The gatekeeper image is actually too simple. Modern psychology does not see judgement as the work of one central agency. What we believe or reject emerges from the interaction of attention, memory, emotion, language, the body, social context and expectation.
Sometimes this judgement is conscious. We think, weigh arguments and draw a conclusion. Often, however, it proceeds more quickly and quietly. A face feels trustworthy or untrustworthy. A treatment evokes hope or suspicion. A political message sounds self-evident or threatening. A compliment is accepted or immediately dismissed.
Models of predictive processing in psychology fit this view. In these approaches, the brain is not presented as a passive receiver of information, but as a system that continuously forms expectations about what it is likely to perceive. New impressions are compared with those expectations. When expectation and experience diverge, the existing model may be adjusted, but the new impression may also be interpreted in a way that allows it to fit the familiar pattern.
This model is more refined than the image of a single gatekeeper. Yet it addresses the same fundamental problem: perception and conviction do not arise on empty ground. New information acquires meaning in relation to what is already expected, remembered and considered possible.
Popular culture and practical knowledge
Perhaps the most surprising aspect of this history is that many insights had long been present in popular culture. Not as theory, but as practical knowledge of human behaviour.
Popular wisdom summed up the core idea succinctly: “seeing is believing.” Such expressions are not psychology in the scientific sense, but they preserve observations about perception, experience and conviction.
Practices surrounding illness and recovery also show how strongly treatment can be connected with meaning. A visit to a holy spring, the laying on of hands by a healer, a prayer at a sickbed or the wearing of an amulet offers not only an action, but also a framework of expectation. The person who is ill knows what the ritual means, often knows the reputation of the place or practitioner, and is surrounded by attention, repetition and trust. This does not prove that such practices cure the underlying illness. It does show that the experience of treatment is never determined solely by its chemical or technical components.
The same effect can be recognised in songs and established customs. A lullaby soothes not only through its words, but also through voice, repetition, proximity and rhythm. A processional song or battle song brings people into a shared state and makes hope, fear or courage tangible before they are reasoned through. Words do not operate separately from the situation in which they are spoken or sung.
Modern placebo research confirms part of this old practical knowledge. Expectation, ritual and the meaning of a treatment can influence experienced pain, tension, nausea and other complaints. This does not mean that expectation can arbitrarily cure every illness, or that a physical condition exists only “in the mind.” It means that the experience of symptoms is also influenced by how a treatment is offered, understood and expected.
Seen in this way, the critical factor is not separate from ordinary life. It appears not only in the hypnotist’s consulting room, but also at the kitchen table, in a church pew, beside a sickbed, in a song sung again and again, and in a ritual that inspires trust. Everywhere, words and actions are received by people who have already experienced something, fear something, hope for something and expect something.
Does the critical factor exist?
Does the critical factor really exist? If the term refers to a separate agency that evaluates suggestions one by one, the answer is no. There is no inner counter where a clerk stamps thoughts “admitted” or “refused.”
As a practical name, however, the concept does refer to a real phenomenon. New information is assessed in connection with earlier experiences, expectations, emotions, convictions and social relationships. This judgement may be conscious and reasoned, but it may also be rapid, physical and barely noticeable.
Autosuggestion as a sales message. Even decades after the Coué craze, his phrase was still recognised and used. This 1956 advertisement for Blue Swan underwear opens with “every day in every way… better and better” and promises daily progress and a better self-image.
People are therefore open to influence, but not without a will of their own. They can reject a suggestion because it conflicts with what they consider true or possible. They can also accept it when it connects with trust, expectation or experience. The critical factor is therefore not a separate component of the mind, but a simplifying name for a complex process of judgement and meaning-making.
Back to Coué
This brings us back to Coué’s postcard. The small staircase from I hope to I think and I know appears simple at first: a thought is repeated, gains weight and gradually changes into conviction. The history behind it shows that this movement is never automatic.
Between hope and certainty lies an entire inner landscape. Memory, imagination, habit, fear, desire, trust, upbringing and environment all interact within it. A suggestion is not simply accepted because it is spoken. It is received by someone who already has a history.
That is why the critical factor is more than a concept from hypnosis. It is a practical name for an old human problem: what leads a person to hold something as true? Plato spoke of shadows in a cave, the Stoics of impression and assent, popular wisdom of deceptive appearances, and modern psychology of schemas, expectation and predictive processing. The same question keeps returning: how does something become plausible, credible or true?
This applies in the therapist’s consulting room, but also in the classroom, the courtroom, the voting booth, the living room and the hospital ward. Everywhere, new impressions are compared with existing convictions. Everywhere, people search for coherence between what they already know and what they cannot yet place.
The power of Coué’s formula. Postcard from around 1920-1930 that makes Coué’s phrase “Day by day, in every way, I’m getting better and better” cheerful and easy to remember. This is one of the ways autosuggestion spread through popular visual culture.
Political propaganda also works, or fails, within this field of tension. It is not accepted merely because it is repeated often, but because it connects with existing fears, desires, group feelings or distrust. It is rejected when it conflicts with experiences, values or convictions that are stronger than the message itself.
The value of the concept therefore does not lie in the idea of a small inner gatekeeper that approves or rejects suggestions. Its value lies in the insight that conviction is never only a matter of information. Anyone who wants to reach, mislead, reassure, educate or heal another person must understand what that person already believes, fears, hopes and has experienced.
The path from I hope to I know is not a straight staircase. It runs through experience, meaning and trust. Sometimes an old conviction keeps the door closed. Sometimes a new experience makes possible what previously seemed unthinkable. And sometimes change begins precisely where a thought still sounds hesitant: I hope.