Freudian slip: what Freud actually claimed, and what the research shows

A Freudian slip is a slip of the tongue, the pen or an action that lets a second intention show through. On Sigmund Freud’s account, this second intention is a thought that the person had held back. Freud described these errors in The Psychopathology of Everyday Life, first published in 1901. In his introductory lectures of 1916, he put the mechanism in one line. Two intentions interfere with each other, and one of them was suppressed first.

So does a slip reveal the unconscious? Not reliably. Freud himself did not claim that every slip has a meaning. Speech research explains most slips by the work of planning speech. Experiments show that what is on a person’s mind can change which slip happens. They do not show that slips expose hidden wishes.

• The best-known example, “re-filled” (in German, “Vorschwein”), does not come from Freud’s patients. It comes from an 1895 collection by the linguist Rudolf Meringer and the psychiatrist Carl Mayer. The speaker had consciously thought “filthy”.
• Freud sorted slips into three groups. Only in the third does the speaker deny the disturbing thought. The everyday idea of a slip that reveals the unconscious fits that group best.
• Freud wrote that he did not assert “that every single mistake which occurs is meaningful”. He accepted that tongue slips may have “a purely physiological basis”.
• Lecture notes by a University of Pennsylvania linguist put the rate at about one slip per thousand words.
• In the laboratory, a frame of mind steered the slips. A set towards electric shocks produced more slips about electricity, and a set towards sex produced more slips about sex.

What is a Freudian slip?

A Freudian slip is a slip that someone reads as a sign of a held-back thought. The APA Dictionary of Psychology places the term in “the popular understanding of psychoanalytic theory”. There, a Freudian slip is an error in writing, speech or action. It is “held to be caused by unacceptable impulses breaking through the ego’s defenses”, and it exposes “the individual’s true wishes or feelings”.

Freud’s own account is narrower. In the fourth of his introductory lectures, in the 1920 English translation, he names two conditions. First, an error arises “through the mutual interference of two intentions”: the one that the speaker means to express and a disturbing one. Second, the disturbing intention must be held back first. In his words, “the suppression of the existing intention to say something is the indispensable condition of the occurrence of a slip”.

For Freud, the slip of the tongue was one member of a family. His second lecture lists errors of speech, slips in writing, misreading, mishearing, the temporary forgetting of names and plans, mislaying, losing and false beliefs. In the German original, most of these words begin with the same prefix, “ver-”: Versprechen, Verlesen, Verhören, Vergessen, Verlegen, Verlieren. The translation says that their “inner connection is expressed in the use of the same prefix”. It can only keep the German words in a footnote.

Freud’s umbrella term was Fehlleistung, a faulty achievement. English uses the word parapraxis, which the Penn lecture notes call a “pseudo-Greek scientism”. The APA Dictionary defines parapraxis as “an error that is believed to express unconscious wishes, attitudes, or impulses”. Our list of psychology terms that do not translate cleanly into German has this pair and others like it.

The famous examples, and where they came from

Many classic Freudian slips did not come from Freud’s consulting room. Several come from the linguist Meringer. Some are in his book of 1895 with Mayer, Versprechen und Verlesen (slips of the tongue and of reading), and one is from a later essay for general readers. Freud’s second lecture calls the two authors “a philologist and a psychiatrist”. Their explanations were often not Freud’s. Other examples come from Freud’s own collection, including one of his own slips.

The second row needs its German to make sense. The speaker wanted to say that facts had come “zum Vorschein” (to light), and he thought of them as “Schweinereien” (filthy business). He said “Vorschwein”. The 1920 translation rebuilds the blend in English as “re-filled”, from “revealed” and “filthy”.

Freud discusses these cases in his chapter on mistakes in speech and in his lectures. In the most famous case, the speaker knew the disturbing thought and confirmed it when asked. Meringer, who collected the case, did not need the unconscious to explain it. For him, it was enough that “Vorschein” and “Schweinerei” sound alike.

What Freud claimed, and what he did not

Freud’s fourth lecture sorts slips into three groups. The groups differ by how far the disturbing thought was pushed back.

1. 1.The speaker knows the disturbing thought and felt it just before the slip. Freud’s example is “re-filled”. The speaker agreed with the judgement “filthy” and had meant to say it, then decided not to.
2. 2.The speaker recognises the thought as their own at once. But the speaker did not know that it was active just before the slip.
3. 3.The speaker “energetically” denies the interpretation. The speaker says that the thought was “at all times completely alien to him”.

The everyday idea that a slip reveals the unconscious fits the third group best. Only there is the thought foreign to the speaker. For this group, Freud assumed a tendency “suppressed for even a longer time, perhaps a very long time”. In the first group, the speaker holds a thought back on purpose. In the second, the speaker accepts the thought afterwards but did not notice it before the slip.

The 1920 translation uses the word “suppression” for all three groups. Today’s terms divide this ground. The APA Dictionary keeps suppression for a conscious effort to put thoughts out of mind, and repression for the unconscious defence. So Freud’s first group is closer to suppression. Our article on defence mechanisms explains the difference between repression and suppression.

Freud was also more careful than his reputation suggests. Three passages show this:

• In the German edition of 1904, he discussed interpretations of other people’s slips. He wrote that they “cannot be proved by anything” (our translation). He asked readers to keep them apart from the cases that he had collected and analysed himself.
• In the fourth lecture, he wrote: “we do not assert—and for our purposes need not assert—that every single mistake which occurs is meaningful, although I consider that probable.” For slips of the tongue and pen, “the occurrences may take place on a purely physiological basis”.
• In the third lecture, he accepted that slight illness, problems of circulation and fatigue play a part. But for him, bodily factors “have only the value of acting by way of facilitation and encouragement”.

So Freud thought that most slips probably have a meaning, but he admitted that he could not prove it. In the third lecture, he wrote: “one cannot prove that a slip of the tongue cannot occur without this mechanism.” His later model of the mind gave the work of defence to the ego. Our article on id, ego and superego explains that model.

The kinds of slips

Meringer and Mayer sorted their slips by form, not by motive. Freud’s second lecture gives their main kinds, with these examples in the 1920 translation.

For Freud, the form mattered less than the source of the disturbance. In his chapter on mistakes in speech, he separated two cases. In the first, the disturbance comes from the same speech, for example a sound that comes too early or echoes too late. In the second, it comes from a thought outside the speech that the speaker did not intend to express. Only the second case is a Freudian slip in the narrow sense.

The psychologist Wilhelm Wundt used the phrase “contact effect of sound” for the influence of nearby sounds on each other. Among his own examples, Freud wrote, he could “scarcely find one” that he had to explain “simply and solely” by it.

Why we make slips: the speech-production view

Linguistics treats a slip as a view into the planning of speech, not into the unconscious. The lecture notes for Penn’s introductory linguistics course describe the load. A speaker chooses “about three words per second out of a vocabulary of 40,000 or more”. At the same time, the speaker produces about five syllables and a dozen speech sounds per second, with more than 100 muscles. Under this load, “about one slip of the tongue on average occurs per thousand words said”.

A simple calculation shows what that rate means. At three words per second, a thousand words take about 330 seconds. So a person who talks without a pause makes a slip about every five to six minutes. Most of what people say comes out as planned.

Slips happen at every level of the plan, from whole phrases down to single sounds. The notes quote examples that the psycholinguist Gary Dell built around one target sentence, “I wanted to read the letter to my grandmother”:

• exchange of words: “I wanted to read my grandmother to the letter”
• substitution of a word: “I wanted to read the envelope to my grandmother”
• anticipation of a sound: “I wanted to read the gretter to my grandmother”
• a sound feature that comes too early or too late: “I wanted to read the letter to my brandmother”

The notes conclude that research since 1901 “tends to undermine Freud’s conception”. On this view, slips “tell us much less than Freud thought about unconscious intentions, and much more about language structure and use”. The author of the notes, the Penn linguist Mark Liberman, made the same point on Language Log in 2024. In his words, “a more parsimonious theory would be that speech errors occur simply because talking is a cognitively complex and difficult task”.

Current models describe slips as failures of error control. Thieffry and colleagues summarise two approaches in a 2023 paper. In Levelt’s model, a self-monitoring system checks the planned utterance. In Dell and Reich’s model, a word also activates related words, and feedback corrects errors. The authors see a link to Freud here. Freud quoted two factors from Wundt: the “uninhibited stream” of sound and word associations, and the relaxation of the attention that holds it back. He called Wundt’s observations “absolutely justified and very instructive”.

What experiments show about Freudian slips

From the 1970s, researchers produced slips in the laboratory. The method is called the SLIP technique, for “spoonerisms of laboratory induced predisposition”. Thieffry and colleagues describe it. Participants read word pairs silently, and a signal tells them to say some pairs aloud. Pairs such as “barred dorm” and “bought dog” come before the target “darn bore”. The target can then come out as “barn door”.

Three findings matter for Freud’s idea:

• A frame of mind changes which slips happen. In a study by Michael Motley and Bernard Baars (1979), the word pairs had equal chances of producing slips about electricity or about sex. Participants with a set towards electric shocks made more electricity slips. Participants with a set towards sex made more sex slips. A neutral set produced no difference. A second study by the same group supported the prediction that personality and situation affect which slips the inner check lets through.
• Speakers often catch embarrassing slips. Thieffry and colleagues report that Motley and colleagues, in 1981 and 1982, found that participants intercept taboo errors more often than neutral ones. The researchers proposed a check before speech. In 2011, Severens and colleagues recorded brain activity during the task. Some trials could produce a taboo word. On these trials, they found a stronger negative wave about 600 milliseconds after the cue to speak, even when no error was heard. The authors concluded that the brain can detect and correct taboo utterances internally.
• Newer results are mixed. Thieffry and colleagues tested 55 people with a French version of the task, with 32 neutral and 32 taboo spoonerisms. The participants made 37 slips in total, with no significant difference between taboo and neutral slips. The researchers split the group with a social desirability scale, which they read as a measure of defensiveness. The researchers then allowed for the starting difference between the two kinds of slip. After that, highly defensive participants made 2.7 times as many taboo slips as lowly defensive ones. The sample is small, and the authors interpret their data in a psychoanalytic framework.

So what follows? The experiments support one part of Freud’s idea: what occupies a person can shape the form of a slip. That fits Freud’s first group. But the experiments do not test the third group, which is about wishes held back for a long time that the speaker denies. Several studies also suggest that speakers often catch embarrassing slips before anyone hears them.

Freudian slip, spoonerism, malapropism: which is which

Many slips that people call Freudian have names of their own. These names describe the form of the error. “Freudian” describes one explanation of it.

A spoonerism, a malapropism or a blend can each be read as a Freudian slip. “Barn door” for “darn bore” is a Freudian slip only if a held-back thought caused it. The form of the error cannot settle that question. Only the speaker’s thoughts can.

When a slip is not worth interpreting

Slips are normal. Freud opened his second lecture with errors that “have nothing to do with the pathological, inasmuch as they can be observed in every normal person”.

A person who interprets someone else’s slip has Freud’s own problem. Without asking, nobody can check which thought was behind it. Even for “re-filled”, the answer came only when the speaker was asked. Freud admitted the same about “inscort”: he and his audience had accepted the escort-and-insult reading “without demanding proof of it”.

One exception concerns health. A sudden change in speech is not an everyday slip. According to the CDC, “sudden confusion, trouble speaking, or difficulty understanding speech” is a sign of stroke. If you see this in yourself or in someone else, call 9-1-1 (or your local emergency number) right away.

Keeping the terms apart

Parapraxis, slip of the tongue, spoonerism, repression and suppression sit close together, and they are easy to mix up in an exam. In Psychology World you can save terms like these to one list. Then you can drill the list as flashcards, as multiple-choice questions once it has four or more terms, or by typing the answer. What each study mode does is set out on the home page. Our guide to memorising psychology terminology explains which study methods have the strongest evidence.