Psychological Phenomena
Observed Human Behaviours And Mental Processes
Psychological effects that defy expectations
Ambiguity effect
The ambiguity effect is a cognitive tendency where decision making is affected by a lack of information, or "ambiguity". The effect implies that people tend to select options for which the probability of a favorable outcome is known, over an option for which the probability of a favorable outcome is unknown.
Anchoring effect
The anchoring effect is a psychological phenomenon in which an individual's judgments or decisions are influenced by a reference point or "anchor" which can be completely irrelevant.
Assembly bonus effect
An assembly bonus effect requires a demonstration of group performance which exceeds the most capable group member or the combined contributions of individual group members. There is evidence for both task-specific assembly bonus effects, and a general effect of collective intelligence, analogous to that of general intelligence.
Audience effect
This is a social phenomenon in which being in the presence of others improves individual task performance. That is, people do better on tasks when they are with other people rather than when they are doing the task alone. Situations that elicit social facilitation include coaction, performing for an audience, and appears to depend on task complexity.
Baader–Meinhof effect
This is a cognitive bias in which a person notices a specific concept, word, or product more frequently after recently becoming aware of it.
Barnum effect
This is a common psychological phenomenon whereby individuals give high accuracy ratings to descriptions of their personality that supposedly are tailored specifically to them, yet which are in fact vague and general enough to apply to a broad range of people. This effect can provide a partial explanation for the widespread acceptance of some paranormal beliefs and practices, such as astrology, fortune telling, aura reading, and some types of personality tests.
Bezold effect
This is an optical illusion where a color may appear different depending on its relation to adjacent colors.
Birthday-number effect
The birthday-number effect is the subconscious tendency of people to prefer the numbers in the date of their birthday over other numbers. The birthday-number effect has been replicated in various countries. It holds across age and gender. The effect is most prominent for numbers over 12.
Boomerang effect
The boomerang effect is a situation where people tend to pick the opposite of what something or someone is saying or doing because of how it is presented to them. Typically, the more aggressively a position is presented to someone, the more likely they are to adopt an opposing view.
Bouba/kiki effect
This is a non-arbitrary mental association between certain speech sounds and certain visual shapes.
Bystander effect
Individuals are less likely to offer help to a victim in the presence of other people. If a single individual is asked to complete a task alone, the sense of responsibility will be strong, and there will be a positive response; however, if a group is required to complete a task together, each individual in the group will have a weak sense of responsibility, and will often shrink back in the face of difficulties or responsibilities.
Cheerleader effect
People will perceive individuals as more attractive when seen in a group than when seen alone.
Cinderella effect
The phenomenon of a higher incidence of child abuse and mistreatment by stepparents than biological parents.
Cocktail party effect
A phenomenon wherein the brain focuses a person's attention on a particular stimulus, usually auditory. This focus excludes a range of other stimuli from conscious awareness, as when a partygoer follows a single conversation in a noisy room. This ability is widely distributed among humans, with most listeners more or less easily able to portion the totality of sound detected by the ears into distinct streams, and subsequently to decide which streams are most pertinent, excluding all or most others.
Contrast effect
A contrast effect is the enhancement or diminishment, relative to normal, of perception, cognition or related performance as a result of successive (immediately previous) or simultaneous exposure to a stimulus of lesser or greater value in the same dimension.
Coolidge effect
The Coolidge effect is a biological phenomenon seen in animals, whereby males exhibit renewed sexual interest whenever a new female of reproductive availability is introduced, even after sex with prior but still available sexual partners. To a lesser extent, the effect is also seen among females with regard to their mates.
Crespi effect
The Crespi effect is a behavioural contrast phenomenon observed in classical conditioning in which a conditioned response changes disproportionately to a suddenly changed reinforcement.
Cross-race effect
This is the tendency to more easily recognize faces that belong to one's own racial group, or racial groups that one has been in contact with.
Curse of knowledge
This is a cognitive bias that occurs when a person who has specialized knowledge assumes that others share in that knowledge.
Diderot effect
The Diderot effect is a phenomenon that occurs when acquiring a new possession leads to a spiral of consumption that results in the acquisition of even more possessions.
Dunning–Kruger effect
The Dunning–Kruger effect is a cognitive bias in which people with limited competence in a particular domain overestimate their abilities.
Einstellung effect
This is the development of a mechanized state of mind. Often called a problem solving set, Einstellung refers to a person's predisposition to solve a given problem in a specific manner even though better or more appropriate methods of solving the problem exist.
Endowment effect
This is the finding that people are more likely to retain an object they own than acquire that same object when they do not own it.
Face superiority effect
This refers to the phenomena of how all individuals perceive and encode other human faces in memory. Rather than perceiving and encoding single features of a face (nose, eyes, mouth, etc.), we perceive and encode a human face as one holistic unified element.
False fame effect
This is a type of memory error where the source of a memory is incorrectly attributed to some specific recollected experience.
False-consensus effect
This is a pervasive cognitive bias that causes people to assume that their personal qualities, characteristics, beliefs, and actions are relatively widespread through the general population.
False-uniqueness effect
This is an attributional type of cognitive bias in social psychology that describes how people tend to view their qualities, traits, and personal attributes as unique when in reality they are not. This bias is often measured by looking at the difference between estimates that people make about how many of their peers share a certain trait or behaviour and the actual number of peers who report these traits and behaviours.
Fan effect
This is a psychological phenomenon where recognition times or error rate for a particular concept increases as more information about the concept is acquired.
Florence Nightingale effect
The Florence Nightingale effect is a trope where a caregiver falls in love with their patient, even if very little communication or contact takes place outside of basic care. Feelings may fade once the patient is no longer in need of care.
Flynn effect
The Flynn effect is the substantial and long-sustained increase in both fluid and crystallized intelligence test scores that were measured in many parts of the world over the 20th century. When intelligence quotient (IQ) tests are initially standardized using a sample of test-takers, by convention the average of the test results is set to 100 and their standard deviation is set to 15 or 16 IQ points. When IQ tests are revised, they are again standardized using a new sample of test-takers, usually born more recently than the first; the average result is set to 100. When the new test subjects take the older tests, in almost every case their average scores are significantly above 100.
Framing effect
The Framing effect is a cognitive bias where people’s decisions change depending on how options are framed, even when the options are logically identical.
Generation effect
The generation effect is a phenomenon whereby information is better remembered if it is generated from one's own mind rather than simply read.
Golem effect
The Golem effect is a psychological phenomenon in which lower expectations placed upon individuals either by supervisors or the individual themselves lead to poorer performance by the individual.
Google effect
The Google effect is the tendency to forget information that can be found readily online by using Internet search engines.
Halo effect
The halo effect is the tendency for positive impressions of a person, company, country, brand, or product in one area to positively influence one's opinion or feelings.
Hawthorne effect
The Hawthorne effect is a type of human behavior reactivity in which individuals modify an aspect of their behavior in response to their awareness of being observed.
Hedonic treadmill
The hedonic treadmill is the observed tendency of humans to quickly return to a relatively stable level of happiness (or sadness) despite major positive or negative events or life changes.
Hostile media effect
The hostile media effect refers to the tendency for individuals with a strong preexisting opinion on an issue to perceive media coverage as biased against their position's side and favorable of their antagonists' point of view.
Hot-cold empathy gap
A hot-cold empathy gap is a cognitive bias in which people underestimate the influences of visceral drives on their own attitudes, preferences, and behaviors.
Hypersonic effect
The hypersonic effect is a phenomenon which claims that, although humans cannot consciously hear ultrasound (sounds at frequencies above approximately 20 kHz), the presence or absence of those frequencies has a measurable effect on their physiological and psychological reactions.
Imposter syndrome
Impostor syndrome, also known as impostor phenomenon or impostorism, is a psychological experience in which a person suffers from feelings of intellectual and/or professional fraudulence. The subjective experience of perceived self-doubt in one's abilities and accomplishments compared with others, despite evidence to suggest the contrary.
Irrelevant speech effect
The irrelevant speech effect or irrelevant sound effect is the degradation of serial recall of a list when sounds, especially speech sounds, are presented. This occurs even if the list items are presented visually. The sounds do not need to be a language the participant understands, or even a real language; human speech sounds are sufficient to produce this effect.
Kappa effect
The kappa effect or perceptual time dilation is a temporal perceptual illusion that can arise when observers judge the elapsed time between sensory stimuli applied sequentially at different locations. In perceiving a sequence of consecutive stimuli, subjects tend to overestimate the elapsed time between two successive stimuli when the distance between the stimuli is sufficiently large, and to underestimate the elapsed time when the distance is sufficiently small.
Kewpie doll effect
The Kewpie doll effect is a term used in developmental psychology derived from research in ethology to help explain how a child's physical features, such as lengthened forehead and rounded face, motivate the infant's caregiver to take care of them. The child's physical features are said to resemble a Kewpie doll.
Kinetic depth effect
The kinetic depth effect is the phenomenon whereby the three-dimensional structural form of an object can be perceived when the object is moving. In the absence of other visual depth cues, this might be the only perception mechanism available to infer the object's shape.
Kuleshov effect
The Kuleshov effect is a film editing mental phenomenon by which viewers derive more meaning from the interaction of two sequential shots than from a single shot in isolation.
Lady Macbeth effect
The Lady Macbeth effect is a priming effect in which feelings of shame appear to increase cleaning and cleanliness-seeking responses.
Lake Wobegon effect
The Lake Wobegon effect is a common name for illusory superiority, a natural human tendency to overestimate one's capabilities. The characterization that "all the women are strong, all the men are good-looking, and the children are all above average" has been used to describe a real and pervasive human tendency to overestimate one's achievements and capabilities in relation to others.
Lawn dart effect
The lawn dart effect occurs when fighter aircraft pilots accelerate horizontally at more than 1 standard gravity. The effect occurs when such extreme stimulation to the vestibular system leads to the perception that the aircraft is climbing, prompting the pilot to lower the aircraft's pitch attitude, or drop the nose.
Less-is-better effect
The less-is-better effect is a cognitive bias that causes people to favor a lesser option when it is presented separately, but to prefer the better option when both are presented together.
Levels-of-processing effect
The Levels of Processing model describes memory recall of stimuli as a function of the depth of mental processing. More analysis produce more elaborate and stronger memory than lower levels of processing. Depth of processing falls on a shallow to deep continuum. Shallow processing leads to a fragile memory trace that is susceptible to rapid decay. Conversely, deep processing results in a more durable memory trace.
Martha Mitchell effect
The Martha Mitchell effect occurs when a medical professional labels a patient's accurate perception of real events as delusional, resulting in misdiagnosis.
Matthew effect
The Matthew effect, sometimes called the Matthew principle, is the tendency of individuals to accrue social or economic success in proportion to their initial level of popularity, friends, and wealth. It is sometimes summarized by the adage or platitude "the rich get richer and the poor get poorer".
McCollough effect
The McCollough effect is a phenomenon of human visual perception in which colorless gratings appear colored contingent on the orientation of the gratings. It is an aftereffect requiring a period of induction to produce it. For example, if someone alternately looks at a red horizontal grating and a green vertical grating for a few minutes, a black-and-white horizontal grating will then look greenish and a black-and-white vertical grating will then look pinkish.
McGurk effect
The McGurk effect is a perceptual phenomenon that demonstrates an interaction between hearing and vision in speech perception. The illusion occurs when the auditory component of one sound is paired with the visual component of another sound, leading to the perception of a third sound. The visual information a person gets from seeing a person speak changes the way they hear the sound. If a person is getting poor-quality auditory information but good-quality visual information, they may be more likely to experience the McGurk effect.
Mere-exposure effect
The mere-exposure effect is a psychological phenomenon by which people tend to develop a liking or disliking for things merely because they are familiar with them.
Mere ownership effect
The mere ownership effect is the observation that people who own a good tend to evaluate it more positively than people who do not.
Microwave auditory effect
The microwave auditory effect consists of the human perception of sounds induced by pulsed or modulated radio frequencies. The perceived sounds are generated directly inside the human head without the need of any receiving electronic device.
Misinformation effect
The misinformation effect occurs when a person's recall of episodic memories becomes less accurate because of post-event information. Information presented later interferes with the ability to retain previously encoded information. Individuals have also been shown to be susceptible to incorporating misleading information into their memory when it is presented within a question. Essentially, the new information that a person receives works backward in time to distort memory of the original event.
Missing letter effect
The missing letter effect refers to the finding that, when people are asked to consciously detect target letters while reading text, they miss more letters in frequent function words than in less frequent, content words.
Modality effect
The modality effect refers to how learner performance depends on the presentation mode of studied items.
Mozart effect
The Mozart effect is the theory that listening to the music of Mozart may temporarily boost scores on one portion of an IQ test.
Munchausen syndrome
Factitious disorder imposed on self (FDIS), or Munchausen syndrome, is a complex mental disorder where individuals play the role of a sick patient to receive some form of psychological validation, such as attention, sympathy, or physical care. Factitious disorder imposed on another, which refers to the abuse of another person in order to seek attention or sympathy for the abuser is considered "Munchausen by proxy", and the drive to create symptoms for the victim can result in unnecessary and costly diagnostic or corrective procedures.
Naive realism
Naive realism is the human tendency to believe that we see the world around us objectively, and that people who disagree with us must be uninformed, irrational, or biased.
Name-letter effect
The name-letter effect is the tendency of people to prefer the letters in their name over other letters in the alphabet.
Near-miss effect
The near-miss effect refers to when a player becomes more motivated to continue expending effort because the previous effort "almost succeeded".
Negativity effect
The negativity bias, also known as the negativity effect, is a cognitive bias that, even when positive or neutral things of equal intensity occur, things of a more negative nature (e.g. unpleasant thoughts, emotions, or social interactions; harmful/traumatic events) have a greater effect on one's psychological state and processes than neutral or positive things. In other words, something very positive will generally have less of an impact on a person's behavior and cognition than something equally emotional but negative.
Nocebo effect
A nocebo effect is said to occur when a patient's expectations for a treatment cause the treatment to have a worse effect than it otherwise would have. For example, when a patient anticipates a side effect of a medication, they can experience that effect even if the "medication" is actually an inert substance. The complementary concept, the placebo effect, is said to occur when expectations improve an outcome.
Novelty effect
The novelty effect is the tendency for performance to initially improve when new technology is instituted, not because of any actual improvement in learning or achievement, but in response to increased interest in the new technology.
Numerosity adaptation effect
The numerosity adaptation effect is a perceptual phenomenon in numerical cognition which demonstrates non-symbolic numerical intuition and exemplifies how numerical percepts can impose themselves upon the human brain automatically.
Observer-expectancy effect
The observer-expectancy effect is a form of reactivity in which a researcher's cognitive bias causes them to subconsciously influence the participants of an experiment. Confirmation bias can lead to the experimenter interpreting results incorrectly because of the tendency to look for information that conforms to their hypothesis, and overlook information that argues against it. It is a significant threat to a study's internal validity, and is therefore typically controlled using a double-blind experimental design.
Out-group homogeneity effect
The out-group homogeneity effect is the perception of out-group members as more similar to one another than are in-group members, e.g. "they are alike; we are diverse".
Overconfidence effect
The overconfidence effect is a well-established bias in which a person's subjective confidence in their judgments is reliably greater than the objective accuracy of those judgments, especially when confidence is relatively high.
Overjustification effect
The overjustification effect occurs when an expected external incentive such as money or prizes decreases a person's intrinsic motivation to perform a task.
Peltzman effect
The Peltzman effect is a theory which suggests that people typically adjust their behaviour in response to perceived levels of risk, becoming more careful where they sense greater risk and less careful if they feel more protected.
Perruchet effect
The Perruchet effect is a psychological phenomenon in which a dissociation is shown between conscious expectation of an event and the strength or speed of a response to the event.
Picture superiority effect
The picture superiority effect refers to the phenomenon in which pictures and images are more likely to be remembered than words.
Placebo effect
The placebo effect is a phenomenon where a person's health improves due to their belief in a treatment's effectiveness, even when the treatment itself has no active medicinal properties.
Pluralistic ignorance
Pluralistic ignorance is a phenomenon in which people mistakenly believe that others predominantly hold an opinion different from their own. In this phenomenon, most people in a group may go along with a view they do not hold because they think, incorrectly, that most other people in the group hold it.
Positivity effect
The positivity effect is the ability to constructively analyze a situation where the desired results are not achieved, but still obtain positive feedback that assists one's future progression.
Pratfall effect
The pratfall effect is the tendency for interpersonal appeal to change after an individual makes a mistake, depending on the individual's perceived competence. In particular, highly competent individuals tend to become more likeable after committing mistakes, while average-seeming individuals tend to become less likeable even if they commit the same mistake.
Precedence effect
When two versions of the same sound presented are separated by a sufficiently short time delay (below the listener's echo threshold), listeners perceive a single auditory event; its perceived spatial location is dominated by the location of the first-arriving sound (the first wave front). The lagging sound does also affect the perceived location; however, its effect is mostly suppressed by the first-arriving sound.
Primacy effect
The primacy effect (also known as the primacy bias) is a cognitive bias that results in a subject recalling primary information presented better than information presented later on. For example, a subject who reads a sufficiently long list of words is more likely to remember words toward the beginning than words in the middle.
Pseudocertainty effect
The pseudocertainty effect is the tendency for people to perceive an outcome as certain while it is actually uncertain in multi-stage decision making. The evaluation of the certainty of the outcome in a previous stage of decisions is disregarded when selecting an option in subsequent stages.
Purkinje effect
This is the tendency for the peak luminance sensitivity of the eye to shift toward the blue end of the color spectrum at low illumination levels as part of dark adaptation. In consequence, reds will appear darker relative to other colors as light levels decrease.
Pygmalion effect
The Pygmalion effect is a psychological phenomenon in which high expectations lead to improved performance in a given area and low expectations lead to worse performance.
Rashomon effect
The Rashomon effect is the phenomenon of the unreliability of eyewitnesses. The effect is named after Akira Kurosawa's 1950 Japanese film Rashomon, in which a murder is described in four contradictory ways by four witnesses. It has been used as a storytelling and writing method in cinema in which an event is given contradictory interpretations or descriptions by the individuals involved, thereby providing different perspectives and points of view of the same incident.
Rhyme-as-reason effect
The rhyme-as-reason effect, also known as the Eaton–Rosen phenomenon, is a cognitive bias where sayings or aphorisms are perceived as more accurate or truthful when they rhyme.
Ringelmann effect
The Ringelmann effect is the tendency for individual members of a group to become increasingly less productive as the size of their group increases.
Self-fulfilling prophecy
A self-fulfilling prophecy is a prediction that comes true at least in part as a result of a person's belief or expectation that the prediction would come true. In the phenomena, people tend to act the way they have been expected to in order to make the expectations come true. Self-fulfilling prophecies are an example of the more general phenomenon of positive feedback loops. A self-fulfilling prophecy can have either negative or positive outcomes. Merely applying a label to someone or something can affect the perception of the person/thing and create a self-fulfilling prophecy. Interpersonal communication plays a significant role in establishing these phenomena as well as impacting the labeling process.
Self-reference effect
The self-reference effect is a tendency for people to encode information differently depending on whether they are implicated in the information. When people are asked to remember information when it is related in some way to themselves, the recall rate can be improved.
Serial position effect
Serial-position effect is the tendency of a person to recall the first and last items in a series best, and the middle items worst.
Simon effect
The Simon effect is the difference in accuracy or reaction time between trials in which stimulus and response are on the same side and trials in which they are on opposite sides, with responses being generally slower and less accurate when the stimulus and response are on opposite sides.
Sleeper effect
The sleeper effect is a psychological phenomenon that relates to persuasion. It is a delayed increase in the effect of a message that is accompanied by a discounting cue, typically being some negative connotation or lack of credibility in the message, while a positive message may evoke an immediate positive response which decays over time.
Social facilitation
Social facilitation is a social phenomenon in which being in the presence of others improves individual task performance. That is, people do better on tasks when they are with other people rather than when they are doing the task alone. Situations that elicit social facilitation include coaction, performing for an audience, and appears to depend on task complexity.
Spacing effect
The spacing effect demonstrates that learning is more effective when study sessions are spaced out. This effect shows that more information is encoded into long-term memory by spaced study sessions, also known as spaced repetition or spaced presentation, than by massed presentation ("cramming").
Spotlight effect
The spotlight effect is the psychological phenomenon by which people tend to believe they are being noticed more than they really are. Being that one is constantly in the center of one's own world, an accurate evaluation of how much one is noticed by others is uncommon. The reason for the spotlight effect is the innate tendency to forget that although one is the center of one's own world, one is not the center of everyone else's. This tendency is especially prominent when one does something atypical.
Stockholm syndrome
Stockholm syndrome is a proposed condition or theory that tries to explain why hostages sometimes develop a psychological bond with their captors.
Stroop effect
The Stroop effect is the delay in reaction time between neutral and incongruent stimuli.
Subadditivity effect
The subadditivity effect is the tendency to judge probability of the whole to be less than the probabilities of the parts.
Subject-expectancy effect
The subject-expectancy effect is a form of reactivity that occurs when a research subject expects a given result and therefore unconsciously affects the outcome, or reports the expected result. Because this effect can significantly bias the results of experiments (especially on human subjects), double-blind methodology is used to eliminate the effect.
Tamagotchi effect
The Tamagotchi effect is the development of emotional attachment with machines, robots or software agents.
Telescoping effect
The telescoping effect (or telescoping bias) refers to the temporal displacement of an event whereby people perceive recent events as being more remote than they are and distant events as being more recent than they are. The former is known as backward telescoping or time expansion, and the latter as is known as forward telescoping.
Testing effect
The testing effect (also known as retrieval practice, active recall, practice testing, or test-enhanced learning) suggests long-term memory is increased when part of the learning period is devoted to retrieving information from memory.
Tetris effect
The Tetris effect occurs when someone dedicates vast amounts of time, effort and concentration on an activity which thereby alters their thoughts, dreams, and other experiences not directly linked to said activity.
Thatcher effect
The Thatcher effect or Thatcher illusion is a phenomenon where it becomes more difficult to detect local feature changes in an upside-down face, despite identical changes being obvious in an upright face.
Ventriloquism effect
The ventriloquism effect which refers to the perception of speech sounds as coming from a direction other than their true direction, due to the influence of visual stimuli from an apparent speaker. Thus, when the ventriloquism illusion occurs, the speaker's voice is visually captured at the location of the dummy's moving mouth (rather than the speaker's carefully unmoving mouth).
Venus effect
The Venus effect is a phenomenon in the psychology of perception, where viewers of paintings, such as Venus, have the impression that the Venus is admiring her own reflection in the mirror. However the viewer sees the face of Venus in the mirror, and they are not directly behind her, therefore what Venus sees in the reflection cannot be the same as what the viewer sees. It would be more logical if the viewer were to conclude that Venus is looking at the reflection of the viewer, or in the case of the original setting, the reflection of the painter. This highlights that most people may hold beliefs that are inconsistent with observable phenomena.
Von Restorff effect
The Von Restorff effect, also known as the "isolation effect", predicts that when multiple homogeneous stimuli are presented, the stimulus that differs from the rest is more likely to be remembered.
Wagon-wheel effect
The wagon-wheel effect (alternatively called stagecoach-wheel effect) is an optical illusion in which a spoked wheel appears to rotate differently from its true rotation. The wheel can appear to rotate more slowly than the true rotation, it can appear stationary, or it can appear to rotate in the opposite direction from the true rotation (reverse rotation effect).
Well travelled road effect
The well travelled road effect is a cognitive bias in which travellers will estimate the time taken to traverse routes differently depending on their familiarity with the route. Frequently travelled routes are assessed as taking a shorter time than unfamiliar routes.
Werther effect
The Werther effect is a spike in emulation suicides after suicide is widely publicized.
Westermarck effect
The Westermarck effect, also known as reverse sexual imprinting, is a psychological hypothesis that states that people tend not to be attracted to peers with whom they lived like siblings before the age of six.
Word frequency effect
The word frequency effect is a psychological phenomenon where recognition times are faster for words seen more frequently than for words seen less frequently. Word frequency depends on individual awareness of the tested language. The phenomenon can be extended to different characters of the word in non-alphabetic languages such as Chinese.
Word superiority effect
The word superiority effect (WSE) refers to the phenomenon that people have better recognition of letters presented within words as compared to isolated letters and to letters presented within nonword (orthographically illegal, unpronounceable letter array) strings.
Worse-than-average effect
The worse-than-average effect or below-average effect is the human tendency to underestimate one's achievements and capabilities in relation to others.
Zeigarnik effect
The Zeigarnik effect occurs when an activity that has been interrupted may be more readily recalled. It postulates that people remember unfinished or interrupted tasks better than completed tasks.