40 studies that changed psychology

Gazzaniga (One brain or two)

Explored the independent functions of the left and right brain hemispheres in split-brain patients. Found that each hemisphere, when isolated, acts as a separate mind with consciousness and capabilities. Left: speaking, writing, math, and reading. Right: facial recognition, spatial reasoning, artistic activities.

More experience = bigger brain (Rosenzwieg)

Believed that animals raised in highly stimulating environments will demonstrate differences in brain growth and chemistry. Found that an enriched environment produced brain differences in rats. Larger brain cells, thicker cerebral cortex’s, more glial cells, and larger synapses. 

Are you a natural? (Bouchard)

Genetically identical humans that are raised separately and in different settings grew into adults with extremely similar characteristics. It suggests that genes have contributed to traits in personality and intelligence. Nature vs nurture. 

Watch out for the visual cliff! (Gibson)

Explored infants' perception of depth. Babies hesitated to crawl on a surface that appeared to have a drop off, suggesting that we're born with depth cues and perception. Depth perception is biological and not a product of experience. 

Turnbull (What you see is what you’ve learned)

Highlights the idea that our perceptions and understanding of the world are shaped by experiences and cultural context. Suggests that we observe the world through the lens of prior learning. 

To sleep, no doubt to dream (Aserinsky and Klietman)

Wanted to find if people could function normally if their dream life (REM sleep) was completely or partially suppressed. Found that we need to dream, and if we don’t dream, we’ll experience REM rebound.

(Un)Romancing the dream (Hobson and McCarly)

Suggests that dreams are a byproduct of brain activity during REM sleep (not symbolic meaning).

Acting as if you are hypnotized (Spanos)

Participants expect to relinquish control over their own behav- ior, and as the process of hypnotic induction develops, they begin to believe that their voluntary acts are becoming automatic, involuntary events.

It’s not just about salivating dogs (Pavlov)

Studies classical conditioning through dogs that learned to expect food following the appearance of certain signals. It helps explain behaviors like phobias and other emotional responses. Focuses on reflex behavior (behaviors that are not voluntarily controlled). 

Little emotional Albert (Watson and Rayner)

Demonstrates that all human behavior stems from learning and conditioning. Studies classical conditioning by pairing a rat (neutral stimulus) with a loud noise, which naturally elicits fear. After repeated pairings, Albert would begin to fear the rat in the absence of the noise. Classical conditioning.

Knock Wood (Skinner)

Demonstrated how noncontingent reinforcement can lead to superstitious behavior. Doing behaviors that did not affect the outcome (false associations). 

See aggression do aggression (Bandura)

It demonstrates how children can acquire behaviors by observing adults. 

What you expect is what you get (Rosenthal and Jacobson)

Leads to the self-fulfilling prophecy where higher expectations lead to improved performance in students. This study shows that teachers' expectations can significantly influence student achievement and behavior, creating a cycle where expected outcomes manifest.

Just how are you intelligent (Gardner)

Proposes that intelligence is not a single entity but a collection of distinct abilities. Identities eight types of intelligence. Also, people are not born with all the intelligence they will ever have. 

Maps in your mind (Tolman)

Explored how humans internally represent and utilize spatial knowledge, often referred to as cognitive maps. Studied rats' ability to memorize a maze. 

Thanks for the memories (Loftus)

Found that when an event is recalled, it’s not accurately recreated. Memories are not stable, but malleable, and change over time. Reconstructive memory is a result of new and existing information to fill in the gaps in your recall of an experience. Memories are susceptible to deception and misinformation. 

Discovering love (Harlow)

Demonstrated that attachment and love are primarily based on comfort and contact, rather than the provision of food. Baby monkeys prefer the cloth mother to the wire mother. 

Out of sight, but not out of mind (Piaget)

Studies object permanence. Examined infants' ability to understand that objects continue to exist even when hidden from view. Theorized that all children develop through four stages of cognitive development. 

How moral are you? (Kohlberg)

Proposed that individuals progress through six stages of moral reasoning, moving from a stage where morality is based on external rules, to one where it’s based on abstract ethical principles. Highlights that the reasoning behind moral dilemmas, rather than the actions themselves, is a key indicator of moral development. 

In control and glad of it (Langer and Rodin)

Enhanced personal responsibility and control in nursing home residents led to significant improvements in physical and mental well-being. 

I can see it all over your face (Eikman and Friesen)

Explored whether facial expressions are universal or culturally determined. The “facial feedback theory” of emotional expression states that expression on your face actually feeds information back to your brain to assist you in interpreting the emotion you are experiencing. Also, found that display rules can dictate how emotions are expressed across cultures. 

Life, change, and stress (Holmes and Rahe)

Identified the Social Readjustment Rating Scale (SRRS), which ranks life events based on their impact on stress levels, establishing a link between life changes and health outcomes.

Thoughts out of tune (Festigner and Carlsmith)

Studies cognitive dissonance. Found that when a person is asked to do something that is contrary to their opinion, they will be more likely to change their opinion to bring it into correspondence with what they have said or done. People who have strong justification feel less dissonance than those who have a small justification. 

Are you the master of your fate? (Rotter)

Explored the concept of locus of control, distinguishing between internal and external factors influencing individuals' beliefs about control over their lives. Those with an internal locus believe they can influence outcomes through their actions, while those with an external locus attribute outcomes to fate or external circumstances. Subjects with a lack of belief in their internal locus of control have higher rates of depression.

Racing against your heart (Freidman and Rosenman)

Found that Type A people experience more blood clots and higher levels of cortisol than type B people. Establishes a relationship between personality and illness and highlights the role of stress in heart disease.

The one; The many (Triandis)

Investigated the differences between individualistic and collectivistic cultures, showing how these orientations influence behavior, values, and social interactions. Cultures that emphasize individuality prioritize personal goals, while those that value collectivism prioritize group harmony. Collectivist’s are more prone to illness.

Who’s crazy here, anyway? (Rosenhan)

A landmark study that challenged the validity of psychiatric diagnoses by showing how individuals identified as mentally ill behave normally when not labeled. The study highlighted the impact of labeling and the potential for misdiagnosis in mental health treatment.

You’re getting defensive again! (Freud)

A concept from the psychoanalytic theory that describes the psychological mechanisms individuals use to protect their self-esteem and justify their behaviors. It emphasizes how people often react defensively when their ego is threatened. They are defense mechanisms to avoid unpleasant anxiety.

Learning to be depressed (Seligman and Maier)

Studies learned helplessness. Determined that individuals are more likely to be depressed if they have learned to attribute their lack of control to causes that are permanent, related to factors within their own personality, and pervasive across many areas of their life. 

Crowding in the behavioral sink

A concept introduced by John B. Calhoun that describes the negative effects of high population density on behavior, leading to increased aggression, withdrawal, and social breakdown among individuals.

Choosing your psychotherapist

Involves selecting a mental health professional based on personal needs, therapeutic approach, and compatibility, which can significantly impact treatment effectiveness.

Relaxing your fears away (Wolpe)

A therapeutic approach developed that utilizes systematic desensitization to help individuals overcome phobias and anxiety by gradually exposing them to feared stimuli while teaching relaxation techniques.

Projections of who you are (Rorschach)

A psychological test that uses ambiguous inkblots to explore an individuals perceptions and thought processes.The test is based on the principle of projective theory, where subjects are asked to describe what they see in the inkblots, and these descriptions are then analyzed to reveal underlying personality traits, emotional states, and thought patterns.

Picture this (Murray)

A projective psychological assessment tool that uses a series of ambiguous pictures to elicit stories from participants. These stories are then analyzed to reveal insights into a person's personality, needs, motivations, and emotional conflicts.

Not practicing what you preach (Lapeire)

Contrary to prevailing beliefs, people's social actions track very poorly with their spoken social attitudes. In other words, what people say is often not what they do.

The power of conformity (Asche)

Wanted to find out how powerful the need to conform is in influencing our behavior. If people are willing to conform to a group of people they hardly know about a clearly incorrect judgment, how strong must this influence be in real life?

To help or not to help (Darley)

Often referred to as the "bystander effect" study, demonstrated that the presence of more bystanders significantly reduces the likelihood of an individual offering help in an emergency. This phenomenon, explained by the concept of "diffusion of responsibility," suggests that individuals feel less personal responsibility to act when others are present, assuming someone else will intervene. 

Obey at any cost (Milgram)

Ordinary people are surprisingly willing to obey authority figures, even when it means inflicting pain on others. Participants were instructed to administer increasingly severe electric shocks to a learner