Cognitive Connie
Let's explore Landmark Cases
The experiments and cases that changed psychology forever. From obedience and conformity to memory, attachment, and fear — explore the defining studies that revealed how the mind really works.
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Patient H.M. and the Hippocampus
Henry Molaison — known for decades in the scientific literature only as H.M. — underwent a bilateral medial temporal lobe resection in 1953 at age 27, performed by neurosurgeon William Beecher Scoville at Hartford Hospital. The surgery was intended to relieve severe, intractable epilepsy. It largely succeeded in that aim, but its cognitive consequences were devastating and scientifically transformative: Henry was left with a profound, permanent anterograde amnesia — an almost complete inability to form new long-term declarative memories.
Phineas Gage and the Frontal Lobe
On 13 September 1848, a 25-year-old railroad construction foreman named Phineas Gage was preparing a rock face in Cavendish, Vermont, when a premature explosion drove a 13-pound iron tamping rod through his skull. The rod entered below his left cheekbone, passed behind his left eye, traversed the frontal lobe, and exited through the top of his head — landing some 25 metres away. Gage survived. He walked to the cart that took him to a doctor, sat upright during the journey, and within minutes of the accident was conversing with the physician who examined him.
The Milgram Obedience Experiment
In 1961 and 1962, Stanley Milgram at Yale University ran a series of experiments that would permanently change how psychologists understood human obedience to authority. Inspired by the Nuremberg trials and Hannah Arendt's phrase "the banality of evil," Milgram wanted to know how ordinary people — not sadists, not ideological extremists — could follow orders to harm others. To find out, he designed one of the most deceptive and disturbing studies in scientific history.
The Stanford Prison Experiment
In August 1971, Philip Zimbardo and colleagues transformed the basement of the Stanford psychology department into a mock prison. Twenty-four healthy, psychologically screened male volunteers were randomly assigned to play "guards" or "prisoners" for what was planned as a two-week study. It was stopped after six days.
The Asch Conformity Experiments
Between 1951 and 1956, Solomon Asch at Swarthmore College conducted a series of deceptively simple experiments that produced one of the most striking and disturbing findings in social psychology: when a group of people unanimously gives an obviously wrong answer, a significant proportion of individuals will publicly agree — even when the correct answer is unambiguous and the individual can clearly see it for themselves.
Bandura's Bobo Doll Experiment
In 1961 and 1963, Albert Bandura and colleagues at Stanford University conducted a series of experiments that fundamentally challenged the behaviourist orthodoxy that learning occurs only through direct reinforcement and punishment. Using a large inflatable toy clown called a "Bobo doll," Bandura demonstrated that children could acquire entirely new aggressive behaviours — including novel, specific acts they had never performed before — simply by watching an adult model perform them.
Little Albert: Conditioning a Phobia
In 1920, John B. Watson and Rosalie Rayner at Johns Hopkins University published one of the most controversial papers in the history of psychology. Working with an infant known only as "Albert B.," they set out to demonstrate that human emotional responses — specifically fears — could be artificially created through classical conditioning. Their aim was nothing less than to show that behaviourism was a complete psychology: that all human emotions, including the "irrational" fears that psychoanalysts attributed to hidden unconscious conflicts, were simply learned stimulus-response associations.
The Stroop Effect
In 1935, John Ridley Stroop published his doctoral dissertation in the Journal of Experimental Psychology. The paper described a simple but powerful phenomenon that would become one of the most replicated findings in the history of psychology, cited in over ten thousand scientific papers in the following eight decades: when asked to name the ink colour of a colour word printed in a conflicting colour — say, the word "RED" printed in blue ink — people are significantly slower and more error-prone than when the word and colour match. This delay and interference is the Stroop Effect.
Loftus & Palmer: Eyewitness Memory
In 1974, Elizabeth Loftus and John Palmer at the University of Washington published two experiments that permanently altered how psychologists, lawyers, and courts understand eyewitness memory. The question they asked was simple and had enormous practical consequences: can the phrasing of a question about an event alter what a witness "remembers" about that event?
Harlow's Monkeys and Contact Comfort
In the late 1950s, Harry Harlow at the University of Wisconsin-Madison began a series of experiments that would fundamentally alter our understanding of what infants need from their caregivers. The question he set out to answer was one that had been answered for decades by both behaviourists and Freudians: why do infants become attached to their mothers?
Ainsworth's Strange Situation
In 1969, Mary Ainsworth introduced one of the most influential laboratory procedures in developmental psychology: the Strange Situation. Designed to assess the quality of the attachment bond between a toddler and their primary caregiver, it placed a 12–18-month-old in an unfamiliar room and subjected them to a structured sequence of separations from and reunions with the caregiver — each episode carefully timed to activate the infant's attachment system without causing undue distress.
Baillargeon's Violation-of-Expectation Studies
In 1985, Renée Baillargeon published a finding that shook the foundations of Piagetian developmental psychology. Using a technique that measured looking time rather than reaching behaviour, she showed that infants as young as 3½ months appeared to expect objects to continue existing when hidden — months earlier than Piaget had claimed was possible.
Gibson & Walk — The Visual Cliff
In 1960, Eleanor Gibson and Richard Walk published one of the most visually striking experiments in developmental psychology. They constructed a "visual cliff" — a glass-topped table with a shallow side and a deep side, with a patterned surface visible below the glass on both sides — and observed whether infants would crawl across the deep side when called by their mothers.
Mischel's Marshmallow Test
Few psychology studies have captured the public imagination as completely as Walter Mischel's marshmallow test. In the late 1960s and early 1970s at Stanford's Bing Nursery School, Mischel and colleagues placed young children in front of a single marshmallow (or other preferred treat) and offered them a choice: eat it now, or wait for the researcher to return and receive two marshmallows. Most four-year-olds struggled. Some grabbed the treat within seconds; others used elaborate strategies — covering their eyes, singing to themselves, turning away — to delay. The longest waiters held out for up to 15 minutes.
Tronick's Still Face Experiment
In 1978, Edward Tronick and colleagues at Harvard Medical School published what became one of the most emotionally arresting demonstrations in developmental psychology: the still face paradigm. In this simple but powerful procedure, a mother and her 3–6-month-old infant engage in normal, animated face-to-face interaction — the mother smiling, talking, mirroring the baby's expressions. Then, without warning, the mother assumes a neutral, unresponsive "still face" — no smiling, no vocalising, no response to the infant's bids for contact. Within seconds, the infant notices. They try increasingly to re-engage the mother — pointing, reaching, smiling, vocalising. When this fails, many infants withdraw: they look away, their posture slumps, their affect flattens. Some become distressed.
Ebbinghaus — The Forgetting Curve
Hermann Ebbinghaus conducted psychology's first rigorous experiments on memory — using himself as the sole participant. Working in isolation in the 1870s–80s, he memorised thousands of lists of meaningless three-letter syllables (e.g. DAX, BUP, ZOL), then tested how much he retained after varying intervals. His data revealed that forgetting follows a predictable mathematical curve: rapid at first, then levelling off — a finding that has stood up for over 140 years.
Sperling — Iconic Memory
In 1960 George Sperling published one of the most elegant experiments in cognitive psychology. He showed participants a brief flash (50 ms) of a 3×4 grid of letters, then measured how many they could report. Whole-report accuracy averaged only 4–5 letters — implying poor memory. But participants consistently said they could "see" most of the grid during the flash. Sperling tested this claim with a deceptively simple change: instead of asking for all letters, he played a tone immediately after the flash cueing participants to report just one row. Accuracy jumped to near-perfect — they could report any row with ~76% accuracy, suggesting they had access to roughly 9–12 items. The trick was timing: as the delay between flash and tone increased beyond ~300 ms, the advantage evaporated.
Peterson & Peterson — Short-Term Memory
In 1959, Lloyd and Margaret Peterson posed a simple question: how long does a memory last without rehearsal? Their method was elegant. Participants heard a consonant trigram — three unrelated letters such as CHJ or QPW — followed immediately by a three-digit number. They then counted backward in threes from that number aloud (e.g., 397, 394, 391…) until a signal to recall. Counting prevented any form of rehearsal. The result was striking: after just 18 seconds, recall accuracy had plummeted from near-100% to roughly 5–10%.
Craik & Tulving — Levels of Processing
Fergus Craik and Endel Tulving's 1975 paper presented one of the most influential challenges to the multi-store model of memory. Rather than asking how memory is structured (boxes and arrows of stores), they asked how memory is created — what happens at the moment of encoding that determines how well something will be remembered.
Baddeley & Hitch — Working Memory
By the early 1970s, the multi-store model proposed that a single short-term store was the obligatory gateway to long-term memory and reasoning. If that were true, filling STM completely with to-be-remembered digits should cripple any concurrent cognitive task. Alan Baddeley and Graham Hitch set out to test this directly.
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