Karl Lashley
A pioneering neuroscientist who hunted for the physical seat of memory in the brain, reshaping how we understand learning.
1890–1958 (age 68)·American psychologist·Birthday: June 7·The Lost Generation
Biography
Karl Lashley spent a lifetime in the lab, methodically probing the brain's mysteries with scalpel and experiment. Trained as a psychologist under John B. Watson, he became fascinated by the biological basis of behavior. His most famous work involved teaching rats complex mazes, then surgically removing specific portions of their cerebral cortex to see what was forgotten. To his surprise, he found that memory loss depended not on the location of the damage, but on its amount—a principle he called mass action. He also proposed the idea of equipotentiality, suggesting that within certain brain areas, one part could take over for another. Though some of his specific theories were later refined, Lashley's rigorous, physiological approach helped steer psychology away from pure behaviorism and laid crucial groundwork for the modern field of cognitive neuroscience.
The Lost Generation
1883–1900
Came of age during World War I. Disillusioned by the carnage, they rejected the certainties of the Victorian era and built modernism from the wreckage — in art, literature, and politics.
Karl was born in 1890, placing them squarely in The Lost Generation. The events that shaped this generation — world wars, depression, and rapid industrialization — shaped the world they entered and the choices available to them.
#1 When Karl Was Born
The biggest hits of 1890
Karl's Life & Times
The world at every milestone
1890Born
Wounded Knee massacre marks the end of the Indian Wars
President: Benjamin Harrison
1895Started school
First public film screening by the Lumiere brothers
President: Grover Cleveland
1903Became a teenager
Wright brothers achieve first powered flight
President: Theodore Roosevelt
1906Could drive
San Francisco earthquake devastates the city
President: Theodore Roosevelt
1908Could vote
Ford Model T goes into production
President: Theodore Roosevelt
1911Turned 21
Triangle Shirtwaist Factory fire kills 146 in New York
President: William Howard Taft
1920Turned 30
Women gain the right to vote in the US
Home: $3,395President: Woodrow Wilson"Swanee" — Al Jolson
1930Turned 40
Pluto discovered
Gas: $0.20/galHome: $3,510President: Herbert Hoover"Body and Soul" — Paul WhitemanBest Picture: All Quiet on the Western Front
1940Turned 50
The Blitz: Germany bombs London
Gas: $0.18/galHome: $2,938Min wage: $0.30/hrPresident: Franklin D. Roosevelt"I'll Never Smile Again" — Tommy DorseyBest Picture: Rebecca
1950Turned 60
Korean War begins
Gas: $0.27/galHome: $7,354Min wage: $0.75/hrPresident: Harry S. Truman"Goodnight Irene" — Gordon Jenkins & The WeaversBest Picture: All About Eve
1958Died at 68
NASA founded
Gas: $0.31/galHome: $11,050Min wage: $1.00/hrPresident: Dwight D. Eisenhower"Volare" — Domenico ModugnoBest Picture: Gigi
Key Achievements
- Formulated the principle of mass action, showing that memory impairment correlates with the amount of brain tissue removed, not just its location.
- Proposed the concept of equipotentiality, suggesting parts of the cortex can assume functions of damaged areas.
- Authored the influential 1950 paper 'In Search of the Engram,' summarizing his decades-long quest for the physical trace of memory.
- Served as the president of the American Psychological Association in 1929.
Did You Know?
He initially went to West Virginia University to study Latin, but switched to zoology after being inspired by a lecture on Charles Darwin.
His work with brain-lesioned rats was meticulously documented in his 1929 book 'Brain Mechanisms and Intelligence.'
He was a dedicated critic of simplistic behaviorist models, using biological evidence to argue for more complex brain processes.
“This series of experiments has yielded a good bit of information about what and where the memory trace is not. It has discovered nothing directly of the real nature of the engram.”
