Karl Lashley

Infobox Scientist
name = Karl Spencer Lashley
box_width =


image_width =150px
caption = Karl Spencer Lashley
birth_date = June 7, 1890
birth_place = Davis, West Virginia
death_date = August 7, 1958
death_place =
residence =
citizenship =
nationality = United States
ethnicity =
field = psychology
work_institutions =
alma_mater = Johns Hopkins University
doctoral_advisor =
doctoral_students =
known_for = learning and memory
author_abbrev_bot =
author_abbrev_zoo =
influences =
influenced =
prizes =
religion =
footnotes =

Karl Spencer Lashley (1890–1958), born in Davis, West Virginia, was an American psychologist and behaviorist well-remembered for his influential contributions to the study of learning and memory. His failure to find a single biological locus of memory (or "engram", as he called it) suggested to him that memories were not localized to one part of the brain, but were widely distributed throughout the cortex.

While working toward his Ph.D. in genetics at Johns Hopkins University, Karl Lashley became associated with the influential psychologist John B. Watson. During three years of postdoctoral work on vertebrate behavior (1914-17), he began formulating the research program that was to occupy the remainder of his life.

In 1920 he became an assistant professor of psychology at the University of Minnesota, Minneapolis, where his prolific research on brain function gained him a professorship in 1924. He was later a professor at the University of Chicago (1929-35) and Harvard University (1935-55) and also served as director of the Yerkes Laboratories of Primate Biology, Orange Park, Florida from 1942 to 1955.

His work included research on brain mechanisms related to sense receptors and on the cortical basis of motor activities. His major work was done on the measurement of behavior before and after specific, carefully quantified, induced cortical damage in rats. He trained rats to perform specific tasks (seeking a food reward), then lesioned varying portions of the rat cortex, either before or after the animals received the training depending upon the experiment. The amount of cortical tissue removed had specific effects on acquisition and retention of knowledge, but the location of the removed cortex had no effect on the rats' performance in the maze. This led Lashley to conclude that memories are not localized but widely distributed across the cortex.Today we know that distribution of engrams does in fact exist, however, the distribution is not equal across all cortical areas, as Lashley assumed. His study of the V1 (primary visual cortex) led him to believe that it was a site of learning and memory storage (i.e an engram) in the brain. He reached this erroneous conclusion due to imperfect lesioning methods.

By 1950, Lashley had distilled his research into two theories. The principle of "mass action" stated that the cerebral cortex acts as one—as a whole—in many types of learning. The principle of "equipotentiality" stated that if certain parts of the brain are damaged, other parts of the brain may take on the role of the damaged portion.

Notable publications

*1923 "The behavioristic interpretation of consciousness." "Psychological Bulletin"
*1929 "Brain mechanisms and intelligence."
*1930 "Basic neural mechanisms in behavior." "Psychological Review"
*1932 "Studies in the dynamics of behavior." University of Chicago Press.
*1935 "The mechanism of vision", Part 12: Nervous structures concerned in the acquisition and retention of habits based on reactions to light. "Comparative Psychology Monographs" 11: 43–79.
*1950 "In search of the engram." "Society of Experimental Biology" Symposium 4: 454–482.
*1951 "The problem of serial order in behavior." "Cerebral Mechanisms in Behavior"

References

*Citation
id = PMID:12115784
url= http://www.ncbi.nlm.nih.gov/pubmed/12115784
id = PMID:12115785
url= http://www.ncbi.nlm.nih.gov/pubmed/12115785
last=Dewsbury
first=Donald A
publication-date=2002
year=2002
title=Constructing representations of Karl Spencer Lashley.
volume=38
issue=3
periodical=Journal of the history of the behavioral sciences
pages=225-45
doi = 10.1002/jhbs.10060
*Citation
id = PMID:11894885
url= http://www.ncbi.nlm.nih.gov/pubmed/11894885
last=Dewsbury
first=D A
publication-date=2002 Feb
year=2002
title=The Chicago Five: a family group of integrative psychobiologists.
volume=5
issue=1
periodical=History of psychology
pages=16-37
*Citation
id = PMID:10693270
url= http://www.ncbi.nlm.nih.gov/pubmed/10693270
last=Sapetskiĭ
first=A O
publication-date=
year=
title= [A physiologist's dialog with a psychologist]
volume=49
issue=6
periodical=Zhurnal vyssheĭ nervnoĭ deiatelnosti imeni I P Pavlova
pages=909-18
*Citation
id = PMID:3511136
url= http://www.ncbi.nlm.nih.gov/pubmed/3511136
last=Bruce
first=D
publication-date=1986 Jan
year=1986
title=Lashley's shift from bacteriology to neuropsychology, 1910-1917, and the influence of Jennings, Watson, and Franz.
volume=22
issue=1
periodical=Journal of the history of the behavioral sciences
pages=27-44
*Citation
id = PMID:4941968
url= http://www.ncbi.nlm.nih.gov/pubmed/4941968
last=Roofe
first=P G
publication-date=1970 Jan
year=1970
title=Some letters from the Herrick-Lashley correspondence.
volume=8
issue=1
periodical=Neuropsychologia
pages=3-12
*Citation
id = PMID:13658968
url= http://www.ncbi.nlm.nih.gov/pubmed/13658968
last=CARMICHAEL
first=L
publication-date=1959 May 22
year=1959
title=Karl Spencer Lashley, experimental psychologist.
volume=129
issue=3360
periodical=Science
pages=1410-2
*Citation
id = PMID:13590401
url= http://www.ncbi.nlm.nih.gov/pubmed/13590401
last=WALSHE
first=F M
publication-date=1958 Nov
year=1958
title=Karl S. Lashley.
volume=8
issue=11
periodical=Neurology
pages=870
*Citation
id = PMID:12115785
url= http://www.ncbi.nlm.nih.gov/pubmed/12115785
id = PMID:12115784
url= http://www.ncbi.nlm.nih.gov/pubmed/12115784
last=Weidman
first=Nadine
publication-date=2002
year=2002
title=The depoliticization of Karl Lashley: A response to Dewsbury.
volume=38
issue=3
periodical=Journal of the history of the behavioral sciences
pages=247-53; discussion 255-7
doi = 10.1002/jhbs.10061

ee also

*Sequence learning
*Engram (neuropsychology)
* [http://www.gfai.de/~heinz/publications/lectures/2007_kreuth_abstract.htm Holographic properties found in interference networks]