- Stroop effect
psychology, the Stroop effect is a demonstration of interference in the reaction timeof a task. When a word such as blue, green, red, etc. is printed in a colordiffering from the color expressed by the word's semanticmeaning (e.g. the word "red" printed in blue ink), a delay occurs in the processing of the word's color, leading to slower test reaction times and an increase in mistakes. The effect is named after John Ridley Stroopwho first published the effect in English in 1935.cite journal
title=Studies of interference in serial verbal reactions
journal=Journal of Experimental Psychology
The effect had previously been published in 1929, but only in German. [Jaensch, E. R. (1929). "Grundformen menschlichen Seins." Berlin: Otto Elsner.] cite journal
author=Jensen AR, Rohwer WD
title=The Stroop color-word test: a review
url=] cite journal
title=Half a century of research on the Stroop effect: an integrative review
url=http://content.apa.org/journals/bul/109/2/163] The original paper has been one of the most cited papers in the history of
experimental psychology, leading to over 710 replications.
In his experiment, J. Ridley Stroop administered several
variations of two main tests. Stroop referred to his tests as RCN, to stand for "Reading Color Names", where participants were required to repeat the written meaning of words with differing colored fonts, and NCW, to stand for "Naming Colored Words", in which participants were asked to orally identify the color of each printed color name. Additionally Stroop tested his participants at different stages of practice with each task, to account for the effects of association.
Stroop identified a large increase on the time taken by participants to complete the NCW (Naming Colored Words) tasks, an effect still pronounced despite continued practice at each task. This interference was explained by the automation of reading, where the mind automatically determines the
semanticmeaning of the word, and then must override this first impression with the identification of the color of the word, a process which is not automatized.
Since its development, the Stroop task, a measure of the effect of interference on performance of a color identification task, has utilized the Stroop effect to investigate aspects of such varied psychological disorders as
Attention Deficit Hyperactivity Disorder, Schizophrenia, and Anorexia. EEGand fMRIstudies of the Stroop effect have revealed selective activation of the anterior cingulate cortexduring a stroop task, a prefrontal structure (see frontal lobe) in the brain which is hypothesized to be responsible for conflict monitoring.
Further development and usage
Edith Kaplan's group (developer of the Delis-Kaplan neuropsychological testbattery) developed the task further by separating the task into four different stages: naming color fields, congruent color words, incongruent color words, and combined. The additional strain on the executive functionof the brainallows for a more precise diagnosis.Fact|date=October 2008
The Stroop task is also employed to study frontal function and
attentionin brain imaging studies.cite journal
author=Pujol J, Vendrell P, Deus J, "et al"
title=The effect of medial frontal and posterior parietal demyelinating lesions on stroop interference
url=] Speaking is not possible in the scanner because it moves the head, so a number theme is often used instead. For instance, "three words" may be displayed that read "two" and the participant must press "three" on their button box.cite journal
author=Kaufmann L, Ischebeck A, Weiss E, "et al"
title=An fMRI study of the numerical Stroop task in individuals with and without minimal cognitive impairment
journal=Cortex; a journal devoted to the study of the nervous system and behavior
The test has additionally been modified to include other sensory modalities and variables,cite journal
author=Roberts KL, Hall DA
title=Examining a supramodal network for conflict processing: a systematic review and novel functional magnetic resonance imaging data for related visual and auditory stroop tasks
journal=Journal of cognitive neuroscience
url=] to study the effect of bilinguislism,cite journal
author=Rosselli M, Ardila A, Santisi MN, "et al"
title=Stroop effect in Spanish-English bilinguals
journal=Journal of the International Neuropsychological Society : JINS
url=] or to investigate the effect of emotions on interference.cite journal
author=Kampman M, Keijsers GP, Verbraak MJ, Näring G, Hoogduin CA
title=The emotional Stroop: a comparison of panic disorder patients, obsessive-compulsive patients, and normal controls, in two experiments
journal=Journal of anxiety disorders
url=] A similar effect has also been observed in individuals with
grapheme-color synesthesia- people who perceive colors when seeing certain numbers and letters. If a number or letter is presented to such an individual in a color other than what they would perceive, there is a delay in determining what color the character actually is. [Ramachandran, V.S. and Edward M. Hubbard. " [http://www.sciam.com/article.cfm?articleID=000C1460-6681-1E94-8EA5809EC5880000&pageNumber=1&catID=9 More Common Questions about Synesthesia] . "Scientific American" online. April 14, 2003. URL accessed 2007-03-12.]
troop effect in popular culture
The "" software program, produced by
Ryūta Kawashimafor the Nintendo DSportable video gamesystem, contains an automated Stroop Test administrator module, translated into game form.
A "Nova" episode used the Stroop Effect to illustrate the subtle changes of the mental flexibility of Mt. Everest climbers in relation to altitude.cite web |url=http://www.pbs.org/wgbh/nova/everest/exposure/braintest.html |title=NOVA Online | Everest | Test Your Brain |format= |work= |accessdate=]
John Ridley Stroop, " [http://psychclassics.yorku.ca/Stroop/ Studies of interference in serial verbal reactions] " from " [http://psychclassics.yorku.ca/ Classics in the History of Psychology] ".
* [http://www.apa.org/science/stroop.html Demonstration and definition of the Stroop effect.]
* [http://www2.b3ta.com/clickthecolour/ Online game based on Stroop effect] .
* [http://www.whatthefreek.com/stroop Interactive Flash Demo of Stroop Effect.]
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