Lexical decision task
Encyclopedia
The lexical decision task (LDT) is a procedure used in many psychology
and psycholinguistics
experiments. The basic procedure involves measuring how quickly people classify stimuli as words or nonwords.
Although versions of the task had been used by researchers for a number of years, the term lexical decision task was coined by David E. Meyer
and Roger W. Schvaneveldt, who brought the task to prominence in a series of studies on the structure of semantic memory
in the early 1970s. Since then, the task has been used in thousands of studies, investigating semantic memory and lexical access in general.
s or pseudoword
s (nonsense strings that respect the phonotactic
rules of a language, like trud in English). Their task is to indicate, usually with a button-press, whether the presented stimulus is a word or not.
Lexical decision tasks can measure either, or both the time taken to decide that a string of letters is a word and the time taken to decide that it belongs to a prespecified semantic category . When semantic categories are small and words are related (ex. house - buildings), reaction times appear to be significantly faster than the lexical decision .
The analysis is based on the reaction times (and, secondarily, the error rates) for the various conditions for which the words (or the pseudowords) differ. A very common effect is that of frequency: words that are more frequent are recognized faster. In a cleverly designed experiment, one can draw theoretical inferences from differences like this. For instance, we might conclude that common words have a stronger mental representation
than uncommon words.
Lexical decision tasks are often combined with other experimental techniques, such as priming
, in which the subject is 'primed' with a certain stimulus before the actual lexical decision task has to be performed. In this way, it has been shown that subjects are faster to respond to words when they are first shown a semantically
related prime: participants are faster to confirm "nurse" as a word when it is preceded by "doctor" than when it is preceded by "butter".
Psychology
Psychology is the study of the mind and behavior. Its immediate goal is to understand individuals and groups by both establishing general principles and researching specific cases. For many, the ultimate goal of psychology is to benefit society...
and psycholinguistics
Psycholinguistics
Psycholinguistics or psychology of language is the study of the psychological and neurobiological factors that enable humans to acquire, use, comprehend and produce language. Initial forays into psycholinguistics were largely philosophical ventures, due mainly to a lack of cohesive data on how the...
experiments. The basic procedure involves measuring how quickly people classify stimuli as words or nonwords.
Although versions of the task had been used by researchers for a number of years, the term lexical decision task was coined by David E. Meyer
David E. Meyer
David E. Meyer is a Professor at the University of Michigan, where he is currently the Chair of the Cognition and Cognitive Neuroscience area of the Psychology Department. He received a B.A. in Psychology from Wittenberg University in 1964. He received an M.A. in Mathematics in 1966 and a Ph.D...
and Roger W. Schvaneveldt, who brought the task to prominence in a series of studies on the structure of semantic memory
Semantic memory
Semantic memory refers to the memory of meanings, understandings, and other concept-based knowledge unrelated to specific experiences. The conscious recollection of factual information and general knowledge about the world is generally thought to be independent of context and personal relevance...
in the early 1970s. Since then, the task has been used in thousands of studies, investigating semantic memory and lexical access in general.
The task
Subjects are presented, either visually or auditorily, with a mixture of words and logatomeLogatome
A logatome is an artificial word of one or more syllables which obeys all the phonotactic rules of a language but has no meaning. Examples of English logatomes would be the nonsense words snarp or bluck....
s or pseudoword
Pseudoword
A pseudoword is a unit of speech or text that appears to be an actual word in a certain language , while in fact it is not part of the lexicon. Within linguistics, a pseudoword is defined specifically as respecting the phonotactic restrictions of a language...
s (nonsense strings that respect the phonotactic
Phonotactics
Phonotactics is a branch of phonology that deals with restrictions in a language on the permissible combinations of phonemes...
rules of a language, like trud in English). Their task is to indicate, usually with a button-press, whether the presented stimulus is a word or not.
Lexical decision tasks can measure either, or both the time taken to decide that a string of letters is a word and the time taken to decide that it belongs to a prespecified semantic category . When semantic categories are small and words are related (ex. house - buildings), reaction times appear to be significantly faster than the lexical decision .
The analysis is based on the reaction times (and, secondarily, the error rates) for the various conditions for which the words (or the pseudowords) differ. A very common effect is that of frequency: words that are more frequent are recognized faster. In a cleverly designed experiment, one can draw theoretical inferences from differences like this. For instance, we might conclude that common words have a stronger mental representation
Mental representation
A representation, in philosophy of mind, cognitive psychology, neuroscience, and cognitive science, is a hypothetical internal cognitive symbol that represents external reality, or else a mental process that makes use of such a symbol; "a formal system for making explicit certain entities or types...
than uncommon words.
Lexical decision tasks are often combined with other experimental techniques, such as priming
Priming (psychology)
Priming is an implicit memory effect in which exposure to a stimulus influences a response to a later stimulus. It can occur following perceptual, semantic, or conceptual stimulus repetition...
, in which the subject is 'primed' with a certain stimulus before the actual lexical decision task has to be performed. In this way, it has been shown that subjects are faster to respond to words when they are first shown a semantically
Semantics
Semantics is the study of meaning. It focuses on the relation between signifiers, such as words, phrases, signs and symbols, and what they stand for, their denotata....
related prime: participants are faster to confirm "nurse" as a word when it is preceded by "doctor" than when it is preceded by "butter".