Psycholinguistics: Lexical Processing PDF

Psycholinguistics Part 7 Lexical Processing 1 What is lexical processing?  It refers to the way the words are stored and recognized. 2  The ability to recognize words is remarkable;  People can recognize words extre...

Psycholinguistics Part 7 Lexical Processing 1 What is lexical processing?  It refers to the way the words are stored and recognized. 2  The ability to recognize words is remarkable;  People can recognize words extremely quickly.  Even though an average college-educated adult knows between 40,000 and 60,000 words, it takes about 250 milliseconds to find a word in the mental lexicon.  Finding a word in the mental lexicon is hard as many of the words in the lexicon are similar in that many of these words are constructed from a small number of phonemes, like star, stare, start, stop, step, tar, etc. 3 In this Presentation, we will discuss: 1. How words are stored in the mental lexicon. 2. The process of word recognition. 3. What word recognition tells about the organization of the mental lexicon. 4 1. The Mental Lexicon  It is a dictionary located in Wernicke’s area in the brain, which contains all the words an individual knows, including: The meaning of the words, The pronunciation of the words, How a word is used in conjunction with other words, And other information about the individual words, like its plural form if it is a noun, the past tense form if it is a verb, and so on. 5 Question:  Are complex words, like globalization, internationalization, and generalization, stored as whole words or are broken up into morphemes in the mental lexicon? 6 To answer this question,  Three hypotheses were presented: 1. The full listing hypothesis. 2. The affix-stripping hypothesis. 3. A combination of the two hypotheses (1+2). 7 1. The Full Listing Hypothesis  In this case, each of the complex words would be stored as a separate entry, so each of the following words is an individual entry: - globe, global, globalize, globalization, - nation, national, nationalize, international, internationalize, nationalization, internationalization, 8 The Strength of this hypothesis: - Storing every word individually allows for fast access. The weaknesses of this hypothesis: - Storing words individually takes up a lot of storage space. - The generalization that these words are in some way are related to each other is missed 9 2. The Affix-Stripping Hypothesis  Here, complex words are broken down into morphemes, with each morpheme stored individually in the mental lexicon.  For example, globalization and internationalization are built from the following entries: globe nation -al, -ize, -ation, inter- 10 The Strengths of this hypothesis:  Storing only morphemes would reduce the - number of entries in the lexicon. - storage space.  Breaking down words into morphemes would highlight the nature of the relationship between words. 11 The weakness of this hypothesis:  Lexical access would be slowed down since words would be decomposed into and rebuilt from individual morphemes during comprehension and production. 12 3. A combination of the two hypotheses (1+2).  More recent models propose that the truth lies somewhere in between; some complex words may be stored as whole units , while others may be stored decomposed.  The degree of decomposition depends on the kinds of affixes a complex word contains. 13  Some affixes are transparent, attaching them to a root does not change the way the root is pronounced and the meaning of the complex word is compositional;  For example, the affix –er ‘a person who does X, where X is a verb’, which can be attached to verbs like write and read to create the words writer ‘a person who writes’ and reader ‘a person who reads. 14  Other affixes are not as easily decomposed since attaching them to a root frequently changes the way the root is pronounced;  For example, when we attach –ation to derive, the pronunciation of the second vowel changes from [aɪ] to [ɪ], giving derivation. Decomposing words with such affixes is not straighforward since the meaning is not always obvious from the parts. 15  Thus, it is possible that a word like derivation is stored as one unit, while writer is decomposed and stored as two elements.  Importantly, while there is experimental support to this hypothesis, more research is needed to understand which affixes are stored in the lexicon separately and which are not. 16 2. The Process of Word Recognition  One common-sense view of how word recognition takes place is ‘the cohort model’.  In this model, as soon people hear speech, they start narrowing down the possible words they may be hearing.  If the first sound that they hear is /s/, all words beginning with any other sound are eliminated. 17  If the next sound is /k/, many other possible words are ruled out, like sport, summer, snake, etc.  A word is identified as soon as there is only one possibility left. This is called the uniqueness point of a word.  The word ‘cohort’ refers to all the words that remain on the list of possible words as the auditory input progresses. 18  Experimental Support to this Model: - Recognition becomes more difficult, perhaps impossible, when the initial sound of a word is mispronounced than when the final sound is mispronounced. 19  Problems of this Model; - In listening to running speech, people can’t always identify where a word starts. In some cases word boundaries are not clear, so people may not be able to know the initial sounds. -I scream -ice cream -a name -an aim Thus, how does word recognition take place? 20 Factors that Affect Word- Recognition: 1. The Frequency Effect:  Words that occur more frequently (like water, TV, laptop) are easier to access than words that occur less often (like mortgage, obituary, disinfect). - To explain such effect, it is hypothesized that the lexicon is partially organized by frequency. 21 2. Recency Effect:  People recognize a word faster when they have just heard or read it than when they have not recently encountered it 22 3. Context Effects  People recognize a word easier when the preceding words provide an appropriate context for it. For example, - In the sentence This is the aorta, people are not given any context that helps to identify the word the aorta. 23  - But in the sentence The heart surgeon carefully cut into the wall of the right aorta, the words heart surgeon help people to identify the word aorta more quickly. 24 Lexical Ambiguity:  Lexical ambiguity means that a single word can be the form of two or more lexical expressions that differ in meaning, or syntactic properties, or both.  Examples: right: opposite of ‘left’ opposite of ‘wrong’ 25 Think: Is the word ‘marry’ lexically ambiguous? - Jack married Sarah. - The priest married them. 26 There are two theories of how lexical ambiguity is resolved: 1. The first theory claims that all the meanings associated with the word are accessed, with the correct meaning eventually being selected. 2. The second theory claims only one meaning is accessed initially and the listener holds on to this meaning until finding evidence that confirms or contradicts the first assumption. 27 Support to the first theory:  When people are asked to finish a sentence, they take longer when the fragment to be finished contains an ambiguous word. 1. After taking the right turn at the intersection… 2. After taking the left turn at the intersection.. 28 Support to the second theory:  If a word is associated with more than one meaning and one of the meanings is more frequent than the other, people tend to assign the more frequent meaning to the word. 29 Example:  The word “chair” has two meanings: 1. ‘An object to sit on’ 2. ‘The head of a department or a committee’  It has been found that when people hear the word chair, they tend to associate it with the first meaning as it is the more frequent meaning. 30 31