Introduction to Psycholinguistics

Introduction to Psycholinguistics

Y.D. Stephen Lai, Ph.D2011/02

What is psycholinguistics? Language activities take place every day & everywhere…

with great ease in a completely subconscious manner

Because… We understand sentence even though speech streams

include no discrete boundaries to indicate where one word ends and another begins;

We understand speech even faster than we can produce it, and we are so fast that we can even finish each others’ sentences;

Incomplete sentences are no problem for us; We understand stammering non-fluent politicians and non-

native speakers; We deal with ambiguity all the time without breaking down

(computer parsers often maintain thousands of possible interpretations);

We have a vocabulary of about 60,000 words. We access somewhere between 2-4 words/second with low error rates, 2/1000 words (though you may sometimes find it difficult to search a word, i.e., tip of the tongue).

What is psycholinguistics? Can you describe the process underlying

linguistic communication (speaking and comprehending)?

What is psycholinguistics? Language is complex & dynamic

multiple levels of representation & knowledge each level has rich internal structure, unique

constraints & representations processing unfolds over time:

both across levels, and in response to signal levels interact dynamically in complex ways

What is psycholinguistics? Processing: from sound to meaning

What is psycholinguistics? The process of linguistic communication

involves the resolution of uncertainty over a potentially unbounded set of possible signals and meanings. Ambiguity at the word-level: e.g., l-i- [quor]li-quid, li-quor, li-nen, li-sten, li-st, li-ck, li-mb, li-nk Ambiguity at the phrase-level: e.g., red bug eater[red bug] eater vs. red [bug eater] Ambiguity at the sentence-level:e.g., John knows Mary… since he was a child vs. likes cheese

What is psycholinguistics? Issues of importance:

How can a fixed set of knowledge and resources be deployed to manage this uncertainty? And how are the information “represented” in mind? This is the study of language processing

Language processing: a study of how humans comprehend and produce language (sentences, words within sentences, and sequences of sentences, etc.) in real time.

We can divide this into language comprehension (understanding what is spoken and what is written) and language production (choosing what to say or write based on what you want to “mean”)

How can such knowledge and resources be learned from finite input?This is the study of language acquisition.

Language acquisition: a study of how humans acquire knowledge of their native language (as infants and as children)

Dimensions of Psycholinguistics

Level o

f Pro

cessin

g

Depth of Processing

Direction of Processing

Development of processing

Dimensions of Psycholinguistics

What is psycholinguistics? In sum, psycholinguistics can be defined as a

study that explores… Language processing mechanisms and operationsOr The relation between current theories of language

and human linguistic performance

through observational studies, experiments, and computational modeling.

Methods of Psycholinguistic Research:Field technique (observation) Spoonerisms= slips of the tongue

e.g., Feature switching

Segment switching

Intended to be said Actually said

Big and fat Pig and vat

Is Pat a girl? Is bat a curl?

Cedars of Lebanon Cedars of Lemmanon


The dear old queen The queer old dean

Noble sons of toil Noble tons of soil

You have wasted the whole term.

You have tasted the whole worm.

Methods of Psycholinguistic Research:Field technique (naturally occurring)

More examples: Word switching & morpheme switching

What it shows: The entire phrase must be planned in advance, or

else we couldn’t switch segments, morphemes, and words like this. This reveals something about the manner in which sentence (and phrase) production is planned in the mind.

“Morpheme” is the fundamental building component during sentence production.


Rules of word formation Words of rule formation

I’d forgotten about that. I’d forgot aboutten that.

Easily enough Easy enoughly

Methods of Psycholinguistic Research:Field technique (naturally occurring) Tip-of-the-tongue phenomenon:

trying to access a word based on meaning, spelling, initial letter, rhyme, etc.e.g., “Oh, it’s that color that’s really bright green….and it’s also a really strong liquor…but it sounds a bit like “loose”….it starts with a “sh” sounds….chartreuse! That’s it!”

What it shows: How words are organized in the mind = mental

lexicon. Access of the mental lexicon must be very quick, since

word recognition takes just 1/3 of a second

Methods of Psycholinguistic Research: By the way, here are the related questions

regarding the mental lexicon: How are entries in the mental lexicon linked to

each other? How are entries in the mental lexicon accessed? What information is actually contained in an

entry?

Methods of Psycholinguistic Research:Experimental Techniques – Lexical Access Identification task:

A word flashes on a computer screen, and the subject identify what a specified letter/word/color is. Dependent variable (things which are measured):

Response accuracy = whether the subject is correct or not.

Methods of Psycholinguistic Research:Experimental Techniques – Lexical Access Word-superiority effect (Cattell, 1886; Reicher, 1969):

People are more accurate in recognizing a letter in the context of a word than they are when a letter is presented in isolation, or when a letter is presented within a nonword. e.g., FONHGTAEW vs. FOG HAT NEWe.g., WXRK vs. WORK

Task: identify whether the last letter is K or H What it shows:

As our reading experience is accumulated, it is “WORD” rather than “letter string” that is viewed as a basic unit during reading process. Automatic Subconscious (also see Stroop effect:

http://faculty.washington.edu/chudler/java/ready.html) Do you have any explanation?

Methods of Psycholinguistic Research:Experimental Techniques – Lexical Access Rumelhart and McClelland's interactive-

activation model of word recognition

Methods of Psycholinguistic Research:Experimental Techniques – Lexical Access Lexical decision task (LDT):

A word flashes on a computer screen, and the subject indicates whether the word is a real word or a nonsense word by pressing a button labeled ‘YES’ or a button labeled ‘NO’. Dependent variables (things which are measured):

Response latency = how long it takes the subject to decide if the word is a real word (e.g., glove) or a nonsense word (e.g., blove)

Response accuracy = whether the subject is correct or not.

Methods of Psycholinguistic Research:Experimental Techniques – Lexical Access How this relates to the mental lexicon: in

order to decide if a word is a real word or a nonsense word, the mental lexicon must be accessed. Real word: find the mental entry Nonsense word: realize that there is no mental

entry

Methods of Psycholinguistic Research:Experimental Techniques – Lexical Access Frequency effect

e.g., Chinese (Ahrens, 1998): Higher frequency words (mixed with fake words): 讀仰昨天中心專業道特厚測瓦斯味嘩胳瓶給邁找到高興靈禁報案 Lower frequency words (mixed with fake words): 說理美們聲帶文武旅真離世自多動統輕靈醫者實充異同皮盤腐怡 What it shows: more frequent words take less time

(e.g., 專業 or free in English) to access than less frequent words (e.g., 說理 or fret in English). This tells us that some part of the lexicon is organized by individual frequency of the word.

What about “crane” vs. “cliff”? (both share similar familiarity, but one is polysemous)

Methods of Psycholinguistic Research:Experimental Techniques – Lexical Access Priming task

The presentation of one stimulus (PRIME) affects the speed (usually speeding up) of the response to another stimulus (TARGET)"X primes Y" means "X is a prime for Y" or "the presentation of X speeds up (or slows down) the response to Y relative to a control“

Dependent variable: if the prime affects the response latency or not.

Methods of Psycholinguistic Research:Experimental Techniques – Lexical Access Priming effect

e.g., Words prime themselves(prime) book ------ (target) book e.g., Words are primed by morphologically related words (prime) books ------ (target) book; (prime) management ------ (target) manage ? (prime) cancel ------ (target) can e.g., Orthographically related: dock primes for doctor(prime) dock ------ (target) doctore.g., Phonologically related: (prime) worse ------ (target) nursee.g., Words are primed by semantically related words:(prime) bread ------ (target) butter

What does these show?

Methods of Psycholinguistic Research:Experimental Techniques – Lexical Access What it shows:

These all show us ways in which the mental lexicon is organized – by spelling similarity, by phonological similarity, and by constituent morphemes. Thus, there are many different ways to prime for a single entry in the lexicon – suggesting that the entries are linked to each other in several different ways

Methods of Psycholinguistic Research:Experimental Techniques – Lexical Access Other applications:

e.g., Frequency effect again with semantically ambiguous words! Hogaboam and Perfetti (1975):Preceding context (PRIME):(1) The jealous husband read the letter. (2) The antique typewriter was missing a letter.

Task: Is the last word (of a TARGET sentence) ambiguous? Result: Subjects are faster with (2)

What it shows: common (primary) meanings are more rapidly accessed than uncommon (secondary) meanings. In (1), context just reinforces primary meaning; accessing secondary meaning takes longer. In (2), context reminds subjects of the secondary meaning; primary meaning is accessed quickly.

Methods of Psycholinguistic Research:Experimental Techniques – Sentence Processing

Sentence processing: analysis of the meanings of words and analysis of its syntactic structure, an unconscious automatic analysis called as PARSING.

Two commonly adopted methods: Time-reading experiments Eye-movement experiments

Timed-reading Experiment (Self-paced) Assumption: a difficult sentence takes longer to

parse. Therefore, timing how long it takes to process the sentence allows us to rank how “difficult” different sentences are to process.

Bar-pressing paradigm (self-paced reading): The subject reads a sentence one word at a time, and presses the space bar to indicate they have processed that word. One word appears on the screen at a time. `

http://fordyce.inf.ed.ac.uk/users/marai/index-reading.html

The pattern of how long it takes to process a word reflects the semantic and syntactic structure of the sentence. Content words take longer to process than function words.

(semantic) Subjects pause at the end of clause boundaries. (syntactic)

Boland’s (1997) e.g., Boland (1997): examination of influence of

discourse context and probabilistic factors in the initial assignment of syntactic category Unambiguous possessive pronoun, nounShe saw his duck and chickens near the barn. Unambiguous accusative pronoun, verbShe saw him duck and stumble near the barn.

Boland’s (1997) Context (you can imagine it as a PRIME):

Context bias toward possessive pronoun, nounAs they walked around, Kate looked at all of Jimmy’s pets. Context bias toward accusative pronoun, verbAs they walked around, Kate watched everything that Jimmy

did. What’s your prediction?

If discourse context influences the initial assignment of syntactic category, RTs for the pronoun his ought to be faster when the discourse context is biased toward the possessive, and RTs for him ought to be faster when it is biased toward the accusative.

If frequency of use of the noun vs. verb meanings of the homograph, RTs in possessive contexts should decrease as the noun meaning increases in frequency.

Boland’s (1997) Results:

Discourse context did not have a significant effect on RTs on any word.

Completion that favors a noun usage for the homograph in “she saw her duck…” is related to RTs for the word “and”.

Eye-movement experiments Reading involves eye movements of a subject.

So, experiments can be done with eye-tracking.

Eye-movement experiments



Eye-movement experiments Things to be measured:

Fixation Saccade

Eye-movement experiments Fixation:

Eye is a (relatively) still and “fixated” to the certain point, e.g., reading a single word.

All the information from the scene is (mainly) acquired during fixation.

Duration varies from 120-1000 ms, typically 200-600 ms.

They are Interspersed with saccades...

Eye-movement experiments Saccade:

“Jumps” which connect fixations Very rapid -- duration is typically only 40-120

ms Very fast (up to 600 o/s) and therefore the

vision system is suppressed during the movement

Ballistic; the end point of saccade cannot be changed during the movement

Saccades are used to move the fixation point Why measure the two behaviors?

Eye-movement experiments Because when readers encounter processing

difficulty, one reader may fixate on the problematic region

until the difficulty is attenuated; one may also move his/her eyes to the regions

prior the current problematic area (regressive saccades);

one may move his/her eyes to the regions that follow the current area.

Assumption: The eye movements reflect processing. Thus, longer fixations and backwards movements reflect processing difficulty.

Eye-movement experiments Subjects tend to fixate on content words. Subjects’ eyes move backwards in the sentence when a

mis-parse occurs. Syntactically complex and semantically anomalous bits

of sentences tend to create lots of backwards movements. syntactically complex: “The defendant examined by the

lawyer…” = The defendant who was examined by the lawyer semantic anomalous: “I like my coffee with cream and

socks.”While Mary was mending the sock fell off * * * * * * * * * 1 2 3 6 4 7 5 8 9 (order of fixation) 277 213 233 277 445 289 (fixation time)

401 233 314

Brain activity: ERPs We can measure electrical activity in the brain

when a subject is reading a sentence Reflect electrical activity of bundles of cortical

neurons Standard effects: N400, P600

Typical peak time, polarity N400 = negative voltage change

approximately 400ms after a word is read which is semantically odd.

P600 = positive voltage change approximately 600ms after a word is read which is syntactically odd.

Brain activity: ERPs e.g. for N400, “The pizza was too hot to

cry/eat.”

e.g. for P600, “Sarah’s belief in fairies vs. Sarah’s in belief fairies”

Brain activity: ERPs The cat will EAT/BAKE. ?

The cat will EAT/EATING. ?

a. b.

Brain activity: ERPs What this means: processing of sentences is

immediate and “online” – happens as each word is read, rather than waiting until the end of a sentence/clause/phrase to put things together.

Linguistics and Language Processing: Bottom-up and Top-down Models Language comprehension involves a lot of

work… Segmentation, lexical access (looking up

words/morphemes in the mental lexicon & finding the appropriate meanings of ambiguous words,) syntactic parse (disambiguating syntactic ambiguity)…etc.

What it shows: fast, automatic, robust, accurate disambiguation, “guess”…

Sentence comprehension involves top-down & bottom-up processing.

Bottom-up and Top-down Models Top-down: beginning interpretation of a

sentence spontaneously and automatically based on what information is available to us. For instance, we do not have to wait until we have analyzed all the phonemes in a sentence in order to understand it.

Bottom-up: doing step-by-step analysis to isolate phonemes, word boundaries, and relate these things to the mental lexicon and semantic interpretation. It happens only piece by piece – no forward projection, no prediction.

Bottom-up and Top-down Models Comparison:

Hoggle fell gracelessly to the ground. Top-down processing: prime only for soil Bottom-up processing: prime for soil and grind

A person using very strong top-down processing would only be primed for the meaning which is appropriate, given the syntactic structure. A person using very strong bottom-up processing would be primed for both meanings, despite the fact that only one meaning is appropriate.

Top-down Models The pweor of the hmuan mnid. Aoccdrnig to

rscheearch codnutced at Cmabrigde Uinervtisy, it deosn't mttaer in waht oredr the ltteers in a wrod are tpyed, the olny iprmoetnt tihng is taht the frist and lsat ltteer be in the rghit oedrer. The rset can be a tatol mses and you can sitll raed it wouthit porbelm. Tihs is bcuseae the huamn mnid deos not raed ervey lteter by istlef, but the wrod as a wlohe. Amzanig huh? So yuo raed tihs wuothit mcuh porbelm, tpyos shohlud not be a porbelm aynmroe.

Top-down Models Some evidence for top-down processing

Better performance in identification task of spoken words in the presence of noise when they occur in sentences than in isolation/ anomalous/ non-sense sentences.

Shadowing Phoneme restoration

e.g., “The state governors met with their respective legi X(cough) latures convening in the capital city.

Role of context in segmentatione.g., [g r e d e] --- Grade A [quality of meat /eggs]

--- grey day [weather]

Top-down Models Comprehenders do not wait until the whole

sentence has been heard to make inferences about what it means or will wind up meaning: The onset of saccadic eye movements to the

target object (the cake) was significantly later in the move condition than in the eat condition;

Saccades to the target were launched after the onset of the spoken word cake in the move condition, but before its onset in the eat condition.

Top-down Models Try to guess the next word in the sentence

My brother came inside to. . . chat? get warm? talk? eat? rest?

The children went outside to. . . play

Empirically, it’s been shown that more highly predictable words are read more quickly (Ehrlich and Rayner, 1981)

Phonetics & Phoneme Features (as associated with bottom-up

processing)

Phonemes Cohort Model :William Marslen-Wilson

proposed that in word comprehension, words are recognized from beginning to end.


Big and fat Pig and vat

Is Pat a girl? Is bat a curl?

Cedars of Lebanon Cedars of Lemmanon

Phonetics & Phonemee.g., hearing “crystal”. = [krIstal]. First, we

process the [k], and initially consider all the words that begin with [k]. All the words considered are called the cohort. Then we process the [r], and consider all the words that begin with [kr]. (The cohort is reduced from all the words that begin with [k] to all the words that begin with [kr]).

And so on, until we process all the segments of “crystal”.

Shown with experiments that this is the case. Suggests that the segment is a fundamental unit of

auditory perception.

Phonetics & Phoneme Syllables

Syllables used successfully as primes in lexical decision tasks.

Word-blending tasks: subjects unconsciously split words at natural points in the syllablethe onset vs. the rhyme.e.g., “bark” + “meow” = ? “beow” (rather than “baow”)e.g., “but” + “cat” = “bat” (rather than “but”)

Subjects prefer to create word blends according to the syllable structure of their language.

Morphological processing Morpheme activation

Do individual morphological components of words play a role in processing? Individual morphemes in compound words are

automatically activated during word recognition. Evidence: crowbar primes bird.

Selectional restrictions Do knowledge of selectional restrictions play a role

in processing new words? e.g., *understand-ize Knowledge of the restrictions of affixes forms part of the

word-processing system Evidence: (note: birm is a non-sense word) re-birmable vs. re-birmize, vs. re-birmity RT: longer

Morphological processing Hierarchical structure

Our representation of complex words is organized in terms of hierarchical morphological structure.

Please draw the tree structures for “refillable” and “unbearable”

Evidence: a. PRIME “bearable” ---- TARGET “unbearable”b. PRIME “fillable” ------- TARGET “refillable” Larger priming for… (a)

Syntactic Processing Some grammatically complex sentences are easy

to parse and some grammatically easy sentences are hard to parse. e.g., (complex sentence but easy parsing)

Sarah saw the goblin who displeased Jareth the other day.

e.g., (easy sentence but hard parsing)The horse raced past the barn fell.

e.g., (which one is easier?)a. This is the malt that the rat that the cat that the dog worried killed ate. b. This is the malt that was eaten by the rat that was killed by the cat that was worried by the dog.

Garden-path sentences: those that lead one down the garden path to the wrong analysis. The horse raced past the barn fell. The girl told the story cried. Since Jay always walks a mile seems like a short

distance to him.

Syntactic parser: a special processing module that makes use of grammatical knowledge but also contains special procedures and principles that guide the order in which elements of a sentence are processed and the manner in which syntactic structure is built up.

These are just tips of the iceberg …More to be read, discussed, and

explored! Are you ready to take this course?

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Introduction to Psycholinguistics