Characteristics of human languages

• Language is creative
  • Open class vs. Closed class words
  • Recursion: The set of possible sentences in any language is infinite.

• Language is also constrained.
  Consider how verbs are sometimes created from nouns

  Julia summered in Paris.
  Kent wintered in Mexico.
  Martine holidayed in France.
  They honeymooned in Hawaii.
  

  Jerome midnighted in the streets*
  Andrea nooned at the restaurant*
  Philip one o'clocked at the airport*
  

  The first set seems acceptable but the second set doesn't. But why?

  **The fact that language is constrained is what allows for its creativity.

Language is Symbolic

Language can be described at several levels.

• Phonetics: Phonetics involves the production of and perception of speech sounds. The study of differences between speech sounds.
• Phonology: Phonology involves the patterning of speech sounds. The study of which differences matter.
  • Allophones: Allophones are differing speech sounds which are treated as if they were identical by a speech community.
• Morphology: The study of word formation.
  • Lexeme: A word
  • Morpheme: A unit of meaning in a word.
  A lexeme is made up of one or more morpheme's
• Syntax: Formation of sentences
• Semantics: Study of meaning, interpretation of words and sentences.
• Pragmatics: The uses to which language is put and the shared assumptions that speakers and listener's share.

Word Recognition

• Logogen model (Morton, 1969, etc)
  • logogen = adding device for each word. It accumulates evidence until the amount of evidence for that word exceeds a threshold, causing the word to be recognized.
  • uses a signal detection model for each logogen
  • context and stimulus information increase a logogen's resting activation
  • word frequency changes the logogen's threshold
  • activation only; no inhibition

• Interactive activation model (McClelland & Rumelhart, 1981)
  • Connectionist model of letter and word recognition
  • a node for each feature; a node for each letter; a node for each word
  • Key differences from the logogen model: Both excitatory and inhibitory connections
  • Activation of one word causes a decrease in activation of all the other words
  • structure not defined before-hand: all letter nodes are connected to all word nodes, not just the letters in a particular word. The connection weights between nodes are changed during the learning (or "training") stage.
  • Parallel, interactive processing: Not serial processing (first recognize the letters, then recognize the word by which letters it has),
  • The interactive activation model uses parallel processing -- activation passes among all the nodes at once, so activation of the word nodes can affect what happens to the letter nodes. (This illustrates the general point that connectionist models tend to predict interactions between different levels of processing.)

Syntax

• Syntax is a set of rules and categories which allow sentences to be formed and interpreted.
• Syntactic rules: Syntactic rules are rules for how to create the set of possible sentences in a language. These rules define the set of grammatically acceptable sentences. The sentences may be unacceptable for other reasons. Linguists assume that these rules describe language NOT that people explicitly apply these rules
  Sentence = Noun Phrase + Verb Phrase

  Noun Phrase = (Determiner) +(Adjective Phrase)+ Noun+ (Prepositional Phrase)

  Verb Phrase = Verb + (Noun Phrase) + (Prepositional Phrase)

  Etc.

  **Note these are just examples of what syntactic rules look like. You needn't memorize them

• Parsing: Interpreting a sentence in terms of phrase structure rules is called parsing the sentence.

• Syntactic ambiguity: A sentence is syntactically ambiguous when there is more than one way to parse it.
  Sam hit the dog with the stick.

• Syntactic ambiguity cannot be resolved by appealing to purely syntactic factors. Must consider semantics and pragmatics to resolve.
  Sam shot the dog with the gun.

• This sentence is syntactically ambiguous, yet its interpretation is obvious since dogs typically do not carry guns.

Semantics

• Truth functional semantics: According to this view, we understand the meaning of a sentence when we are able to specify that conditions which would have to exist in order for that sentence to be true.
• Referential semantics: According to this account the meaning of a word is giving by the things it refers to in the world, or its extension. The word dog is meaningful in that it picks out the set of dogs that exists in the world.
  The morning star is the evening star
  Words exist for imaginary objects like unicorns
  

• Semantic decompostion: According to this theory, meaning is derived by decomposing sentences into words and words into semantic features.
  Bachelor = Male, Adult, Never married

• Relational Accounts: Word meaning is a function of the word's relationship to other words.

Pragmatics

• Performatives: Statements which accomplish something by virtue of being uttered.

  Get me a beer.

• Constatives: Statements which describe states of affairs.
  There is beer in the fridge.

• Many linguists believe that all statements are really performatives
• Performatives can be direct or indirect

  Could you turn the heat up?
  Sure is cold in here
  Turn up the heat
  

• So how do we know when a statement is direct and when it is indirect?

• Gricean Maxims: Grice's maxims are rules that people assume in conversations unless there is evidence to the contrary. They are provisional assumptions used to interpret utterances.
  • Maxim of quantity: Utterances will be as informative as necessary but not more so.
  • Maxim of Quality: Utterances will convey what the speaker believes to be true based on adequate evidence.
  • Maxim of relation: Utterances will be relevant to the ongoing conversation
  • Maxim of manner: Utterances will avoid obscurity, ambiguity, and wordiness.
    Example:

    Let's say its John's turn to wash the dishes, but he forgets to do it. Later Mary washes the dishes in view of John. Once she's done she say's, "Well, (heavy sigh) I washed the dishes."

    Mike says to Matt, "Hey let's have the guys over and play poker tonight." Matt replied, "I have a quiz in Lampinen's class tommorow."

Context and Language Comprehension

• Prior knowledge and comprehension

  • This story makes sense to most people
    John went to a restaurant. He asked the waitress for a cheeseburger. He paid the check and left.

  • This story makes sense to few people
    John went to the park. He asked the midget for a mouse. He picked up the box and left.

• Prior Knowledge is important for comprehension(Bransford & Johnson, 1973)
  The procedure is actually quite simple. First you arrange things into different groups depending on their makeup. Of course, one pile may be sufficient depending on how much there is to do. If you have to go somewhere else due to lack of facilities that is the next step, otherwise you are pretty well set. It is important not to overdo any particular endeavor. That is, it is better to do too few things at once than too many. In the short run this may not seem important, but complications can be expensive as well. The manipulation of the appropriate mechanisms should be self-explanatory and we need not dwell on it here. At first the whole procedure will seem complicated. Soon, however, it will become just another facet of life. It is difficult to foresee any end to the necessity for this task in the immediate future, but then one never can tell.
  • Participants given prior knowledge rated this story as easier to understand and also remembered more of it.

• Prior context and resolution of ambiguity
  • Swinney & Hakes(1976)

    Ambiguous: Rumor had it that, for years, the government building had been plagued with problems. The man was not surprised when he found several bugs in the corner of his room.

    Control: Rumor had it that, for years, the government building had been plagued with problems. The man was not surprised when he found several insects in the corner of his room.

    • Subjects performed a phoneme monitoring task while they listened to sentences like these. The phoneme monitoring task required them to press a button as soon as they heard a word beginning with a particular letter (in this case "c").
    • The phoneme monitoring task should be more difficult if someone is confused by an ambiguous word.
    • The time taken to press the button after hearing the word corner was greater for the ambiguous sentence than for the control sentence.

  • What happens if the prior context is consistent with only one of the meanings? Swinney (1979).

    Compared cases where meaning is clear from prior context with cases where meaning is clear from word itself.

    Control: Rumor had it that, for years, the government building had been plagued with problems. The man was not surprised when he found several insects in the corner of his room.

    Ambiguous word in a context that makes meaning clear: Rumor had it that, for years, the government building had been plagued with problems. The man was not surprised when he found several spiders, roaches and other bugs in the corner of his room.

    • Question: When you hear the word "bug" do you consider both meanings or only the one that makes sense given the context?
    • Subjects listened to these sentences while performing a LEXICAL DECISION TASK.
      --SPY (related to the inappropriate meaning)
      --ANT (related to the appropriate meaning)
      --CAR (related to neither meaning)

    • The theory is that if you can correctly identify that something is a word, then that concept must have become active in memory. So for instance if you can quickly respond to the word SPY it means that you must have been thinking about spies.
    • If the prime was presented immediately after the ambiguous word, then both SPY and ANT were responded to more quickly than normal. This indicates that both senses of the word bug were temporarily activated.
    • If the prime was presented 750 msec after the ambiguous word, then only the contextually appropriate word ANT was responded to more quickly than normal

The Kintsch-Van Dijk Model of text comprehension

• How do people process information as they are reading or listening
• Components of the model
  • Short term memory
  • Long Term memory
  • Propositions
• How is information processed
  • Propositions enter STM and are connected to other propositions through argument repetition
  • Some propositions leave STM and enter LTM. New propositions enter STM and are connected to propositions which are already there.
  • If new propositions cannot be connected to any propositions already in STM a re-instatement search occurs. This means that information in LTM must be found to connect the new propositions to.
  • This process is repeated until the entire text enters LTM. Each time information enters STM to be connected with old information it is called a "Cycle"
• Predictions and evidence
  • Re-instatement searches should make reading difficult
  • Propositions which remain active in STM the longest are the ones which should be most likely to be retrieved.

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