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Dependency Locality Theory Vera Demberg Computational Psycholinguistics Universität des Saarlandes WS 2014/2015 Dec 8th, 2014 Vera Demberg (UdS) Dependency Locality Theory Dec 8th, 2014 1 / 12

Dependency Locality Theory Examples of difficult sentences Which one is more difficult? a) The reporter who attacked the senator disliked the editor. b) The reporter who the senator attacked disliked the editor. Observations: a) seems easier. a) is a subject relative clause while b) is an object relative clause a) and b) differ in syntactic structures, in particular dependencies. Which one is more difficult? a) The reporter who everyone that I met trusts disliked the editor. b) The reporter who the senator who John met attacked disliked the editor. Observations: a) is easier. the difference lies only in the presence of new discourse referents. Vera Demberg (UdS) Dependency Locality Theory Dec 8th, 2014 2 / 12

Dependency Locality Theory Examples of difficult sentences Which one is more difficult? a) The reporter who attacked the senator who hates my dog disliked the editor. b) The reporter who the senator who my dog hates attacked disliked the editor. Observations: a) seems easier. a) is a subject relative clause while b) is an object relative clause a) and b) differ in syntactic structures, in particular dependencies. Which one is more difficult? a) The reporter who everyone that I met trusts disliked the editor. b) The reporter who the senator who John met attacked disliked the editor. Observations: a) is easier. the difference lies only in the presence of new discourse referents. Vera Demberg (UdS) Dependency Locality Theory Dec 8th, 2014 2 / 12

DLT Integration Cost Dependency Locality Theory Key idea: predicts difficulty based on integration cost occurs when a head and its dependent are integrated discourse referents: number of DR between head and dependent Calculating Integration Costs for Relative Clauses SRC The reporter who *t* attacked the senator admitted the error. [Gibson 1998, 2000] Vera Demberg (UdS) Dependency Locality Theory Dec 8th, 2014 3 / 12

DLT Integration Cost Dependency Locality Theory Key idea: predicts difficulty based on integration cost occurs when a head and its dependent are integrated discourse referents: number of DR between head and dependent Calculating Integration Costs for Relative Clauses SRC DR: The reporter who *t* attacked the senator admitted the error. 0 1 0 1 0 1 1 0 1 [Gibson 1998, 2000] Vera Demberg (UdS) Dependency Locality Theory Dec 8th, 2014 3 / 12

Dependency Locality Theory DLT Integration Cost Key idea: predicts difficulty based on integration cost occurs when a head and its dependent are integrated discourse referents: number of DR between head and dependent Calculating Integration Costs for Relative Clauses SRC +2 DR: IC: The reporter who *t* attacked the senator admitted the error. 0 1 0 1 0 1 1 0 1 0 1 0 1 0 1 3 0 1 [Gibson 1998, 2000] Vera Demberg (UdS) Dependency Locality Theory Dec 8th, 2014 3 / 12

DLT Integration Cost Dependency Locality Theory Key idea: predicts difficulty based on integration cost occurs when a head and its dependent are integrated discourse referents: number of DR between head and dependent Calculating Integration Costs for Relative Clauses ORC The reporter who the senator attacked *t* admitted the error. [Gibson 1998, 2000] Vera Demberg (UdS) Dependency Locality Theory Dec 8th, 2014 3 / 12

DLT Integration Cost Dependency Locality Theory Key idea: predicts difficulty based on integration cost occurs when a head and its dependent are integrated discourse referents: number of DR between head and dependent Calculating Integration Costs for Relative Clauses ORC DR: The reporter who the senator attacked *t* admitted the error. 0 1 0 0 1 1 1 0 1 [Gibson 1998, 2000] Vera Demberg (UdS) Dependency Locality Theory Dec 8th, 2014 3 / 12

DLT Integration Cost Dependency Locality Theory Key idea: predicts difficulty based on integration cost occurs when a head and its dependent are integrated discourse referents: number of DR between head and dependent Calculating Integration Costs for Relative Clauses ORC +2 +2 DR: IC: The reporter who the senator attacked *t* admitted the error. 0 1 0 0 1 1 1 0 1 0 1 0 0 1 3 3 0 1 [Gibson 1998, 2000] Vera Demberg (UdS) Dependency Locality Theory Dec 8th, 2014 3 / 12

DLT Integration Cost Dependency Locality Theory Key idea: predicts difficulty based on integration cost occurs when a head and its dependent are integrated discourse referents: number of DR between head and dependent Calculating Integration Costs for Relative Clauses SRC +2 DR: IC: The reporter who *t* attacked the senator admitted the error. 0 1 0 1 0 1 1 0 1 0 1 0 1 0 1 3 0 1 ORC +2 +2 DR: IC: The reporter who the senator attacked *t* admitted the error. 0 1 0 0 1 1 1 0 1 0 1 0 0 1 3 3 0 1 Vera Demberg (UdS) Dependency Locality Theory Dec 8th, 2014 3 / 12

Try for yourselves Dependency Locality Theory Calculate integration costs for the following two sentences: The student thought that the professor asked a question. The student that the professor asked a question happily answered. Recipe: 1 mark discourse referents 2 draw dependencies 3 count discourse referents between head and left dependents 4 add discourse referents and intervening referents to calculate integration cost. Vera Demberg (UdS) Dependency Locality Theory Dec 8th, 2014 4 / 12

Dependency Locality Theory Further cases that can be explained by DLT CC/RC Complement clause, then relative clause The fact that the employee who the manager hired stole office supplies worried the executive. RC/CC Relative clause, then complement clause The executive who the fact that the employee stole office supplies worried hired the manager. The effect cannot be explained by previous theories of sentence processing. Let s compare the integration cost at the verbs. Vera Demberg (UdS) Dependency Locality Theory Dec 8th, 2014 5 / 12

Dependency Locality Theory Additional cases explained Adding a new discourse referent at a nested location increases complexity: a) The possibility that the administrator who the nurse supervised lost the medical reports didn t bother the intern from the maternity ward. b) The possibility that the administrator who the nurse from the maternity ward supervised lost the medical reports didn t bother the intern. Vera Demberg (UdS) Dependency Locality Theory Dec 8th, 2014 6 / 12

Dependency Locality Theory DLT Storage Cost Idea: storing open dependencies in memory is not only difficult at retrieval time but also while they have to be maintained in memory. Calculating Storage Costs for Relative Clauses ORC The reporter who the senator attacked *t* admitted the error. SC: 2 1 3 4 3 1 1 1 0 Vera Demberg (UdS) Dependency Locality Theory Dec 8th, 2014 7 / 12

Dependency Locality Theory DLT Storage Cost Calculating Integration and Storage Costs ORC The reporter who the senator attacked *t* admitted the error. IC: 0 1 0 0 1 3 3 0 1 SC: 2 1 3 4 3 1 1 1 0 Integration Costs measured in Energy Units (EU) Storage Costs measured in Memory Units (MU) Vera Demberg (UdS) Dependency Locality Theory Dec 8th, 2014 8 / 12

DLT Linking Theory Dependency Locality Theory How Integration Cost and Storage Cost interact and affect processing times. Assumption: energy units (EU) needed for integration and memory units (MU) needed for storage draw on the same pool of resources. At any point in time (TU), only a fixed amount of resources is available. the more open dependencies have to be maintained, not many resources are left for integration, so processing has to get slower. Dealing with Ambiguity: Prefer analyses with lower storage cost and/or lower integration cost. Analyse together in class: The bartender told me that the suspect left the country yesterday. Vera Demberg (UdS) Dependency Locality Theory Dec 8th, 2014 9 / 12

Dependency Locality Theory Discussion Predictions depend on dependency theory. Why count discourse referents? More complex memory access model which reflects activation, interference, decay [Warren and Gibson 2002] Vera Demberg (UdS) Dependency Locality Theory Dec 8th, 2014 10 / 12

Another Example Dependency Locality Theory reading times largest for relative clause with definite description slightly elevated reading times on aux and adv (storage costs?) Vera Demberg (UdS) Dependency Locality Theory Dec 8th, 2014 11 / 12

Dependency Locality Theory Summary of DLT Difficulty is caused by integrating upcoming words with previous structure. Integration of a word is the more difficult the more discourse referents have intervened since processing the word it integrates with. Maintaining open dependencies in memory also causes difficulty. Storage and integration draw on the same resources, such that integration is slower the more open dependencies have to be maintained. Explains the relative clause asymmetry, center embedding, RC/CC vs. CC/RC complexity difference, difference between sentences with new discourse referents vs. pronouns. for more detail read [Gibson 1998, 2000] Vera Demberg (UdS) Dependency Locality Theory Dec 8th, 2014 12 / 12