the speaking brain

Question 1

What is word retrieval?
What are the three stages involved in word retrieval during speech production?

Answer 1

Word retrieval - translating an idea into a sentence structure and producing the appropriate word.
Lexicalisation: Selecting a word based on the intended meaning.
Selecting the lemma: Retrieving and specifying the grammatical properties of the word.
Selecting the lexeme: Retrieving the phonological patterns needed to articulate the word.

Question 2

define the following words: the lemma the lexeme

Answer 2

the lemma - modality independent, word-level info that specifies syntatic components
the lexeme - phonological code that drives articulation

Question 3

Outline the stages of speech production and the deficits associated with each stage.

Answer 3

Semantics (wernicke’s aphasia) - word retrieval - syntax (broca’s aphasia) - working memory (logopenic aphasia) - articulation (dysartheia, apraxia of speech)

Question 4

Explain the following speech errors and how they arise:
Freudian slip
Tip-of-the-tongue
Spoonerism
Malapropisms

Answer 4

Freudian slips - one word is substituted for another, possibly revealing hidden intentions. Due to an issue with lexicalisation/lemma selection.
(ToT) phenomenon,- speaker knows the concept but struggles to retrieve the corresponding word. Due to issues with lexeme/phoneme-level errors.
Spoonerisms - initial consonants are swapped between words. Due to issues with lexeme/phoneme-level errors.
Malapropisms - saying a word with a similar phonological form to the intended word. Due to issues with lexeme/phoneme level erros.

Question 5

What are the key differences between Levelt’s and Dell’s models of word retrieval?

Answer 5

Levelt’s model suggests word retrieval occurs in two sequential stages: lemma selection followed by lexeme retrieval. Dell’s model, a modernized version, adds interactivity and simultaneous activation of multiple kinds of information (semantic, lexical, phonological), explaining mixed errors through a competitive process where the “winning” word is selected.

Question 6

What is Broca’s aphasia, and how does it relate to syntax processing?

Answer 6

Broca’s aphasia is characterized by impairments in producing sentences (agrammatism) due to damage to Broca’s area. Syntax processing occurs in Broca’s area, as evidenced by agrammatism in patients with Broca’s aphasia. Syntax processing may also involve interaction with semantic properties, as indicated by the activation of anterior and posterior temporal lobe structures during syntactic processing.

Question 7

How does working memory influence syntax processing, and what evidence supports this relationship?

Answer 7

Working memory capacity may affect the processing of syntactically demanding sentences, as shown in studies of logopenic aphasia. Patients with impaired phonological working memory exhibit deficits in sentence comprehension and repetition, particularly with longer sentences. Neuroimaging studies have identified brain regions associated with syntax (BA44) and working memory demands (BA45), suggesting an interaction between the two processes.

Question 8

What is speech apraxia, and how does it differ from dysarthria?

Answer 8

Speech apraxia involves difficulty in shaping the vocal tract to form words despite intact semantics, syntax, and word retrieval. It is associated with damage to the insula. Dysarthria, on the other hand, is characterized by impairment in muscular contractions of articulators, also leading to altered speech production despite intact language components. Dysarthria is associated with damage to the cerebellum and basal ganglia.

Question 9

What are the limitations of Levelt’s model?

Answer 9

Mixed errors - (speech errors where the intended word and produced word are similar semantically and phonologically)
mixed errors suggest there is an interaction between different elements of speech production
ToT - what about when you just know it starts with a certain phoneme?
Shouldn’t be able to retrieve the sounds of the word if you haven’t retrieved what the word is yet

Question 10

Outline Levelt’s model of word retrieval. What evidence is there to support this model?

Answer 10

Levelt’s model proposesthat word retrieval happens in 2 discrete, sequential stages. Beginning with the lemma selection and then lexeme retrieval.
Evidence from natural speech - rarely make errors where we use a homophone in the wrong grammatical way. Suggests we collect the right lemma (grammar) before the lexeme.
Evidence from speech errors ToT- completed lemma stage but got stuck on lexicalisation stage.

Question 11

Outline Dell’s model of word selection.

Answer 11

Model proposes interactivity between Levelt’s stages (lexicalization, lemma, and lexeme components.)
Word selection involves simultaneous activation of semantic, lexical, and phonological information through a competitive process. The competitive process involves nodes activation triggered by input, with activation levels determined by connection weightings. The winning word pattern is retrieved when activation surpasses a threshold. This process can be altered by adjusting connection weightings.

Question 12

How does Dell’s model explain mixed erros and ToT phenomenon?

Answer 12

Mixed errors - caused by interactivity and simultaneous activation of semantic and phonological layers i.e produced word is both phonologically and semantically similar (“oyster” for “lobster”)
ToT - also explained by interactivity. Activation of phonological layer but a word hasn’t ‘won’ the competition yet = T-o-T phenomenon whilst knowing it starts with a certain phoneme

Question 13

Outline the evidence which supports Dell’s model.

Answer 13

Logopenic progressive aphasia (LPA) = Speech characterised by word-finding impairment and phonological speech errors (phonemic paraphasias – sound substitution, e.g., “tephelone” instead of “telephone”), but semantic memory is intact
Dell’s model could simulate this pattern of impairment with issues with the phonological-lexical layer, with intact semanticlexical layer

Question 14

Outline the SLAM model of speech production.

Answer 14

The SLAM model suggests a sequence from semantic processing to motor execution in speech production. It is supported by evidence from lesion-symptom mapping and neuroimaging studies, showing distinct brain regions involved in semantic processing, lexical access, auditory processing, and motor control.

Question 15

Outline the SLAM model of speech production.

Answer 15

Dual stream of speech production:
A dorsal stream for speech production (motor):
o Auditory information is passed through the parietal lobe to the inferior frontal gyrus and motor cortex
o Dorsal stream alone = leads to word repetition
Ventral stream for speech comprehension (semantics):
o Auditory information is passed through temporal cortex to temporal pole for comprehension (semantic knowledge)
Two together:
proposed that speech production involves both streams; ventral stream in reverse then the dorsal stream:
Semantic → Lexical → Auditory → Motor
(aka) Temporal lobes → Auditory cortex → inferior parietal cortex → frontal cortex

Question 16

What evidence is there to support the SLAM model?

Answer 16

neuroimaging evidence found activation of both the streams
evidence from lesion-symptom mapping - mapped language impairment to the white matter connections between regions of two streams

Question 17

Define syntax and parsing. Where do these processes occur?

Answer 17

Syntax: the rules that specify how words can be combined into sentences
Parsing: assigning a syntactic structure to words
Assumed to occur in Broca’s area

Question 18

What is Broca’s aphasia? How can it be tested?

Answer 18

Broca’s aphasia = Impairments in production of sentences, agrammatism resulting in speech which is characterised by the absence of function words and verbs
 Agrammatism assessed through the ‘Cookie Theft’ test:
* Shown an individual an image of a cookie being stolen – how image is described tells you whether someone has Broca’s aphasia or not e.g will describe the image like ‘cookie’ ‘boy’ and lack functional/connecting words

Question 19

What evidence is there to support the idea that syntax and parsing/semantics processing are separate (Broca’s area, ERP, neural evidence)?

Answer 19

fMRI study of 13 ppt who were asked to judge the validity of sentence with increasing grammatical complexity.
Broca’s area (BA44) showed greater activity with comprehension (not production) of sentences with increasing syntactic complexity

ERP Studies - N400 (semantic anomalies regardless of sentence context), P600 (syntactic anomalies regardless of semantic context)

Anterior and posterior temporal lobe structures also active for syntactic vs. semantic processing
o Semantically demanding – BA45, GTm – middle temporal gyrus
o Syntactically demanding – BA44, STS – superior temporal sulcus

Question 20

Are syntax and parsing processing separable? This depends on whether parsing is viewed as…

Answer 20

Structure-driven: based only on syntactic properties
= syntax separate from semantics
Discourse-driven: influenced by semantic properties of words
= semantics integrated with syntactic processing

Question 21

What is Logopenic aphasia?

Answer 21

Word-finding impairment due to impaired phonological working memory
Sentence comprehension deficits affected by sentence length not syntactic complexity
Impaired sentence repetition due to sentence length

Question 22

What evidence is there to support the idea that syntax and parsing processing are connected (Broca’s area, ERP, neural evidence)?

Answer 22

Evidence that syntax and semantics and working memory connections
Broca’s area is actually 2 Broadmann’s areas: BA44 (posterior) processing hierarchical structures and sequences (e.g sentence-level constructions), BA45 (anterior) working memory and semantic control (judging semantic-ness such concreteness or synonym judgments)

Question 23

Define articulation and syllabification.

Answer 23

• Articulation = formation of clear and distinct sounds in speech
• Syllabification = process of segmenting phonological information into syllables across adjacent morphemes and adjacent words

Question 24

Outline the differences between speech apraxia and speech dysarthia

Answer 24

Speech Apraxia
o Difficulty in shaping the vocal tract to form words
o Alters speech production despite intact:
 Semantics, syntax
 Word retrieval
 Muscle tone of articulators
o Associated with damage to the insula

Dysarthria:
* Impairment in muscular contractions of articulators
* Altered speech production despite intact:
o Semantics, syntax
o Word retrieval
* Associated with damage to the cerebellum and basal ganglia

Question 25

What evidence is there to suggest we have specialised areas for speech articulation?

Answer 25

research suggests we have for phoneme (syntax) and a specific region for syllables (syllabification)

Also found that we have separate areas for areas which plan to articulate, and areas which do - stimulating left inferior parietal areas led participants to believe they had moved their lips to talk, stimulating the premotor region triggered mouth movements that ppt were not consciously aware of

Question 26

What is a garden path sentence, and how does it relate to parsing?

Answer 26

A garden path sentence is one that leads the reader or listener down the wrong syntactic path initially. Adding semantic information can influence parsing of these sentences.