Inner Speech

Question 1

what is the broad definition of inner speech?

Answer 1

• silent speech experience in the mind
• shared by many but not all ~25%
• interacts with cognition and consciousness
• dysfunction in mental disorders

Question 2

what are the three theories of inner speech given?

Answer 2

• speech with attenuated articulation ([doesn’t explain the self-regulatory function of inner speech] Watson 1913)
• internalised speech by complex transformation (Vygotsky 1934/87)
• part of the phonological loop and phonological store in working memory (Baddeley & Hitch 1974)

Question 3

what is Vygotsky’s theory?

Answer 3

• child directed speech with caregiver creates a dialogue
• “balance, balance”, “look where you are going”, “well done joe”
• child can use this to start self regulating
• initially saying it outloud then internalising it

Question 4

what is the evidence for his theory?

Answer 4

• we tend to talk to ourselves as a dialogue rather than a monologue
• explains role of speech in self-regulation
• developmental theory - hard to track children from birth to 20s to prove it

Question 5

what are the methodological considerations?

Answer 5

• difficult to study
• questionnaires
• experience sampling
• phonological judgements - rhyming where you need to generate sounds - not naturalistic
• instructed imagery - give a cue and get them to imagine saying this in your voice (different from spontaneous inner speech)

Question 6

how does speech production work in inner speech

Answer 6

• corollary discharge - prediction of the sound of one’s voice generated by the motor system
• sending a copy of the speech signal to other parts of the brain
• normally used to filter self-caused sounds from perception
• need a system to make sure that we know that when we hear our own voice (it’s own voice) - motor system sends out a signal to the rest of the brain signalling that you are about to speak so the stimulus is probably been generated from you

Question 7

look at image on slide 17

Answer 7

• motor movements end in the auditory system
• motor - somatosensory - auditory cortex
• articulatory planning→ somatosensory estimation → auditory representation
• since inner speech in an internal copy of you external voice it makes sense that it may be using a similar mechanism
• activation of speech production regions in tasks to elicit inner speech
• phonological judgements
  - rhyme judgements
  - metrical stress judgements
• imagined speaking
  - imagining saying a sentence

Question 8

what is rhyme judgements

Answer 8

• speech production areas are engaged by the rhyme judgements
• e.g., jeans + greens - do they rhyme
  
  • requires phonological activation -> inner speech
• string matching
• e.g., zxstkl & zxstkl - do they match
  
  • doesn’t require phonological activation

Question 9

what areas are engaged in inner speech production

Answer 9

• left inferior frontal gyrus (Brocas area)
• left premotor cortex
• supplementary motor area

Question 10

how do you observe corollary discharge?

Answer 10

• own voice sounds different from a recording
• the sound you produce is attenuated by own inner speech when you hear it back
• you notice when you make a speech error
• the sound you produce is checked against an internal prediction to check it is produced correctly

Question 11

what are the limitations to the corollary discharge model of inner speech?

Answer 11

• can explain inner speech in own voice but not other peoples voices
• incompatible with the observation that inner speech is faster than overt speech
• explains deliberate inner speech but not spontaneous inner speech
• restricts investigations to internal monologue which is incompatible with the dialogic variety of inner speech reported

Question 12

is a perceptual mechanism needed to support spontaneous inner speech?

Answer 12

• Task-Elicited Inner Speech
  
  • Visual prompt (to say ‘elephant’)
  • Imagine saying the word
• Spontaneous Inner Speech
  
  • Instructed to just relax, wear a random beeper
  • When it beeps, write down mental activity immediately on a clipboard on the lap
  • 36 beeps in total
• This is called Descriptive Experience Sampling
• Not all types of inner speech rely on corollary discharge
• Spontaneous inner speech is driven by activity in the auditory perceptual system

Question 13

is the auditory cortex activated in silent speech?

Answer 13

• Higher activations of the right TVA when reading direct quotes
• More vivid auditory representations (i.e. “inner speech”)
• refer to slide 28 for more info

Question 14

what is the difference between deliberate & spontaneous speech in activation?

Answer 14

• Meta analysis: Activation Likelihood for Spontaneity (Deliberate vs. Spontaneous):
  
  • Deliberate:
    
    • Supplementary Motor Area (BA6)
    • Precentral Gyrus (BA6)
  • Spontaneous:
    
    • Middle Temporal Gyrus (BA22)

Question 15

what are neural oscillations?

Answer 15

• neurons firing rhythms capture speech rhythms
• Speech Amplitude Envelope
  
  • Energy bursts profile in speech
• Neural Oscillations
  
  • Rhythmic cycles of neuronal excitability
• Groups of neurons in the auditory cortex firing rhythmically at different frequencies
• Collectively generate ‘brain waves’

Question 16

what are the varieties of inner speech generation & organisation?

Answer 16

• The raw ingredients of inner speech may be generated differently
• Motor Command  Corollary Discharge
• Visual Letters  Phonological Lexicon
• Other means of verbal activation…
e.g., thinking (mind wandering)?
  
  • If sampled in a ‘speech-like’ rhythm in the auditory system
  • It sounds like internal speech