Thinking & Language

Overview – Thinking & Language

Thinking and language are central to human cognition and communication. These processes allow us to encode, interpret, and convey complex ideas, emotions, and intentions. From early childhood through adolescence, communication develops across verbal, non-verbal, expressive, and receptive domains, and disruptions can signal developmental, congenital, or acquired pathology.

Communication

What is Communication?

• The exchange of ideas between two or more people
• Involves transmission and response/feedback
• Includes verbal and non-verbal elements
• Communication does not require speech or language (e.g. infants use gestures, vocalisations)

Importance of Communication

• Express thoughts and feelings
• Establish identity
• Build and maintain relationships
• Enable teaching, learning, and business transactions

Aspects of Communication

• Language (Expressive & Receptive)
• Speech
• Voice
• Fluency

Language

What is Language?

Language is the coding of meaning into a symbolic system (e.g. words, sentences, texts) to convey ideas and emotions.

Four Components of Language

Form

1. Phonology – the sound system of language
   • Phoneme: distinct sound units (e.g. /f/, /m/, /k/)
2. Morphology – use of grammatical markers (e.g. suffixes, tense, plurality)
   • Free morphemes: standalone words (e.g. run, yellow)
   • Bound morphemes: modifiers (e.g. -ing, -ed, -s)
3. Syntax – structure and word order (e.g. noun → verb → object)

Content

4. Semantics – the meaning of words and phrases

Grammar = Morphology + Syntax

Speech

What is Speech?

Speech is the production of sounds that form spoken words.

Components of Speech

• Phonemes – individual sound units
• Syllables – phoneme clusters with a vowel sound
• Prosody – rhythm, pitch, stress, intonation, and duration

Fluency

• Refers to the flow of speech, including rhythm and timing

Voice

What is Voice?

Voice is the generation of sound through:

• Respiratory system (airflow)
• Larynx (vocal fold vibration)
• Vocal tract (resonance)

Key Characteristics

• Pitch
• Loudness
• Quality and tone

Modes of Communication

Verbal / Written Communication

• Pragmatics – the use of language in context
  • Conversational and cultural conventions
  • Politeness, bluntness, literal vs non-literal language
• Language, speech, voice, fluency

Non-Verbal Communication

• Body language
• Facial expressions
• Gestures
• Vocal intonation and rhythm

Process of Communication

Speech Production

• Linguistic encoding of meaning into words
• Motor translation:
  • Respiratory muscles (airflow)
  • Laryngeal muscles (phonation)
  • Articulators (tongue, lips, jaw, palate)

Hearing & Comprehension

• Sound wave transduction → electrical impulses → interpretation by brain

Language Domains

• Receptive language – comprehension of spoken or written language
• Expressive language – production of spoken or written language

Development of Communication Skills

Infants (6–12 months)

• Speech: babbling (syllables, no meaning)
• Language: understand ~3–50 words

Toddlers (1–2 years)

• Speech: first words, up to 200-word vocabulary
• Language: understand 50–300 words, ask/answer simple questions

Toddlers (2–3 years)

• Speech: ~1000 words, master “early 8” sounds (e.g. m, b, p, d)
• Language: follow directions, understand stories, answer “wh-” questions

Early Childhood (3–5 years)

• Speech: >2000 words, master “middle 8” sounds (e.g. k, g, t, f, ch)
• Language: understand up to 10,000 words, use complex grammar and pragmatics

Primary School (5–12 years)

• Speech: abstract vocabulary, “late 8” sounds (e.g. s, z, l, r), consonant clusters
• Language: understand stories, explanations, jokes, instructions

High School (13–18 years)

• Speech: vocabulary exceeds 10,000
• Language: advanced forms – debate, satire, argument, academic writing

Causes of Communication Defects

Acquired

• Hearing loss
• Traumatic brain injury
• Meningitis

Congenital

• Cleft palate/lip
• Craniofacial anomalies
• Syndromes (e.g. Down syndrome)
• Intellectual disability

Developmental

• Social deprivation
• Parental neglect

Types of Communication Deficits

Receptive Language Delay

• Poor comprehension of words or stories
• Inability to follow instructions
• Reliance on context clues

Expressive Language Impairments

• Limited vocabulary, word-finding issues
• Omitted grammar (e.g. “He swimming beach”)
• Poor sentence construction
• Difficulty with storytelling or essays

Pragmatic Impairments

• Inappropriate content for context
• Conversation breakdowns (e.g. interruptions, ignoring questions)
• Misuse of non-verbal cues (e.g. poor eye contact)

Speech Impairments

• Substitution or omission of sounds (e.g. “puter” for “computer”)
• Slurred or imprecise speech
• Disrupted rhythm

Voice Impairments

• Hoarseness, breathiness
• Absent or inappropriate pitch
• Pitch breaks

Fluency Impairments

• Hesitations, abnormal rhythm
• Stuttering:
  • Repetitions
  • Prolongations
  • Blocks

Red Flags in Development

Speech

• Missing sounds at >2 years
• Speech unintelligible at >3 years
• Persistent errors after 5 years

Language

• No response to sounds >4 months
• Not speaking by 2 years
• No simple sentences by 2.5 years
• Poor grammar or comprehension <4 years
• Behaviour problems or poor social skills
• Learning and communication difficulties at school

Summary – Thinking & Language

Thinking and language are foundational to communication, learning, and social connection. From the early stages of babbling to the mastery of abstract and academic language, these processes are shaped by biological, developmental, and environmental factors. Recognising deficits early can guide timely intervention. For a broader context, see our Psychiatry & Mental Health Overview page.