Bayley’s Behaviour for TAs, Taking Risks with the Teacher

I was priveleged or honoured, to have Behaviour expert John Bayley offer myself and another teaching assistant advice on managing the behaviour with a challenging KS3 class which we shared.

Behaviour expert John Bayley offered teaching assistants advice on managing the behaviour of a challenging KS3 class working with a fantastic teacher!

Please view my five minutes of fame here:

Bayley’s Behaviour for TAs, Episode 2: Taking Risks with the Teacher, 2008,


Children’s Speech and Language development and disorders glossary

Affricate – the hard sound in speech.

Affricates – generally referred to as ‘the affricates’ – are individual consonants made with ‘affrication’.
English has two affricates. The voiceless affricate is ‘ch’, heard twice in the word ‘church’, and the voiced affricate is the sound that is heard twice in the word ‘judge’.
The place-voice-manner (PVM) chart below shows the voiceless palatal affricate as in ‘etch’ and the voiced palatal affricate as in ‘edge’.

Age appropriateWithin Normal Limits (WNL)

Air flow; Air streamAll speech sounds are produced by making air move in the vocal tract. This movement of air is referred to as the ‘air stream’ or ‘air flow’.

Alveolar – Alveolar consonants, or ‘the alveolars’, are made with the narrowest point of constriction of the air stream at the alveolar ridge. This point of constriction is called the place of articulation. The alveolars in English, as shown on either a Consonant Chart or a place-voice-manner chart are: /t/, /d/, /s/, /z/, /n/, and /l/.

The Place-Voice-Manner (PVM) chart shows the voiceless and voiced alveolar stops /t/ and /d/, the voiceless and voiced alveolar fricatives /s/ and /z/, the voiced alveolar nasal /n/ and the voiced alveolar liquid /l/.

Alveolar ridge – the hard, bony, bumpy ridge between the top of the upper teeth and the hard palate.

Approximant – is a consonant made with little obstruction to the air stream.
The approximants in English are /l/ as in lay, /r/ as in ray, /w/ as in way and /j/ as in yay. In older terminology /w/ and /j/ were called semivowels. The phonetic symbol for the first sound in the words ‘yay’ and ‘you’ is /j/.

Articulation – We produce, or articulate, the sounds of speech by moving body parts (by contracting and relaxing muscles), and by making air move. Most of the movements for speech take place in the mouth and throat, and the chest where breath is controlled. The mouth and throat parts are called ‘the articulators’.
The principal articulators are the:
• lips,
• the lower jaw,
• the teeth,
• the soft palate (velum),
• the uvula,
• the larynx (voice box).

There are active articulators that can be moved into contact with other articulators (e.g., the tongue) and passive articulators which are ‘fixed’ (e.g., teeth, alveolar ridge, and hard palate).

Articulation TestCore Speech Assessment Battery

Audiogram a graph of hearing thresholds measured in decibels hearing level (dB HL) as a function of speech frequency measured in Hertz (Hz). All children with hearing and/or speech and/or language issues require an audiogram. A pure tone audiogram shows mild bilateral, high frequency hearing loss to indicate hearing thresholds.
Hearing thresholds are considered normal if they are in the range -10 to +15 dB HL. The dB HL-scale represents hearing levels relative to the hearing of young ‘otologically normal’ 18-30 year olds. Symbols on a graph will be used to represent the average speech level in each frequency region for conversational speech (59 dB SP at 1 m) spoken by an adult female. Even with this mild hearing loss, the highest frequency speech sounds (fricatives such as /s/) are close to the threshold of hearing, and speech energy above 4000 Hz is not audible. At greater distances more of the speech signal will be inaudible.
Hearing thresholds of 16-25 dB HL are classified a slight hearing loss, 26-40 dB as mild, 41-55 dB as moderate, 56-70 dB as moderate-severe, 71-90 dB as severe, and >90 dB as profound.

Babbling – In typically developing infants a gradual emergence of increasingly complex and speech-like utterances during the first two years of life. This period of non referential vocalisation is generally recognised as a foundation for meaningful speech and phonological development, which is babbling.
Babbling proceeds in three stages:
Basic Canonical Syllables,
Advanced Forms.

Backing – occurs when /k/, /g/ and ‘ng’ replace /t/, /d/ and /n/ respectively.
‘Tell Teddy to shut Tim’s door” sounds like ‘Kell Keggy koo shuck Kim’s gore’,
and ‘Put the red pen in the bin’ sounds like ‘Pook the reg peng in the bing’.
Backing can affect any of the obstruents shown on place-voice-manner charts (e.g., chew = coo or goo, ship = kip or gip). It is not seen in typical development in English, and is not a ‘natural’ or developmental process. Any child who is backing should be referred to a speech-language pathologist for assessment.

BlendConsonant Cluster

CPDContinuing Professional Development

Childhood Apraxia of Speech (CAS)a relatively rare Speech Sound Disorder (SSD) in which a child has difficulty planning and sequencing the movements required for speech, and difficulty with prosody. Most children with CAS have language difficulties in addition to their SSD. Most have a receptive-expressive gap, understanding language much better than they can use it to express themselves. CAS is regarded as a severe SSD and its incidence is less than 1% of a typical speech pathology caseload. Despite the similar sounding name, CAS is a different disorder from Apraxia of Speech (AOS) in adults, with different characteristics.

Childhood Apraxia of Speech (CAS) or Developmental Verbal Dyspraxia (DVD)
The ASHA definition of CAS includes Apraxia of speech in children irrespective of aetiology (that is, whether idiopathic or acquired).
RCSLT and DVD – the Royal College of Speech and Language Therapists (RCSLT) in the United Kingdom is Developmental Verbal Dyspraxia (DVD), using the word ‘dyspraxia’. The RCSLT definition, includes apraxia of speech in children in its idiopathic presentation, excluding from the definition children with acquired apraxia of speech -Developmental Verbal Dyspraxia (DVD).

Cleft; Cleft lip; Cleft lip and palate; Cleft palate – A cleft is a birth defect caused by failure of the mouth parts to fuse during early foetal development. Some babies are born with cleft lip only, and this may be unilateral (affecting one side of the lip) or bilateral (affecting both sides). Some children are born with unilateral or bilateral cleft palate. Some are born with any combination of cleft lip/palate types.

Cluster Reduction; Cluster Simplification -, is a phonological process (phonological pattern) in which a consonant cluster is omitted (e.g., ‘oo’ for ‘blue’), reduced (e.g., ‘boo’ for ‘blue’) or replaced with another sound (e.g., ‘woo’ for ‘blue’) or replaced with another cluster (e.g., ‘dwoo’ for ‘blue’).

Consonant a speech sound in which the airstream is obstructed (at the place of articulation).

Consonant chart – The most familiar consonant chart or phonetic chart is the one provided by the IPA. It is a grid with manner of articulation on the vertical axis and place of articulation on the horizontal axis. Each cell of the grid has one or two symbols. Where there are two symbols in a cell the one on the left is a voiceless consonant and the one on the right is a voiced consonant. A consonant chart is different from a Place-Voice-Manner Chart (PVM Chart).

Consonant Cluster – or ‘cluster’, is a sequence of two or more consonants. For example, /fl/ in ‘flower’ and /skw/ in ‘square’. Some speech pathologists call consonant clusters ‘blends’ which is a term more correctly applied to letter sequences in written language.

Consonant Harmony – a phonological process or phonological pattern in which one sound influences the way another sound in a word is pronounced. For example if a child says ‘tittytat’ for ‘kittycat’ the /t/ in ‘kitty’ and /t/ in ‘cat’ had impacted the production of the two instances of /k/, so that all the voiceless stops in ‘kittycat’ (both k’s and both t’s) are produced as /t/.

Core Speech Assesment Batterybegins with an audiogram administered by an audiologist, an oral musculature examination performed by the speech-language pathologist/speech and language therapist (SLP/SLT), and a detailed history taken by the SLP/SLT. Then independent and relational analyses, with the SLP/SLT exercising clinical judgement with regard to how detailed these need to be.

Independent Analysis (Inventories and Constraints) – provides a view of the child’s unique system without reference to the target (adult) phonology. It comprises the inventories of ‘what’s there’ in the child’s system, and a listing of the constraints, or what’s missing from the child’s system.

Relational Analysis (Percentages) – provides a normative comparison between the child’s speech sound system and an idealised version of the target (adult) system. It comprises the Percentage of Consonants Correct (PCC) in single words and conversational speech (if possible), the Percentage of Vowels Correct (PVC) in single words and conversational speech (if possible), a phonological analysis, a phonotactic analysis, and a syllable stress pattern inventory.
Not all errors will necessarily be of one type – Some children experience more than one type of problem concurrently. In the same child, some errors may have: a phonetic basis; a phonological basis; a perceptual basis; an anatomic/structural basis; a motor planning basis; or, a motor execution basis.

Further Evaluationoutcome of the Core Speech Assessment Battery may prompt more assessment to rule in/out, for example, perceptual difficulties, motor speech disorder (a dysarthria and /or CAS), or to take an in-depth exploration of the child’s stimulability.

DentalA dental consonant is one in which there is approximation or contact between the teeth and another articulator. The dental consonants in English may be labiodental like /f/ as in ‘phone’ and /v/ as in ‘veil’ with contact between the top teeth and lower lip, or interdental like the ‘th-sounds’, /θ/ as in ‘think’ and /ð/ as in ‘them’.

The place-voice-manner (PVM) chart shows four dental consonants:
the voiceless
 voiced labiodental fricatives /f/ and /v/
 the voiceless
 voiced interdental fricatives (the ‘th’ sounds).

Developmental Patterns / Developmental Processes – are speech simplifications produced by children that are found in typical development. Which include:
Final consonant deletion,
 Reduplication Weak syllable deletion,
 Cluster reduction,
 Context sensitive voicing,
 Depalatalization,
 Fronting (fricatives, velars),
 Alveolarization (stops. fricatives),
 Labialization (stops),
 Stopping (fricatives, affricates),
 Gliding (fricatives, liquids),
 Deaffrication,
 Epenthesis ,
 Metathesis,
 Migration.
 Developmental Verbal Dyspraxia (DVD)

The Royal College of Speech and Language Therapists (RCSLT) in 2011, in the UK officially adopted the term Developmental Verbal Dyspraxia (DVD) in preference to Childhood Apraxia of Speech (CAS) – the preferred term of the American Speech-Language Hearing Association (see Childhood Apraxia of Speech).
DVD refers to children whose motor speech disorder is ‘idiopathic’, having no known cause, and a distinction is made between these children and children who have apraxia of speech due to a ‘known’ (organic) cause. This is in contrast to the way the term CAS is used to refer to Apraxia of Speech in children in all its manifestations, irrespective of whether the cause is ‘known’ or ‘unknown’.

Diphthongis like a two-part vowel containing a glide from one vowel quality to another, as in ‘fear’ (‘fee-uh’) and ‘tour’ (‘too-uh’).

Dysfluency – see Stuttering

Evidence Based Practice (EBP) is the conscientious, explicit, and judicious integration of the best available; external evidence from systematic research; evidence internal to clinical practice, and evidence concerning the preferences of a fully informed patient.
Early 8, Middle 8 and Late 8

Final Consonant Deletionis a phonological process (phonological pattern) in which children omit the final consonants of words; for example ‘time’ pronounced as ‘tie’ or ‘make’ pronounced as ‘may’.

Fluency disorder or Stuttering
Functional or Idiopathic

Fricativea consonant made by forcing air though a narrow gap, generating a voiced or voiceless hissing sound. The fricatives in English are found at the beginnings of the following words: ‘sue’, ‘zoo’, ‘shoe’, ‘fee’, ‘vee’, ‘thigh’, ‘thy’ and ‘high’, and as the second consonant ‘zh’ in the word ‘measure’.
The place-voice-manner (PVM) chart shows the voiceless and voiced labiodental fricatives (/f/ and /v/), interdental fricatives (the ‘th’ sounds), alveolar fricatives ( /s/ and /z/) palatal fricatives ‘sh’, ‘zh’, ‘ch’ and dg’, and the voiceless glottal fricative (/h/)

Glide or semivowela name sometimes used for an approximant articulation which resembles a vowel in quality. Glides are also sometimes called semivowels. The glides on the PVM Chart are /w/ as in ‘woo’ and /j/ as in ‘you’.

Glue ear see Otitis Media with Effusion (OME)

Homophony (homonymy) – is the term used to describe a child’s production of different words the same way (e.g., ‘coat’, ‘coach’ and ‘Coke’ all pronounced as ‘tote’).

Hypernasal; Hypernasality
Hypernasal speech, or hypernasal resonance,
sounds as though the speaker is ‘talking through his/her nose’. It is referred to as ‘hypernasality’.
Hyponasal; Hyponasality Hyponasal speech, or hyponasal resonance, is characterised by a ‘blocked nose’ voice quality as though the speaker has a cold. ‘My mummy and Nanna made it for me’ sounds like ‘By bubby ad Dadda bade it for be’. It is referred to as ‘hyponasality’.

Identification – Screening

Idiopathicadjective used mainly in medicine meaning arising spontaneously or from an obscure or unknown cause. It is often used interchangeably with the term ‘functional’ which is sometimes used in medicine to describe symptoms which have no current visible organic basis.

Independent Analysis Core Speech Assessment Battery

Intelligibility – refers to the proportion of a speaker’s output that a listener can readily understand. In typical speech development, children’s comprehensibility steadily increases; by their fourth birthday typically developing children are 100% intelligible to strangers.

Initial Consonant Deletion – is a phonological process (phonological pattern) that occurs when a child omits the first sound of many (but not necessarily all) words or syllables.
For example, ‘Get me that nice orange Lego piece’ might sound like ‘Et me at ice or-ee eh-oh eese’.
ICD is only found in typical development of Hebrew, Finnish and French.
Any child learning English who deletes initial consonants should be referred to a SLP/SLT.

International Phonetic Alphabet – IPA Consonant Chart
The International Phonetic Alphabet is a system used to write down the sounds, syllables, intonation and separation of words in spoken language. It is based on the Latin alphabet with additional symbols. The (pulmonic) consonant chart is followed by the most recent version of the Full Chart.

ICPLA Extensions to the IPA – transcribing atypical speech e.g., the speech of a person with a speech sound disorder related to cleft palate; symbols called the Extensions to the IPA are used.

International Phonetic Association (IPA) – is responsible for the development

Languagethe symbolisation of thought. It is a learned code, or rule system that enables us to communicate ideas and express wants and needs. Reading, writing, gesturing and speaking are all forms of language. Language falls into two main divisions: receptive language: understanding what is said, written or signed; and, expressive language: speaking, writing or signing.

Language Assessment – a comprehensive evaluation performed by a speech-language pathologist / speech anf language therapist. It covers receptive language function (‘comprehension’), expressive language function (‘expression’) and the pragmatics of language use. It may involve standardised language tests such as the CELF or the CASL yielding Standard Scores and Percentile Ranks, and/or skilled informal and formal observations.

Language Disorder – A child with a Language Disorder (Language Impairment) exhibits receptive and/or expressive and/or pragmatic language abilities that are inappropriate (or not within normal limits) for their age, intelligence, etc.

Larynx – the larynx (‘voice box,’) is situated in the neck at the top of the trachea (‘wind pipe’). The larynx contains the vocal cords (vocal folds).


Liquid is a term used to refer to /r/ and /l/. The lateral liquid is /l/ and the rhotic liquid is /r/, as shown on the PVM Chart below.

‘Lisp’ is a widely used lay term for difficulties pronouncing certain sounds, particularly /s/ and /z/. Speech pathologists may use this term, but they are more likely to describe the nature of the error, for example ‘Interdental s’, ‘Lateral affricates’, etc.
Long word
A ‘long word’ has more than two syllables. Examples include: ambulance, hippopotamus, computer, spaghetti, vegetables, helicopter, animals, caravan, caterpillar, and butterfly. See the Glossary entry for Multisyllabic words.
Manner of Articulation
Consonants are classified in terms of their Place-Manner-Voice. The manner of articulation is the type of obstruction that occurs in the production of a particular consonant. The ‘manners’ of articulation are: Stop, Fricative, Affricate, Nasal, Liquid and Glide. The Stops, Fricatives and Affricates are termed obstruents, and the Nasals, Liquids, Glides, AND VOWELS are termed sonorants. The consonants /l/, /r/, /w/ and /j/ are also referred to as approximants.
Maximal Opposition
A maximal opposition cuts across many featural dimensions. For example the word pair bun-sun differs in place (labial is distinct from coronal), manner (stop is distinct from fricative) and voice (/b/ is voiced and /s/ is voiceless). The contrast fat-gnat is in place, manner, voice and major class (/f/ is an obstruent and /n/ is sonorant), and markedness (/f/ is marked, /n/ is not).

Minimal Opposition
A minimal contrast or minimal opposition is defined by one feature difference.
For example, sip-zip involves a minimal difference in voice; sip-ship involves a difference in place; and, sip-tip involves a difference in manner. A contrast like shape-jape is not quite ‘minimal’, differing in manner and voice. Test your knowledge.
Minimal Pair
A minimal pair comprises two semantically different words that also differ by one phoneme, e.g., me-knee, cry-try, bus-buzz, mat-mitt. See the Glossary entry for Near Minimal Pair below.

Modelling and recasting

Modelling and recasting are conversational techniques used by SLPs/SLTs, parents and teachers to help children’s speech and language development.

Multiple Opposition
Multiple oppositions are constructed when one sound is contrasted with many, as in ‘dip’ vs. ‘lip’, ‘ship’, ‘grip’ and ‘chip’ (dip-lip, dip-ship, dip-grip, dip-ship) in a treatment set in the variation of Minimal Pairs therapy called Multiple Oppositions Therapy (Multiple Oppositions Intervention).

See the Glossary entry for Associations

Multisyllabic words
Some experts define multisyllabic words as words of more than one syllable, and others define them as words of more than two syllables. There is a tendency among researchers nowadays to avoid the terms ‘multisyllabic words’ and ‘polysyllabic words’ and to use the terms ‘one syllable words’, ‘two syllable words’ and ‘long words’ instead. See the Glossary entry for Long words.

Mutual Recognition Agreement
See the Glossary entry for Associations

Nasal; ‘The Nasals’
means relating to the nose, e.g., ‘nasal consonant’, ‘nasal resonance’, ‘hypernasal’, ‘hyponasal’. Nasal consonants, commonly called ‘the nasals’, are made with air escaping only through the nose. To produce nasals the soft palate must be lowered to let air escape past it and down the nose. At the same time the soft palate must close off the opening to the oral cavity to prevent air from escaping through it. Children with cleft palate cannot do either, so their palates must be surgically repaired. There are three nasal consonants in English /m/ as in ‘rum’, /n/ as in ‘run’ and ‘ng’ as in ‘rung’.

The place-voice-manner (PVM) chart above shows the three nasals, all of which are voiced. The /m/ is bilabial, /n/ is alveolar, and ‘ng’ is velar.

Near Minimal Pair<br />
Near minimal pairs occur in syllable structure contrasts, e.g., back-black, an-ant, up-cup, tinkle-twinkle, bee-bees, and relate to the inclusion or exclusion of a consonant. See the Glossary entry for Minimal Pair above

Non-developmental Patterns
or non-developmental processes are speech simplifications produced by children that are not found in typical development. They include Initial consonant deletion (ICD is found in the typical development of Finnish, French and possibly Hebrew), Intrusive consonants, Backing (stops, fricatives, affricates), Denasalization, Devoicing of stops, Sound preference substitutions (Systematic sound preference), Deletion of unmarked cluster element, Glottal replacement and Final vowel addition. See the Glossary entry for Developmental Patterns above.

Obstruents, shown on the PVM Chart above, are consonants made by obstructing the airstream.

Otitis media with effusion (OME)
Otitis media with effusion (OME) is commonly called ‘otitis media’, ‘glue ear’, ‘middle ear disease’ or ‘middle ear infection’.

Palatal fronting<br />
Palatal Fronting is a phonological process in which the palatal fricatives are produced as /s/ or /z/, so that ‘ship’ and ‘shine’ sound like ‘sip’ and ‘sine’ and ‘measure’ and ‘explosion’ sound like ‘mezza’ and ‘exploe-zun’.


The palate is the ‘roof of the mouth’. It comprises the hard palate which runs from the alveolar ridge at the front of the mouth to the beginning of the soft palate (velum) at the back; and the soft palate, which extends from the rear of the hard palate nearly to the back of the throat, terminating in the uvula.

Phoneme; Phonemic level
For many scholars the phoneme is the fundamental unit of phonology. Phonology, as an area of study, has shown that spoken language can be broken down into a string of sound units (phonemes), and that each language has a small, relatively fixed set of these phonemes. Most phonemes can be put into groups (stops, fricatives, etc.).

Phoneme Collapse
A phoneme collapse is a phonological rule. Phoneme collapses are seen as compensatory strategies that are organised according to aspects of adult system in terms of place and manner of articulation and voicing. Analysis in terms of phoneme collapses provides a holistic assessment of child’s speech that is child-based rather than adult-based (Williams, 2000a). The following example is of a phoneme collaps of one sound to many occasioning extensive homophony (different words pronounced the same way).

Phonetic development; Articulation development<br />
Phonetic development is the development of the ability to articulate individual speech sounds or ‘phones’. The phonetic level takes care of the motor (articulatory) act of producing the vowels and consonants so that we have a repertoire all the sounds we need in order to speak our language(s).

Phonetic transcription
Phonetic transcription is the process of writing down a person’s speech using phonetic symbols. Speech-language pathologists in Australia and most of the world use the International Phonetic Alphabet (IPA) to do this. There are symbols for vowels, diphthongs, triphthongs, consonants, pauses and intonation to use in broad transcription, as well as numerous symbols called ‘diacritics’ to use in narrow (very detailed) transcription.

Phonetics, a branch of Linguistics, is the scientific study of speech. Sometimes a phonetic transcription is said to be written (or transcribed) ‘in phonetics’.

Phonemic development; Phonological development
Phonemic or phonological development is the gradual acquisition, by children, of an adult-like speech sound system. The phonological or phonemic level is in charge of the brainwork that goes into organising the speech sounds into patterns of sound contrasts so that we can make sense when we talk.
A child of five years old, with a phonemic (phonological) difficulty might find it impossible to make the sentences ‘He cut himself on the glass’ and ‘He cut himself on the grass’ sound different from each other (i.e., contrast with each other), perhaps pronouncing them both as, ‘He tut himseff on da bwaht’.

Phonological analysis
Phonological analysis is one component of Independent Analysis (see the Glossary entry for Core Speech Assessment Battery. In a basic phonological analysis the SLP/SLP phonetically transcribes single words and conversational speech and then evaluates what the child has in his or her phonological system, what is missing, and what intervention is needed.
In a detailed speech assessment for children with moderated through to severe SSD the SLP/SLT conducts both an Independent Analysis (looking at the child’s own system in detail) and a Relational Analysis (comparing it to the adult target system).

Phonological disorder
A phonological disorder is a speech sound disorder that affects the phonological (phonemic) level. The child has difficulty organising speech sounds into a system contrasts. These contrasts are called ‘phonemic contrasts’.

For a listener, the most obvious characteristics of phonological disorder are the child’s poor intelligibility, and the presence of homophony (homonymy).

Homophony is the term used to describe a child’s production of different words the same way (e.g., ‘coat’, ‘coach’ and ‘Coke’ all pronounced as ‘tote’).

Phonological disorder is sometimes referred to as a Speech Sound Disorder that occurs at the linguistic, cognitive or language level.

Phonological processes; Phonological patterns
Phonological processes or phonological patterns are descriptions of the predictable, simplified productions (like ‘wabbit’ for rabbit, ‘boon’ for spoon, ‘lellow’ for yellow and ‘mato’ for tomato) typically found in young children’s speech when they are learning to talk.
The phonological processes include Final Consonant Deletion, Velar Fronting, Stopping, Gliding, Liquid Simplification, Cluster Reduction, Weak Syllable Deletion, etc. These perfectly normal phonological processes persist for longer in many children with Speech Sound Disorders, and of course this is not considered to be ‘normal’.


Phonology is a branch of Linguistics and is the study of the speech sound system. Speech pathologists refer to ‘his phonology’ or ‘her phonology’ when talking about a child’s phonological system.

Place of Articulation<br />
Consonants are made by obstructing or constricting airflow at some point in the vocal tract. The point of obstruction or constriction is called the place of articulation. The ‘places’ of articulation are Bilabial, Labiodental, Interdental, Alveolar, Palatal, Velar and Glottal. Note that there are other classification systems that differ slightly.

Place-Voice-Manner (PVM)
Consonants are classified in terms of their place of articulation, manner of articulation and voicing.
Place-Voice-Manner Chart; PVM Chart
The chart is a PVM Chart showing the consonants of English. The voiced glide /w/ is included twice because it has two places of articulation, bilabial and velar. The glottal stop is also there because it occurs in some dialects (varieties) of English.

Plosive<br />
See the Glossary entry for Stops

Polysyllabic words
Some experts define ‘polysyllabic words’ as words of more than one syllable, and others define them as words of more than two syllables. There is a tendency nowadays, however, to avoid the ambiguous terms ‘polysyllabic words’ and ‘multisyllabic words’, preferring ‘one syllable words’, ‘two syllable words’ and ‘long words’ instead. See the Glossary entries for Long words and Multisyllabic words.

Pragmatics is the area of language function that embraces the use of language in social contexts: knowing what to say, how to say it, and when to say it – and how to ‘be’ with other people. Many children with pragmatic difficulties have unusual prosody and problems with knowing exactly how to modulate both voice and speech.<br />

Prosody; Prosodic features
Prosody is an essential aspect of speech. Prosody or prosodic features are added to the sequences of speech sounds. These features include pitch, intonation (the rise and fall of the pitch of the voice), stress (emphasis), rhythm, voice quality, loudness and rate.

Refer; Referral; Referring<br />
When a professional identifies a student with a potential problem with communication, literacy or swallowing they refer the student for a Speech-Language Pathology Assessment / Speech and Language Therapy Assessment. They describe their concerns in simple language (usually in writing) and talk to the student’s parent/caregiver about the need for ‘referral for assessment’, helping them find an appropriate SLP/SLT.
The information and insights that teachers or health professionals provide to the SLP/SLT in the course of referral and also in ‘case discussion’ can be very helpful.

Relational Analysis

See the Glossary entry for Core Speech Assessment Battery

‘Screening’ has at least three distinct meanings.
1. Early identification screening of at risk populations
a public health process in which children within a defined population; low birth weight infants; all pre-schoolers are tested to identify those who are at risk of speech and language problems so they can be referred for further diagnostic testing. The aim of such screening is to provide early identification, so as to provide treatment at the earliest appropriate opportunity or as a preventative measure.

2. Informal Speech-Language Pathology / Speech and Language Therapy triage screening
part of the initial assessment process carried out by a speech-language pathologist. The experienced speech pathologist makes judgements about the priority status of each newly referred child in order to make best use of resources and monitor the urgency and needs of those being referred.

3. Formal screening assessment

Screening assessments are used to decide whether an aspect of speech and language requires further investigation. For example, the screening assessment of the DEAP allows the therapist to gain a quick overview of the child’s articulation and phonology in order to establish whether or not to carry out full diagnostic testing.
The first type of screening described above is a public health role, to be carried out by health and education professionals including preschool and school teachers.

Selectively mute children

Selectively mute children can speak but only do so with certain people or in certain places; a child might speak at home to his/her parents but not to anyone at school (including his/her parents). A selectively mute child has an anxiety disorder and appropriate management is by a clinical psychologist or child psychiatrist. Many such children also have communication disorders, so a SLP/SLT may be involved, working collaboratively with the child, family and other professionals including teachers.

See the Glossary entry for Approximant

Soft palate; Velum

The soft palate (velum) extends from the rear of the hard palate nearly to the back of the throat, terminating in the uvula.

Sonorants are consonants or vowels produced without obstruction of the airstream (cf. Obstruent)

Speech Banana

‘Speech banana’ is a term used to refer to the speech spectrum since speech is softest in both the very low and high frequencies and loudest at low-mid frequencies, producing a banana shape when plotted on the audiogram (see the Glossary entry for Audiogramabove).

Speech Pathologist

An Australian term for speech-language professionals whose professional association is called the Speech Pathology Association of Australia, generally referred to as Speech Pathology Australia (SPA). The general public in Australia often call Speech Pathologists ‘Speech Therapists’ and the service they provide, ‘Speech Therapy’.
‘A speech pathologist has been trained to assess and treat people who have a communication disability. Speech pathologists complete a degree at university which encompasses all aspects of communication including speech, writing, reading, signs, symbols and gestures. Speech pathologists also work with people who have difficulties swallowing food and drink.’ Speech Pathology Australia

Speech-Language Pathologist
professional associations in the US and Canada call their members Speech-Language Pathologists or Orthophonistes in French Canada. The general public may refer to them either as Speech Pathologists or Speech Therapists. For more information see the Glossary entry for Certificate of Clinical Competency (CCC) above.
Speech-Language Therapist; Speech and Language Therapist
The professional association in New Zealand calls its members Speech-Language Therapists, and the association in South Africa calls its members Speech Language Therapists.

Speech Sound Disorder; SSD
A Speech Sound Disorder (SSD) involves difficulty with and/or slowness in the development of a child’s speech. There are severalclassification systems associated with SSD.
SSD may be due to a genetically based linguistic processing deficit (60% of children with SSD); fluctuating conductive hearing loss/ ‘glue ear’ (30% of children with SSD); or a genetically transmitted deficit in speech motor control (10% of children with SSD). There is overlap between these areas (e.g., a child might have glue ear and a linguistic processing deficit).

Speech Sound
The speech sounds are vowels, diphthongs, triphthongs, and consonants.

Speech Sound System
Speech sound system is another name for the phonological system. It is a system of sound contrasts.


Stammering is a synonym for Stuttering (see the Glossary entry for Stuttering below) and is the more commonly used term in the UK.

-‘stimulable’ has meant that a consonant or vowel can be produced in isolation by a child, in direct imitation of an auditory and visual model with or without instructions, cues, imagery, feedback and encouragement.
We know that if a child is not stimulable for a sound there is poor probability of short-term progress with that sound. That is, the sound is unlikely to ‘spontaneously correct’ or magically ‘become stimulable’. Since the late 1990s the child phonology literature has encouraged clinicians to target non-stimulable sounds, because if a non-stimulable sound is made stimulable to two syllable positions, using our unique clinical skills, it is likely to be added to the child’s inventory, even without direct treatment (Miccio, Elbert & Forrest, 1999).
The stimulability of a sound to two syllable positions is sometimes referred to as ‘true stimulability’.

Stops; Plosives

‘The stops’, are /p/, /b/, /t/, /d/, /k/ and /ɡ/. The glottal stop /Ɂ/ is also a stop. The terms ‘plosive’ or ‘plosive consonant’ are synonyms.
The place-voice-manner (PVM) chart above shows four voiceless stops (bilabial, alveolar, velar and glottal) and three voiced stops bilabial, alveolar and velar).


Stopping is a phonological process (phonological pattern) in which a fricative is replaced by a stop (e.g., ‘sea’ pronounced as ‘tea’) or an affricate is replaced by a stop (e.g., ‘jig’ pronounced as ‘dig’).

Structural Processes
See the Glossary entry for Syllable Structure Process

Stuttering; Fluency disorder
Stuttering is a fluency disorder. Stuttering (called ‘stammering’ in the UK and parts of the US) disrupts the fluency of speech. Hence, ‘stutters’ are often referred to as ‘dysfluencies’ or ‘nonfluencies’. They may be in the form of prolongations, blocks or repetitions. One or any combination of these features may be present, consistently or variably. All children who stutter require assessment by a SLP/SLT.

Substitution Processes
See the Glossary entry for Systemic Process

Syllable Structure Process

Syllable Structure Processes/Structural Processes) are speech simplifications made by children in which the structure of a syllable or word changes.These phonological processes include the developmental processes of Reduplication, Final Consonant Deletion, Cluster Reduction and Weak Syllable Deletion, and the non-developmental patterns of Initial Consonant Deletion, Deletion of Unmarked Cluster Element, and Final Vowel Addition.

Syllable Trees
There are two ways of representing the contents of a syllable non-linearly:
1. Onset and rime (rhyme) syllable tree comprising
The onset: the initial consonant if any

The rime: the rest of the syllable

The Rime is further divided into

i. nucleus (the vowel or vowels
ii. coda (final consonant if any)

2. Mora syllable tree

The portion of the syllable that follows the onset consists of one or more moras.
Each mora is a unit of syllable time, or ‘weight’, and each one is a consonant (C) or a vowel (V). Typically the first mora of the syllable is a vowel. A diphthong is noted as two vowels (VV).
Onset and rime syllable tree
Mora Syllable Tree

Metrical Stress Syllable Tree

In a metrical stress syllable tree the word is broken up in to metrical feet with “S” indicating a strong syllable and “W” indicating a weak syllable.

Systemic Process

Systemic Processes (also called Substitution Processes) are speech simplifications made by children in which a consonant is replaced by a different (incorrect) consonant. Systemic processes include the developmental processes of Fronting (a front sound like /t/ replaces a back sound like /k/ so that ‘car’ is pronounced as ‘tar’), Stopping, Context Sensitive Voicing and Gliding, and the non-developmental processes of Backing, Denasalization, Devoicing of Stops, Systematic Sound Preference and Glottal Replacement where it is not dialectal.


The most important articulator for speech production is undoubtedly the tongue. During speech, the amazing range of well-controlled movements the tongue can make includes tip-elevation, grooving, and protrusion. The tongue is almost entirely composed of muscle tissue. The parts of the tongue are the tip, front (the widest part), back (from the back teeth to the pharynx), and root (where it joins the lower jaw). It is anchored underneath by the lingual fraenulum.

Tongue-tie; Ankyloglossia
A tongue-tie (Ankyloglossia / Short fraenulum / Short fraenum) is a birth defect in which the lingual fraenulum, a band of tissue under the tongue, anchors the tongue too tightly from below so that the tongue has a ‘W’ appearance when the affected person tries to protrude it.
Tongue-tie may or may not affect speech, but all tongue ties should be checked by a SLP/SLT.


A triphthong is like a 3-part vowel containing a glide from one vowel quality to another, to another, as in the word ‘power’ (pow-oo-uh).


Tympanography is used to monitor otitis media with effusion (‘glue ear’). It is a measure of energy transmission through the middle ear, and the results are represented as a tracing on a tympanogram.

Velar; ‘The Velars’
Velar consonants, usually called ‘the velars’ are made at the velar place of articulation. There are three velars in English: /k/ as in ‘key’, /ɡ/ as in ‘go’ and /ŋ/ as in the final sound in ‘wing’.


See the Glossary entry for Soft Palate

Velar fronting
Velar fronting is a phonological process (phonological pattern) in which a velar consonant /k/, /ɡ/ or /ŋ/ is replaced by an alveolar consonant. So ‘colour’ sounds like ‘tulla’, ‘guy’ sounds like ‘dye’ and ‘wing’ sounds like ‘win’.

Vocal cords; Vocal folds
The vocal cords (or vocal folds) are composed of twin bands of mucous membrane stretched horizontally inside the larynx (voice box). They vibrate when we speak modulating the airflow from the lungs during phonation. Phonation refers to the production of sound by the cords. The sound itself is very quiet, but it is amplified by the resonators (cavities) it the head, neck and chest.

Vocal nodule; ‘Nodules’

A vocal cord nodule is a mass of benign tissue that grows on the vocal folds (vocal cords) affecting the sound of an affected person’s voice. ‘Nodules’ are common in young children, and young adult females (particularly teachers and singers).

Vocal tract

The vocal tract comprises the air passages from above the larynx to the lips and from above the larynx to the nostrils.


Voice is the sound produced by the vocal cords.

Voice disorder

Voice disorders are medical conditions affecting the production of the voice. Speech-language pathologists do not assess or treat people with voice disorders until the person’s larynx has been inspected by an Ear Nose and Throat (ENT) specialist.

Voiced consonants

A voiced consonant is made with vibration of the vocal cords. On a consonant chart (see below) they appear in the right hand position in a cell.

Voiceless consonants

A voiceless consonant is made without vibration of the vocal cords. On a consonant chart they appear in the left hand position in a cell.

In speech, vowels are the class of sound which makes the least obstruction to the air stream. All vowels are voiced (made with vibration of the vocal cords) and all are sonorants.

Vowel chart; Vowel diagram

The most familiar vowel chart is the one provided by the IPA. The ‘front’, ‘central’ (or middle) and ‘back’ positions on the chart refer to the front, middle and back of the tongue.
Close, mid-close, open-mid and open refer to how high the tongue is elevated in the mouth for the production of a particular vowel. A ‘close’ or ‘high’ vowel sees the tongue high in the mouth and the jaw comparatively closed. An ‘open’ or ‘low’ vowel sees the tongue low in the mouth with the jaw comparatively open.
The chart does not show the three lip positions for vowel production, namely: rounded, neutral or spread.

Vowel Chart IPA 2005
Vowel Chart SIL
Weak Syllable Deletion
Weak Syllable Deletion
is a phonological process (phonological pattern) in which the weakly stressed syllables in words are omitted; for example, ‘effant’ for ‘elephant’, ‘stake’ for ‘mistake’ and ‘member’ for ‘remember’.
Within Normal Limits; WNL
The term ‘within normal limits’, always abbreviated WNL, is used to indicate that no abnormal results were found during the testing of an individual child or adult. Another way of saying WNL in children is to report that a child’s performance when tested was ‘age appropriate’ or that the child’s results ‘fell within typical age expectations’.

Speech and Language Therapy training

Excitedly, I have finished studying a short course ‘ELKAN Speech and Language Support learners aged 11-16’s’ during which I compiled a portfolio with the view to gaining a qualification from ELKAN, in this field of study.

I hope that during and afterwards I will be able to support the children I work with more effectively and support colleagues as well.

In schools, Speech and language support training for Teachers and Assistants are specifically designed to help practitioners including Support Assistants to understand the processes involved and how to apply practical strategies in the classroom. After the initial fundamental course, for those who work with children in either Primary or Secondary Schools, they can go on to do the specialist courses such as working with children with unclear speech or verbal children with ASD. The majority of learners report that it helps with all the children with whom they come into contact.

I am participating in an ELKAN practical training course which is for staff working in secondary schools.I hope that in undertaking this course I have previous knowledge and understanding consolidated. In addition I hope to gain new strategies and approaches to enable and empower me to maximise each student’s ‘speech, language and communication’ potential. I will do this by developing my ability and knowledge further to effectively differentiate the curriculum. The Education system in the UK is changing, it must as many children have Speech and Language difficulties either due to other Special Educational Needs and Disabilities (SEND) or the children have English as an Additional Language (EAL).

My course is delivered by two local tutors who work in one of the local secondary schools who have a resource base which they use to effectively support students daily. I will attend my course for ten sessions fortnightly however it can be delivered over ten weekly sessions, or as an intensive three day programme! The individual sessions lasts approximately two hours and includes interactive teaching methods, practical activities, videos and group discussion to engage learners and enable us to complete the portfolio tasks with time also to ask and discuss with our tutors.

This course is available throughout the UK so many other school staff can undertake this too – just ask your SENCO as the course is for SENCO’s, secondary school teachers, teaching assistants and speech and language therapy assistants.

There are also a wide range of other courses even for parents and family to support their child just visit the ELKAN website:

When I complete my course which includes my submitted portfolio of evidence then (I hope to) I will receive a Level 3 or Level 2 Award in Knowledge and Practice to Support the Communication Skills of 11-16’s – QCF acknowledged.

School staff need training and not only teachers, support assistants but even administrators, caterers and cleaners need to know how to communicate effectively with children who have speech and language difficulties or delays.

Speech and Language therapists assist children and adults who have the following types of problems:

  • difficulty producing and using speech

  • difficulty understanding language

  • difficulty using language

  • difficulty with feeding, chewing or swallowing

  • a stammer

  • a voice problem.

Little gems (quotes)


Every action in our lives tou

ches on some chord that will vibrate in eternity.

~Edwin Hubbel Chapin


The world is hugged by the faithful arms of volunteers.

~Everett Mámor


“Give me where to stand, and I will move the earth.”



“One of the secrets of life is to make stepp

ing stones out of stumbling blocks.”

Jack Penn

Tru3 J0y

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National Autistic Society helpline


Accept difference. Not indifference.

We are the leading UK charity for people with autism (including Asperger syndrome) and their families. We provide information, support and pioneering services, and campaign for a better world for people with autism. Our work relies on your support, so please get involved or donate today.

Autism Helpline

Tel: 0808 800 4104
(open 10.00am-4.00pm, Monday-Friday)

Text: 07903 200 200

Minicom service: 0845 070 4003

Email enquiry service: visit

and complete the online form

The Autism Helpline provides impartial, confidential information, advice and support for people with autism spectrum disorders their families.

The challenging behaviours which children with autism display

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The challenging behaviours which children with autism display as well as the possible reasons for these behaviours, with some helpful ideas about different ways in dealing with the challenging behaviours.

Challenging behaviour by any child can be extremely difficult to cope with, however this difficulty increases with a child who has an autism spectrum disorder (ASD). Increasingly more difficult to cope with when your child is non-verbal. Challenging behaviour may be what would typically be considered physically aggressive behaviour, but also include behaviours like pica (putting inedible items in the mouth) and hand flapping if they are having a negative impact on your child or your family. Therefore, support which focuses on ‘Coping with challenging behaviour’ can be used alongside ‘Understanding behaviours’ and ‘Behaviour guidelines.’

It is important to know that behaviour has a function and that there could be any number of reasons for it and may include:
– difficulty in processing information,
– unstructured time,
– over-sensitivity (hyper)
– under-sensitivity (hypo) to something,
– a change in routine or physical reasons like feeling unwell, tired or hungry.
However being unable to communicate these difficulties can lead to further anxiety, anger and frustration, and then to an outburst of challenging behaviour.

It is extremely useful to set up a diary to identify behaviour triggers and to see if a pattern emerges. This involves writing down what was happening before the behaviour, the behaviour itself and what happened immediately after it. It is important to note the environment around your child before, during and after the behaviour, including who was there, any change in the environment and how your child was feeling. That way, you will be able to find the cause or the function of the behaviour and try to prevent it from happening in future.

Typically challenging behaviour, the possible reasons for it and some suggested strategies for addressing it:

Pinching, kicking, slapping
– frustration at not being able to communicate
– difficulty waiting for something, because of difficulty with concept of time and abstract thinking
– an unfamiliar person
– a change in routine
– over-sensitivity to noise, crowds, smells, touch, sight
– under-sensitivity – seeking out sensory input from pinching or slapping
– feeling unwell, tired, hungry, thirsty, uncomfortable
– not wanting to do something.

Suggested strategies:
– use the Picture Exchange Communication System (PECS) and/or visual supports to help with communication and show your child the sequence of events and routine for the day
– prepare for meeting unfamiliar people by showing photographs of them and introducing them in small stages. Tell your child when they will see them, using visual support
– prepare for any changes in routine
– use ear defenders to block out noise and sunglasses to reduce light, and reduce strong smells, replacing them with smells that your child prefers
– create opportunities for sensory stimulation, eg pinching play-dough, clapping hands, singing a clapping song/rhyme, kicking a football or punch bag
– reward your child for doing something they don’t want to do, straight after the desirable behaviour
– say in a calm, monotone voice, without showing emotion: “(Child’s name) hands down/feet down. No pinching, slapping, kicking” and then redirect them.

– fear of toilets or public/new toilets
– feeling unwell
– in pain
– reluctant to wipe because toilet paper may be too uncomfortable
– seeking out sensation from texture, smell or movement of arms during smearing action
attention seeking/wanting a reaction
– not knowing where faeces needs to go.

– provide an alternative with the same texture, eg papier-mâché, gelibaf, gloop (cornflour and water), finger painting, play-dough, etc
– make a structured timetable of the day, showing times when your child can do appropriate smearing activities
– take your child to the GP to make sure that there are no physical reasons involved, like being in pain
– if your child does not understand the wiping process, teach them ‘hand over hand’
– if the toilet paper is too harsh for your child’s sensitive skin, wet wipes could be a gentler alternative
– avoid asking your child to clear up after themselves, as they may interpret this as being a reward
– avoid paying too much attention or showing too much reaction
– do not tell them off, as this can be seen as reinforcement of the behaviour
– use minimal interaction and alternative cleaning-up methods, like baby wipes or a tepid shower
– set up a toileting routine
– use ‘all-in-one’ suits.

– enjoys the reaction from an adult or another child around them
– looking for attention/interaction
– difficulty swallowing and/or may be producing too much saliva
– likes to play with the saliva and enjoys the way it feels
– uses the behaviour to avoid doing something.

– take your child to the GP and/or dentist to rule out any medical reasons
– avoid making eye contact with your child
– play this behaviour down as much as possible
– limit verbal communication
– wipe away the saliva as soon as it happens
– do not give your child attention
– redirect them to a more appropriate activity
– provide alternative sensory activites, eg water play, finger painting, etc
– give your child lots of positive attention for doing a more appropriate activity
– give them a sweet or something to suck to keep their mouth busy
– make sure they understand what is expected and redirect them using a visual timetable.

Hair pulling
– seeking out a reaction from an adult
– looking for attention
– having difficulty meeting new and unfamiliar people
– seeking out or avoiding a sensory input, eg the smell of the person or the noises they make.

– tie long hair back
– avoid giving your child a reaction
– do not talk to them
– do not make eye contact
– distract them by, eg, tickling them or giving positive reinforcement
– redirect them to a more appropriate activity
– prepare your child when introducing them to unfamiliar people
– give opportunities to satisfy the pulling sensation they may enjoy, such as ‘row your boat’ game, tug of war, climbing up a rope, etc to suit their age, ability and interests.

– looking for attention
– seeking out sensory input to the mouth
– frustration at not being able to communicate something that is causing distress and to get it to stop, or struggling to get needs met
– reacting to something going on in the environment, eg too much noise
– pain in the mouth or teeth.

– rule out any medical or dental reasons for the biting
– improve communication: “(Child’s name), no biting”
– use PECS and visual supports – use a ‘no biting’ symbol and a picture symbol showing what to do instead of biting
– increase structured activities
– reduce noise levels or other sensory stimuli that your child could find upsetting
– provide alternative things to bite, eg chewy tubes (see our ‘Biting’ information sheet)
– look at anger/emotions management and create opportunities for your child to relax
redirect them to a more appropriate activity
– reward appropriate behaviour, eg “(Child’s name), that’s good sharing with your sister”, and give a reward as soon as you see appropriate behaviour, to encourage it to continue.

– not understanding which items are edible and inedible
– seeking out sensory input – the texture or the taste of the item
– relieving anxiety or stress
– seeking attention
– getting out of doing something.

– replace the inappropriate item with an appropriate alternative of a similar texture, eg a crunchy carrot stick if your child chews on things like stones or sticks
– provide other forms of stimulation for the mouth, eg chewy tubes, popcorn, chewing gum, etc
– set up a sorting activity for your child to sort edible and inedible items
– take your child to the GP to rule out any medical problems or pain in the mouth
– consider any vitamin or mineral deficiencies
– reward your child for putting edible items in their mouth
– use PECS to encourage your child to put appropriate items in their mouth and reward them
increase the amount of structured activities your child does and distract and divert their attention.

Further concerns on challenging behaviour can be found through the National Autistic Society.

Autism spectrum disorders and genetics

Autism is a complex neurodevelopmental disorder, marked by multiple symptoms that include atypicalities in:

social interactions – people with autism would often find it difficult to understand others’ mental states and emotions, and respond accordingly
verbal and non-verbal communication
repetitive behaviour – people with autism might repeat certain words or actions over and over, usually in a rigid rule-governed manner).

The degree to which these symptoms manifest themselves varies greatly, leading to the use of the term ‘autism spectrum disorders’ (ASD). ‘Autism’, as originally described by Leo Kanner in 1943, represents an extreme end of the spectrum, often marked by severe impairments in one or more of these three domains described above, other manifestations of these symptoms are sometimes associated with diagnostic labels such as ‘Asperger syndrome’, ‘atypical autism’ or ‘pervasive developmental disorder – not otherwise specified (PDD-NOS)’. All of these are sometimes referred to as ASD, or ‘autism spectrum conditions’ (ASC).

Early twin studies showed that Kanner’s autism was highly heritable, which suggests that there is a considerable genetic component to this condition. This represented a major shift in the then dominant models, which speculated autism to be largely a product of one’s environment and upbringing. The genetic component was further supported by a series of later findings that ASD runs in families. Autistic traits are highly heritable, suggests that if a twin had a very low score on a specific autistic trait (e.g. social behaviour as measured by a questionnaire), then the chance that the other monozygotic (MZ) twin would also have a very low score was very high, and vice versa for high scores. All of these studies provide support for the premise that there is a strong genetic element in the development of ASD and autistic traits. An increasingly popular view among mental health researchers is that complex conditions such as autism are best conceptualised within a dimensional framework, ie as extremes of traits that are distributed normatively within the general population.

Personally, I have observed families with twins who are non-identical and siblings are different and may not have notable autistic traits while a twin or sibling does and the following information on inheritance may explain this more scientifically – if you are less concerned with the specifics then please read over to maintain the gist of the scientific reasoning.


A key way to determine if a particular condition has a genetic basis, is to explore the similarities and differences among identical twins (monozygotic, ie from the same fertilized egg) and non-identical/fraternal twins (dizygotic, i.e. from two different fertilised eggs). A measure of genetic contribution that is calculated by comparing the proportion of monozygotic (MZ) twins that share a particular condition, with that of dizygotic (DZ) twins that share the condition. Statistically, heritability refers to the proportion of the variance in a particular phenotype that is explained by purely genetic effects and is estimated after accounting for phenotypic variance due to shared and non-shared environments. A condition with a high heritability (usually greater than 50%) is believed to have a strong genetic basis, while one with a low heritability is associated with low/moderate genetic basis.

Recent studies, however, have highlighted an important difference in the types of families that have members with ASD. There are some families where only one member has a diagnosis of ASD, and no one in the extended family has a diagnosis. Such ‘one-off’ incidences of autism are referred to as ‘simplex’ autism. Recent research suggests that some of these might be due to ‘de novo’ changes in DNA sequence, a rare sequence variant or a copy number variation, ie a one-off change that happens during the formation of gametes. It is believed that these rare variants can account for nearly 10% of all people diagnosed with ASD. On the other hand, there is a multitude of families, where more than one member of the extended family has a diagnosis, or several members have very high levels of autistic traits – even though they might have never received a formal clinical diagnosis. Such families are referred to as ‘multiplex’ families. It is believed that there are specific genetic variations, passed down through generations, that might underlie the increased incidence of ASD in these families.

Another increasingly important distinction in the genetics of autism is that between ‘syndromic’ and ‘non-syndromic’ (or idiopathic) autism. ‘Non-syndromic autism’ is a term used to describe cases where autism is the primary diagnosis – and not secondary to an existing condition caused by a well-known genetic variant, such as Rett syndrome, Fragile X syndrome, tuberous sclerosis, and the Smith-Lemli-Opitz syndrome. While we are far from developing a diagnostic genetic test for ASD, it is possible to check for a number of these known variants using standardised techniques. This has led to the suggestion that some of these conditions could potentially be included in a checklist of genetic testing of people with ASD.

Genes: Specific sequences of nucleotides (e.g. A/T/C/G) along a molecule of DNA which represent functional units of heredity.
Genome: The genetic complement of an organism, including all of its genes, as represented in its DNA.
Chromosome: In the context of human cells, a chromosome is a structure that consists of or contains DNA which carries the genetic information essential to the cell. Human cells have 23 pairs of chromosomes, 22 of which are nearly identical to each other (autosomes). The 23rd pair consists of sex chromosomes, and are non-identical for males (who have X and Y chromosomes), but nearly identical for females (who have two X chromosomes).
Phenotype: The outward appearance of the individual. It is the product of interactions between genes, and between the genotype and the environment. In humans, a phenotype could constitute a wide variety of observables, from a bodily feature (e.g. brain structure) to a measurable behaviour.
Genotype: The genetic constitution of the individual; the characterisation of the genes.