Lecture 2: Identifying Atypical Development

atypical development

• the extremes of individual differences in development 

-statistical deviation from the norm

-includes advanced and delayed development

-associated with neurodevelopmental conditions

difficulties with defining atypical development

• individual differences in the rate of development

• individual differences in people’s traits, strengths and weaknesses

typical development

-normal ability level at start

-increases and progresses with age

delayed development

-gap between this and normal development

-gap continues to grow as age increases

-child has weaker abilities than normal development

delayed development with catch up

-starts at same ability level as normal development

-as child gets older there is some delay in ability levels

-catches up in ability as time passes → delay is resolved

lower starting point development

-child’s development starts from a much lower point to begin with than normal development

-develops at same rate as a typically developed child

-never catches up to ability level as started at a much lower ability level

advanced development

-starts at same ability point as normal development

-rapid growth at a much faster rate than expected of a typical child

-maintains this stronger ability over time

different patterns of atypical development

developmental regression

-period where a particular skill is developing along a typical trajectory → but then child stops developing and loses aspects of this skill 

-typically seen is ASC and/or intellectual disability 

-most often language and motor skills 

multiple domains of development

-adaptive behaviour

-social

-cognitive

-physical

-motor skills

adaptive behaviour (domain of development)

• ability to work

• functional decision making

• personal safety

• managing money

• personal responsibility

• independence

• daily living skills

social (domain of development)

• gestures

• reciprocal eye contact

• empathy

• verbal communication

• social interactions

• non-verbal communication

• turn-taking

• emotional IQ

cognitive (domain of development)

• IQ

• attention

• language

• executive function

• numerical ability

• memory

physical (domain of development)

• facial dysmorphism 

• microcephaly 

• macrocephaly 

• physical features 

motor skills (domain of development)

• fine/gross motor skills

• balance

• coordination

• activity level

normal distribution 

-obtained by testing many participants 

-for may variables samples from the population generate a normal distribution 

-bell shaped curve

identifying atypical development

-group comparisons against a representative sample

-choose appropriate control group

profile of child’s abilities

-understanding of child’s abilities cannot be built without identifying strengths and weaknesses

-strengths can be subjective or relative:

• something they’re good at compared to other skills

• not necessarily a strength compared to other people

specific experimental design (cognition - measuring development)

 -investigate a specific research question or hypothesis, target specific behaviours 

-format can vary widely depending on the research question and methodology 

-can compare results with a matched control group 

standardised tests (cognition - measuring development)

-designed to measure knowledge or skills in a consistent and comparable way across a large population

-fixed format with specific instructions, questions and scoring procedures

-scores can be standardised → given a value that indicated how well they performed against everyone who has taken the test

comparing specific and standardised tests

-standardised tests aim to measure broader knowledge or skills → experiments aim to test a specific skill or test hypothesis

-standardised tests are broad, covering a range of topics or skills → experiments focus on specific research question 

-standardised tests aim to generalise results to a larger population → experiments have limited generalisability depending on sample and conditions 

Wechsler Intelligence Scale for Children (WISC)

-widely used intelligence test

-aged 6-16

-measures:

• verbal comprehension index

• fluid reasoning index

• visual spatial index

• processing speed index

• working memory index

verbal comprehension index (WISC)

-measures a child’s ability to understand and use language and their verbal reasoning skills 

visual spatial index (WISC)

-measures ability to perceive, analyse and manipulate visual information 

fluid reasoning index (WISC)

-measures ability to solve novel problems and think flexibly

-abstract reasoning

working memory index (WISC)

-measures ability to hold information in mind

processing speed index (WISC)

-measures ability to quickly and accurately process information

tasks of the WISC

-full test measures the Full Scale IQ (FSIQ), which is split into: 

• performance IQ (PIQ)

• verbal IQ (VIQ)

Vineland Adaptive Behaviour Scales (measuring development - adaptive behaviour)

-semi-structured interview carried out with parent/caregiver/teacher 

-measures: 

• communication 

• daily living skills 

• socialisation 

• motor skills 

• maladaptive behaviour

Wechsler Nonverbal Scale of Ability (tests for non-verbal participants)

-assesses non-verbal reasoning and problem solving skills

-aged 4-21

-uses visual stimuli and requires minimal verbal instructions

Leiter International Performance Scale (tests for non-verbal participants)

-assesses cognitive abilities

-aged 3-75

-matching pictures, completing patterns, solving mazes → assess different aspects of intelligence

-useful for assessing those with autism, language impairments or hearing impairments 

Bayley Scales of Infant and Toddler Development (tests for younger participants)

-aged 1-42 months

-cognitive, motor, language, social-emotional and adaptive behaviour

-observation of motor skills, tests of cognition and social interaction

Infant-Toddler Developmental Assessment (tests for younger participants)

-birth to 36 months

-those at risk of developmental delays or conditions

-cognitive, motor, language, social-emotional, and adaptive behaviour

-observation, parental report and standardised tasks

-often used in early intervention programs to identify those who require additional support

standardised scores (interpreting task performance)

-add scores together to create raw score

-convert raw score to standardised score

-this converts the raw score to a value that represents how a participant has performed to others of the same age/gender

-removes individual differences and generates a score that can be compared across participants

look-up table (interpreting task performance)

-after completing a test and obtaining a raw score, experimenter can use a look-up table based on appropriate representative sample to identify a scaled score

-can create a standardised score by making raw score into t-score

benefits of using standardised scores (interpreting task performance)

-enables clinicians to standardise performance across different groups 

-provide a common language for discussing test performance regardless of how the actual test is designed 

-easily interpretable 

-no one set way of standardising but all allow the same comparison