Developmental Screening
and Assessment:
What Are We Thinking?
Glen P. Aylward, Ph.D., ABPP
Southern Illinois University
School of Medicine
Springfield, IL
Q 1: Is there a “Gold Standard”
in Developmental Evaluation?
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reference standard
Flynn effect (.3-.5 pt/year)
Bayley Scales (1969; 1993; 2006)
BSID—>BSID II (MDI 12 pts lower, PDI 7
points)
BSID-IIBSID-III (mental 6 pts higher;
motor 8 pts higher)
Mean 7 pt increase; comparability is
limited
Length/pragmatics
Q2: Is There Agreement as to
What Qualifies as a
Developmental Delay?
• “precision issue”
• 20% delay ?
• 2 standard deviations below the mean for
a reference group?
• Score compared to “local norms”?
• A ratio/criterion measure?
• Acceptance of psychometrically poor tests
• Recommend SD cutoffs
Q3: Does Development
(DQ)= Intelligence (IQ)?
• Neurologicmotorsensorimotor cognitive
• Skillfunctionintegrated functional unit
intelligence
• Complexity increases in concert with age
• Skill, function = potential
• Different streams, different rates
• Younger than age 2: simple cognitive
functions—only after discrete functions are
combined do we predict later “intelligence”
Canalized Behavior
• Species-specific, prewired, self-righting
• Fixed behavior pattern
• Not highly complex
• More canalized, less affected by adverse
circumstances
• Less canalized, weaker self-righting,
greater likelihood of disruption
• Sensorimotor behaviors are strongly
canalized
• Impact on test results/prediction
Integrated Functions
• Individual developmental skill/ability is not
most important
• Integration of abilities into functional units
that control these abilities
• Ability to integrate functionsinformation
processing, memory, discrimination,
attention
• Musicians [skills]section of orchestra
[function]integration of sections
(conductor) concert
IQ/DQ Ambiguity
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BSID-III
Mullen Scales
SB-V
K-ABC/2
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WPPSI-III
MSCA
DAS
Cattell
Cognitive Composite
Early Learning Composite
NVIQ, VIQ, FSIQ
Mental Processing Composite;
Mental Processing Index
FSIQ
General Cognitive Index (GCI)
General Cognitive Ability (GCA)
IQ
Q4: Is a Ratio DQ useful?
• Ratio DQ– MA/CA x 100
• Rate of development
• Not comparable at different age levels b/c
the standard deviation (variance) of the
ratios does not remain constant
• CI’s vary tremendously
• Interpretation is difficult
• “MA” is totally dependent on test used
• Similar issues with “developmental age”
• Better to use 1.5, 2 SD < ‘average’
Q5: Is Caretaker Report
Sufficient for Developmental
Screening?
• AAP (2006) policy statement regarding
surveillance and screening
• 1/3 of developmental screening
instruments (excluding those targeting
ASD) were parent completed
• Earlier, parent report considered a Stage I
or “prescreening” technique
• Evolved to being considered comparable
to hands-on screening
• ? Evidence-based use
Caretaker Report
• Little is known as to how parent completed
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questionnaires are affected by: 1) child-related,
or 2) environmental variables
Accuracy depends on developmental area
assessed, population
? Different tests for different populations
How questions are answered (y/n, Likert, etc.)
Considerations:
-- Length, detail
-- Age range encompassed
-- Presence/absence of examples of behavior
-- Test behaviors or milestones
Caretaker Report
• Diamond & Squires (1993): current behaviors,
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recognition (vs recall), behaviors should occur
frequently, parents need skills to be able to
complete questionnaire
Screening risk status of infant most predictive of
agreement < 2-years; at 2, race (marker of SES)
predictive
Camp (2007) spectrum bias: better/worse
identification depends on base rates of problems
Items most predictive often are those with
poorer agreement (puzzle board, stacks 6
cubes)
Q6: How Problematic Are
Test Refusals?
• Behaviors have an impact: frequently negative
• More pronounced with younger children
• Possibilities: a) Declines to respond to any item;
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b) specific types of items, or c) stops when
items become too difficult
Occasional refusals—41% of young children
State of arousal, affect, motivation,
temperament, physiological issues
Score refusals as failures, prorate scores, or
consider testing to be invalid?
Test Refusals
• Potential causes:
--Reaction to poor underlying skills/attempt to
avoid failure
--Oppositional behavior
--Shyness, anxiety
--Temperament
--Poor attentional skills/high activity level
--Fatigue/malaise
--Temper displays/crying
--Parental behaviors
Test Refusals
• Verbal production tasks, gross motor
activities, end of testing
• More in children born at biologic risk, low
SES
• Those who refuse any aspect of testing
differ from those who refuse some items
or who refuse more difficult items
• High rates of refusal at one age associated
with similar behaviors at later ages
Test Refusals--Implications
• Those who refuse to comply often have
decreased scores in several areas of
function--untestable
• Risk for lower test scores and higher rates
of problems at ages 7-8 years in many
areas
• Source of clinical information
Q7: Is There a Role for
Qualitative Information?
• Not in place of quantitative; rather, in
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conjunction with
Causes for + finding: cognitive impairment,
emerging LD, language dysfunction,
environmental risk, testing issues, combination
Clinicians vs. technicians
Play-based ‘assessment’
Examples: form board; naming pictures,
stacking cubes
Training to task
Quality Control
Clinicians vs. Technicians
• Quality of assessment may be
compromised because of the questionable
proficiency of examiners
• Not clear who is qualified
– Conceptual and factual knowledge of normal
development
– Awareness of significance of pathognomonic
indicators
– Well versed in administration & scoring
– (speed, best response, stop, eliciting report)
Q8:What About Prediction?
• Prediction tells us if early alarm or reassurance
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has any basis
Prediction is difficult because:
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Rapid developmental change
Intervening variables (environmental, biologic)
Interventions (EI, medical, social)
Testing itself has impact on developmental trajectory
(observational effect)
Emergent, latent, delayed, deficient, disordered
Moving target
Aspects of tests used at T1 T2 Tn
Domain/area of development
Prediction
• Stable performance: high risk>low risk>
moderate risk
• How does one define prediction (copositivity/co-negativity; ORs, correlations)
• Time span/interval
• What predicts what?
– Single composite measure may not be
appropriate; sub-domains of function
Q9: Is There a Summary?
• Consider tests as reference standards; be
aware of psychometric issues
• Evaluation is a balance between concepts
and pragmatics
• Percent delay is not accurate; criterion
based, > 1.5, 2, 3 SDs below average
• Consider what can be assessed at
different ages (skill=capacity)
• Ratio DQ’s not accurate
• Serial screening/assessment
Summary
• We need to better understand strengths,
weaknesses, and variables that affect caretaker
report
• Consensus on test refusals: should we include,
prorate, or invalidate scores?
• Clinicians need to test
• Environment affects different skills and at
different times
• Wear sunscreen and eat fiber