RESEARCH IN
DEVELOPMENTAL PSYCHOLOGY
*All Research entails:
--Theory: an overarching set of
assumptions & explanations which helps to
guide research
e.g., Psychoanalytic theory; Theory
of Natural Selection
--Hypothesis: a testable prediction
Two-tailed: “Breast-fed infants will differ from
formula-fed infants on frequency of ear
infections."
One-tailed: “Breast-fed infants will have fewer
ear infections than formula-fed infants.”
--Operational Definitions: measurable
behaviors used, for the purposes of that
experiment, to define some concept/variable
e.g.,“Intelligence is what an I.Q. test
measures.”
--Sampling of a Population
Random sampling vs. unbiased
sampling
I. Descriptional & Correlational
Research
*CANNOT infer cause-effect
*No manipulation of variables
–includes Naturalistic Observation,
Case Studies, Survey/Self-Report, etc.
--Correlational Research assesses the
relationship between two (or more)
variables, based either on an active study,
or archival material (e.g., the U.S. Census)
Correlation Coefficients have 2 parts:
a. number, from 0.00 to 1.00
b. sign: positive or negative
(neg. a.k.a. inverse)
--Number indicates strength of the
relationship:
0.00 - 0.29 weak relationship
0.30 - 0.69 moderate
0.70 - 1.00 strong
--Sign indicates direction of
relationship:
Positive means high X, high Y, etc.
Negative means low X, high Y and
vice versa
II. Regression Analyses
--statistical technique that examines the
relationship between a dependent/
response variable and multiple
independent / explanatory variables
For example, NICHD day care study
examined whether attachment of child to
mother most affected by:
--number of hours day care/week
--age at which child began day care
--responsiveness of mother
--sex of child
--demographic factors
III. Experimental Research
*CAN infer cause-effect, because
isolation of causal variables:
--manipulate potentially causal variables
--control potentially confounding
variables
A. Laboratory Research
1. Types of Variables
Independent: what experimenter
manipulates (or manipulates levels of)
Dependent: behavior, etc. that is being
measured as a function of the independent
variable
Subject: any traits, variables that an
individual brings to the experiment, e.g.,
sex, birth order placement, I.Q., had a
working mother
Confounding: any variables which, because
of poor research design, or insufficient
control, may alter results
2. Between- vs. Within-subject designs
a. Between-Subject Design
--Experimental vs. Control groups
--random/unbiased assignment into
groups
b. Within-Subject Design (a.k.a.
Repeated Measures design)
--all subjects receive all
conditions
--counterbalance order of
conditions, to eliminate practice
& fatigue effects
c. Factorial Designs
--Two or more variables (may be
any combination of between,
within, or subject variables)
--allows detection both of main
effects and Interactions
COPE ratings are ratings of congressional votes. A high COPE rating indicates prolabor
votes. Each observation is a member of congress. Suppose that you want to determine if
COPE ratings vary by political party and by region of the country. You also want to test
for an interaction between region and party.
Assume two variables: PARTY & REGION
B. Field Experiments
1. Exactly the same as lab experiments,
but conducted in the field (a natural
setting)
WANTED: Undergraduates to
participate in a neuropsychology
experiment.
Participants will receive $2000 upon
completion of experiment.
The study involves severing some parts of
the brain to see what types of cognitive or
behavioral impairments occur. It is
expected that the findings will have
implications for cognitive science, and may
generate useful therapies for those who
have suffered strokes, etc.
IV. Quasi-Experimental Research
--cannot manipulate “independent”
variable because of ethical or practical
concerns
A. Standard Quasi-Experimental Designs
1. "Independent" variable is usually a
subject variable--sex, I.Q. level,
from divorced vs. intact family;
autistic children, brain-damaged,
lived through 9/11/01 in NYC
2. Participants cannot be randomly
assigned into groups
3. Dependent measures may still be
designed scientifically, control
of confounding variables, etc.
B. Developmental Research
1. Longitudinal: same subjects studied
over a period of time (even years)
Film Example: Seven Up! (Paul Almond),
Seven plus Seven (Michael Apted, henceforth),
Twenty-One, 28 Up; 35 Up, 42 Up, 49 Up
“Give me a child until he is seven and I
will give you the man.” -Francis Xavier
Upper Class Boys: John**, Charles*, Andrew
Upper Class Girl: Suzy
Working Class Girls: Jackie, Lynn, & Sue
Cockney Boy: Tony
Charity Home children: Paul, & Symon (only black
participant)
Yorkshire Lad: Nick
Neil (later suffers from mental illness)
Peter* (classmate of Neil’s; has dropped out)
Bruce
a. Pros:
-see patterns of individual
development
-fewer subjects needed
-each subject serves as his/her own
control (fewer confounding var.)
b. Cons:
-Non-representative sample
because:
a) Self-selection of those willing
to participate
b) Selective Attrition
c) Only a single age group might
be studied, leading to a
cross-generational problem
(results don’t transfer to
other generations)
-Age/History confound
(due to cultural or historical
events, not to age), e.g., favorite
decorating
colors
2. Cross-Sectional: Different age
groups (or cohorts) are compared on some
behavior
a. Pros:
--quick & less expensive
b. Cons:
--Cohort effects: results due to
social or historical backgrounds of
subjects in each cohort, not to
age/development
e.g., political beliefs on flag burning
of people at 20, 40, 60
3. Sequential: Combination of
longitudinal & cross-sectional techniques
used--several cohorts also studied
longitudinally
C. Ethics of Research
1. Informed Consent: people must
be given enough information
about what they (or their
children) are to do, to give
consent
2. Confidentiality: participants’
identities should not be revealed,
including identifying information
3. Protection from Harm:
researchers have the responsibility
to protect participants, and to \
minimize their discomfort whenever
possible
4. Benefits to Risk Ratio in approval
of research: is the potential benefit
to society or the individual is
sufficiently greater than the risk
to the individuals who participate
D. Summary Statistics
1. Mean: Average of a set of scores
or measurements
2. M______: Most frequently
occurring score or measurement
3. M_______: Middle score (after
scores have been rank ordered)
--When is each measure most
appropriate?