CHILD PSYCHOLOGY
Second Canadian Edition
Vasta, Younger, Adler, Miller, Ellis
Prepared by:
Mowei Liu
Chapter 2
Research Methods
Learning Objectives
• Learning Objective 2.1 Understand how
researchers use the scientific method to study child
development.
• Learning Objective 2.2 Compare and contrast the
research methods commonly used to study
children.
• Learning Objective 2.3 Analyze the strengths and
limitations of the four basic methods for studying
child development as a process.
Learning Objectives
• Learning Objective 2.4 Understand the uses of
cultural research, comparative research, and
psychophysiological methods.
• Learning Objective 2.5 Explain the ethical
guidelines for human research that developmental
researchers must follow.
Scientific Research
• Scientific method: rules for designing, conducting,
evaluating, and communicating research
– Theory: a set of statements that describe a relation
between behaviour and the factors that influence that
behaviour
– Hypothesis: a statement as to how one variable(s) may
influence another variable(s)
• High temperature conditions enhance aggression
– Law (Principle): a proven statement supported by strong
evidence
• Responses that produce satisfying consequences are
strengthened (Law of Effect)
Objectivity and Measurement
• The scientific method assumes objective
measurement
– Serves to eliminate bias
– Aims to operationalize the methods of study so that
other scientists can replicate the study (and
presumably replicate the research findings)
• Objectivity can be achieved by
– A focus on observable behaviours
– Ensuring that the behaviours under study are
precisely defined and are measurable
– Using a quantitative approach to measurement
Types of Research
• Descriptive research consists of conducting
observations or interviews and recording
responses
• Correlational research aims to describe the
association between two variables
• Experimental research aims to show a causal
relationship between one variable and another
Descriptive Research
• Observational methods
– Naturalistic observations vs. structured observations
– Limitations
• Observer bias: the influence of the observer’s
expectations and interpretations
• Observer influences: the effects of the observer’s
presence
Descriptive Research
• Interview methods
– Open-ended vs. structured
– Can provide a wealth of information
– Rely on the informant’s knowledge, memory and
ability or willingness to communicate
• Case studies
– Bring a wide range of information on one child
– Often are concerned with clinical issues
– Cautions need to be made when drawing
conclusions
Correlational Research
• A variable is any factor that can take on different
values
– E.g. running speed, intelligence quotients, gender
• A correlation is a statistical statement as to the
degree and direction of relationship between two
variables
– Positive: Values of one variable change in the same
direction (increase or decrease) as the other variable
– Negative: High values of one variable are
associated with low values of the other variable
Correlational Research
• The correlational coefficient “r” reflects the direction
and strength of a relation between two variables
– Ranges from -1 through 0 through +1
– Negative values reflect a negative relation
– Positive values reflect a positive relation
– The strength of the relation is indicated by the size
of the number: 0.5 is less strong than is 0.99
Correlations do not prove causality
Correlational Research
Figure 2.1 Scatter diagrams illustrating correlations between two variables. Each dot represents
one child and shows the child’s values for the two variables. One value is plotted from the vertical
axis and the other from the horizontal axis. The left two graphs show positive correlations, and the
right two graphs show negative correlations.
Correlational Research: Example
• A high positive r (0.78)
does not imply that
watching Sesame Street
causes improved reading
– only that the two
variables are related
• Suggests the need for an
experiment
Figure 2.2 A scatter diagram of a hypothetical correlation
between children’s viewing of Sesame Street and their reading
level. The correlation coefficient (r ) shows a strong positive
relation between the two variables.
Experimental Research
• Experiments offer the opportunity to prove causality,
i.e., manipulation of one variable induces change in
another variable
• Variables in an experiment:
– Independent variable (IV) is manipulated by the
experimenter and is assumed to be a causal factor
– Dependent variable (DV) is measured by the
experimenter and is assumed to be controlled by the
IV
Experimental Research:
An Example of a Group Study
• Hypothesis: Watching
Sesame Street improves
reading ability
• IV: Hours of watching
• DV: Reading level test
scores
• Four groups are asked to
watch either 2, 4, 8, or 10
hours per week
• Results: Increases in viewing
time lead to increases in
Figure 2.3 Sesame Street Viewing and Reading Test
reading level
Performance. Each bar shows the average test score for all
the children in that experimental group. What do these results
indicate about the relation between Sesame Street viewing
and reading ability? Why can we say from these findings that
viewing Sesame Street improves reading ability?
Experimental Research:
Other Experimental Designs
• Sometimes a group is not available for a study
– Study can be conducted using one subject
– Reversal Replication Design involves measuring the
DV under a baseline condition (phase A), instituting
the IV (Phase B), reverting back to the baseline
(Phase A), and then giving the IV to the subject a
second time (Phase B)
•A B A B
• Sometimes treatment CANNOT be reverted or
withdrawn
Reversal-Replication Design
Figure 2.4 A reversal-replication design showing a causal relation between the presence of
mother (the independent variable) and the amount an infant smiles (the dependent variable). The
third and fourth phases replicate the procedures and results of the first two phases.
Experimental Research:
Other Experimental Designs
• Sometimes variables can not be experimentally
manipulated
– Ethical concerns
– The nature of some independent variables (such as
cultural background)
– Quasi-experimental studies allow researchers to
compare groups differing on some important
characteristics
Studying Development
• Longitudinal studies measure a behaviour in the
same subject or group at different ages
• Advantages of longitudinal designs:
– Provide estimates of stability of behaviour over
time
– Estimate the impact of early experiences on later
behaviour
• Issues in longitudinal designs:
– Attrition of subjects over time
– Problems with repeated testing
– Measurement instruments become outdated
Studying Development
• Cross-sectional studies measure a behaviour in
different aged subjects at the same point in time
– Cross-sectional studies cannot tap into stability of
behaviour (because different subjects are used)
– Cohort effect: Different age groups have different
life experiences that may have a profound impact on
their behaviour
• Cross-sequential studies combine longitudinal and
cross-sectional designs
– Costly and time consuming
A Cross-Sequential Design
FIGURE 2.5 A cross-sequential design.
Children aged 4, 7, and 10 years are compared
cross-sectionally at Time 1 to reveal age
differences. Three years later, at Time 2,
another cross-sectional design is conducted
comparing these children who are now aged 7,
10, and 13. How might cohort effects play a role
in any differences found? To examine the
stability of competitiveness, each of the three
groups is examined longitudinally comparing
their scores at Time 2 to those at Time 1. How
could repeated testing affect the results?
Comparing the groups who were 7 and 10 at
Time 1 with those who are 7 and 10 at Time 2
allows the researcher to examine for a cohort
effect or a repeated testing effect.
Studying Development
• Microgenetic studies examine developmental
changes as they are occur
• Studies small numbers of children and administers
repeated measures at the time the developmental
change is expected to occur
– Costly
– Repeated assessment itself may cause change
Other Research Tactics
• Cross-cultural research examines a behaviour
under different cultural conditions, testing the
behaviour’s universality
• Comparative research examines a behaviour in
non-humans
– Avoids some ethical issues by doing research with
animals
• Effects of social isolation on maternal behaviour
• Psychophysiological methods examine
physiological activities associated with the
presentation of stimuli.
Ethical Issues
• Research studies must be conducted to avoid
– Physical or psychological injury
– Violations of privacy
• Through the use of peer reviews, subjects are
ensured of
– Informed consent
– Debriefing
– Anonymity and confidentiality
• Research conducted with animals must also
carefully follow ethical guidelines
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