This document discusses developmental research and the longitudinal research design. Developmental research studies progressive changes that occur as organisms develop. The two main research designs are cross-sectional and longitudinal. A longitudinal study observes the same group of participants over time. For example, a study observed children's pretend play every 6 months for 3 years. Longitudinal research allows assessment of stability, identification of trends, and avoids cohort effects. However, it is time-consuming, expensive, and subject to attrition bias if participants drop out. The document then provides an example of a hypothetical longitudinal study that examines the development of self-inhibition in toddlers, children, and teens. Participants would be observed to see how many chocolate chips

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Developmental Research
Let's look at a baby. A baby doesn't really do much, doesn't seem to think much, and can be really kind of
boring to study on its own. A toddler is a little more interesting. It can talk, walk, and interact with its
environment. You can begin to assess some of the cognitive developments occurring. Kids in elementary
school develop quickly, and their skills grow exponentially. Take a moment to consider the differences
between the different developmental periods. How is a child cognitively different than an adult? How is a
teenager emotionally different than an elderly person? This continuum is the span of human development.
Developmental research is a study focused on the progressive changes that occur as an organism
develops. There isn't any way to reverse the changes that happen when you grow up. You can't take an
older person and hit the reset button to revert them back to childhood to see how raising them in a different
time will change who they are. It'd be nice, but unfortunately we are stuck experiencing time in one
direction.
As we just discussed, there are magnitudes of difference between a few years of growth. When looking at
individuals along this continuum, a researcher wants to know what changes occur. A scientist is not
satisfied knowing 'Things are different.' A researcher wants to know 'What is different?'
Methodology
How does a researcher go about and study the changes? The two primary ways are cross-sectional and
longitudinal, which we will more thoroughly explore in other lessons.
Before we get into examples on how this is done, we first need to have something to study. It sort of makes
sense, and I'm sorry I had to put it in, but it's where we have to start. Let's look at how self-inhibition
develops across a spectrum.
So we are going to look at self-inhibition, or the ability to tell yourself 'No!' We need to figure out how
we're going to study it. Well, I'm eating chocolate chips right now, so let's say we put a bowl of chocolate
chips in front of our participants and instruct them not to eat them.
Lastly, we need to figure out what age we are going to look at. Babies aren't really going to be useful in
this experiment, so we won't use them. So the youngest age we will look at is toddlers. And since we want
to know about development until adulthood, we will take everyone up to adulthood. We will be using
toddlers, kids, and teens.
Cross-Sectional
Cross-sectional studies are defined as comparing and contrasting samples of different age groups to
determine what difference occurs in each age group. In our example of studying inhibition, we will collect
participants from each age group. So we will have a group of children acting as representatives of their age
group. Here is how I will divide them; you could very easily do something different.
 Age 2 to 2.9
 Age 3 to 4.9
 Age 5 to 9.9
 Age 10 to 14.9
 Age 15 to 20
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'.9's' were used to ensure that each child would not belong to two groups. The researcher will follow the
same process with each individual in each group. The participant will sit down in the chair and be
instructed not to eat the chocolate chips. The researcher then leaves the room for 10 minutes while others
behind a two-way mirror count how many chips they eat.
A way of thinking of cross-sectional studies is you are taking a section from across a spectrum.
The Longitudinal Developmental Research Design
Developmental research designs are a type of nonexperimental research that can be used in order
to study age related changes in behaviour. One principal type of developmental research design
is the longitudinal design, in which one group of subjects are studied repeatedly over a period of
time. This week I am going to be describing this form of longitudinal design and outlining its
strengths and weaknesses.
Within a longitudinal developmental research design, the same participants are observed
recurrently over a period of time. This period of time may be quite brief (six months to a year), or
very long – sometimes even spanning a lifetime! The researcher may be studying one specific
aspect of development (for example, intelligence) or many. The subjects being studied are usually
cohort, which means they are roughly the same age and have grown up in similar circumstances.
The Longitudinal research design is an example of within-subjects design. However, no
treatment is administrated, instead the ‘treatment’ is the age. Longitudinal studies are often
described as a number of observations followed by a period of aging and development then
another set of observations.
One example of a longitudinal developmental study is that of Howes and Matheson (1992)1
, in
which the pretend play of a group of 1-to-2 year old children were repeatedly observed every 6
months over a period of 3 years. Howes and Matheson found that complexity of pretend play
increases with age and is also a reliable predictor of children’s future social competence with
peers.
There are several strengths and weaknesses associated with the longitudinal developmental
research design. Firstly, main advantage of the design is that it allows researchers to assess the
stability and continuity of several attributes of a sample by repeatedly observing the same
participants (Kagan & Moss, 1962)2
. Additionally, this type of design also allows researchers to
identify developmental trends by looking for common attributes that the subjects share, for
example, points at which most children undergo changes (Newman et al, 1997)3
. Another major
strength of the longitudinal design is that it avoids cohort effects because the researcher
examines one group of people over time, rather than comparing several different groups that
represent different ages and generations. Longitudinal research designs also allow researchers to
discuss how a single individual’s behaviour changes with age. Finally, this type of design
combines both qualitative and quantitative data, creating more in-depth research (Ruspini
1999)4
.
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Although so far I have portrayed the longitudinal research design in a positive and beneficial
manner, it is important to recognize its limitations and the disadvantages associated with using
this form of research design. Firstly, longitudinal research is very time consuming, for everyone
involved. The participants must be highly committed in order to continue and complete the
duration of the study, and the researcher must remain interested in the research whilst they wait
for years to see the final results. As well as being time consuming, this form of research is also
very expensive to conduct, since the researchers must track people down and persuade them to
come back and participate in the study. Additionally, there is added expense of repeatedly
training experimenters to conduct the study if it is going to span over many years. Also, focus of
the theory and research into the developmental sciences is constantly changing, thus longitudinal
studies may seem new and exciting to start with, but by the end of a 10 or 20 year project the
outcome may seem trivial.
Further disadvantages can be identified when assessing the validity of the longitudinal research
design. Practice effects may threaten the validity of a study: participants who are repeatedly
tested and interviewed may become increasingly familiar with contents. As a result, they may
display performance improvements that are unrelated to the normal patterns of development.
Furthermore, the longitudinal research design is subject to high drop out rates of participants,
which may also weaken the internal validity of such studies. A study conducted by Colby et al.
(1983)5
is one example of a longitudinal study to suffer participant attrition: participants were
interviewed at intervals of 3 to 4 years over a 20 year period and the sample size decreased from
84 participants to only 51. Since longitudinal studies may go on for a number of years,
participants may lose interest in the study, move away or die. When participants drop out of a
study, it is known as participant attrition, which can result in smaller and non-representative
samples. The participants who drop out may have different attributes as those who stay,
consequently, the group at the end of the study may have completely different characteristics as
the initial group at the beginning. For example, if the less-motivated participants drop out during
a study, the group of participants at the end will be more motivated than the group at the start
and this higher level of motivation may explain the changes made over time, rather than the age.
One final limitation of the longitudinal developmental research design is the cross-generational
problem. As I mentioned earlier, children in a longitudinal study are usually drawn from one
cohort, therefore they are likely to have very different experiences than children from other eras.
For example, consider how much change there has been since the 1940s and 1950s, when
children in some of the early longitudinal studies were growing up. Family dynamics have
changed drastically since then, and modern families are a lot smaller now, move houses more
frequently and often use day-care centers and nurseries. Children now have access to computers,
video games, and televisions, which were not available in the 1940s and 1950s. Children of earlier
eras grew up in a completely different world, so it cannot be certain that children today develop
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in exactly the same way. As a result, these cross-generational changes may limit the conclusions
of the longitudinal studies to only the participants growing up whilst the study was in progress.
In conclusion, in the longitudinal developmental research design, the same group of participants
are observed and measured at different intervals over a period of time, thus cohort effects are not
a problem. Stability, continuity and normative trends can easily be identified and quantitative
methods are combined with qualitative methods. However, I believe the weaknesses of this type
of research design outweigh the strengths. Longitudinal studies are very time consuming for both
researchers and participants, as well as being extremely expensive. The validity of such studies
can be questioned due to practice effects, and participant attrition may create biased and non-
representative samples. Finally, cross-generational problems can make it difficult to generalize
finding from studies between different eras. In all, researchers must take into account the many
disadvantages of using this type of research design before undertaking a study. However, these
disadvantages may be overcome by using a very similar research design called the sequential
design, which combines the best features of longitudinal research. I will discuss this design
further next time.
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The Development Studies major focuses on social transformation or change. The
problems of social transformation are urgent, massive, complex, and often transcend the
boundaries of conventional academic disciplines.
DS examines the problems, processes, and prospects for the development of human
and material resources in what are generally thought to be the less developed areas of
the world. To study comparative development effectively, one must draw upon many
disciplines and construct a balanced understanding of historical and contemporary
processes. Thus, studying development as a social transformation requires a blending of
knowledge and perspectives from political science, economics, sociology, psychology,
anthropology, geography, history, and environmental science.
Student Learning Goals
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Undergraduates should have the following knowledge and skills when
they graduate with a major in Development Studies from UC Berkeley:
Develop Strong Interdisciplinary Training with Control over Key Concepts in the
Social Sciences
 Develop a critical understanding of conventional and non-conventional measures
and indices of development
 Comprehend core concepts pertaining to Development Studies which are part of
larger social scientific traditions and analysis (state, market, civil society)
 Understand the genealogy of particular theoretical traditions of development that
are both rooted in and cross cut the disciplines.
 Grasp the complex relations between development as a series of planned
interventions (at various levels) and the dynamics, conflicts and rhythms of
historical change and social transformation.
Apply an Interdisciplinary Approach to the Analysis of International Development
Theory and Practice
 Recognize how differing concepts and ideas are translated into development
practice
 Identify the multiple forms of state and non-state interventions – and the map of
multilateral, bilateral and local development institutions – associated with
contemporary international development.
 Integrate understandings of market, state and civil society, and grasp how they are
deployed in development theory and practice
Acquire Historical & Geographical Knowledge and Language Skills
 Examine the historical processes by which the Global South emerged from within
the modern world system (post 1450)
 Develop a comparative understanding of major world regions and their interrelations
 Gain a substantive knowledge of cultural, political, economic, and historical
development of one particular region of the developing world; if possible, participate
in Education Abroad Program in a country in the region
 Acquire language skills relevant to regional expertise
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Demonstrate Research, Critical Reading, and Writing Skills
 Formulate well-organized arguments supported by evidence
 Write clearly and effectively
 Apply basic quantitative skills
 Critically evaluate arguments in professional, public and advocacy literatures
 Gain some practical experience through internships
Learning Goals Appendix:
DS Learning Goals: Appendix
Major Requirements
Lower Division:
5 Courses
 DS 10: Introduction to Development Studies. (You must earn a C or better prior to
declaring. This course can only be repeated once). DS 10 is restricted to freshmen,
sophomores, and first-semester junior transfer students. Continuing juniors or
seniors who have not taken DS 10 may substitute with any course listed in
Appendix B in the DS Handbook.
 Econ 1 or 2: Introduction to Economics. (You must earn a C or better prior to
declaring. This course may be repeated only once).
 Anthro 3: Introduction to Social and Cultural Anthropology.
 IAS 45: Survey of World History.
 Statistics 2, 20, or 21.
Foreign Language:
All students must demonstrate a proficiency equivalent to four college-level semesters in
any modern language other than English. Equivalency can be achieved through
coursework, AP credit, examination, and/or study abroad. For more information on how
to complete the language requirement, please consult the DS Handbook. Languages
accepted by the College of Letters and Science are not automatically accepted by the
DS major. Please check with the department for eligible languages.
Upper Division:
 Development Studies 100: History of Development and Underdevelopment.
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 Disciplinary Courses: two courses in the same discipline selected from Appendix A
in the DS Handbook.
 Development Courses: two courses selected from Appendix B in the DS Handbook.
 Methodology: one course selected from Appendix C in the DS Handbook.
 Concentration: three upper-division courses are selected to provide substantive
knowledge of the cultural, political, economic, and historical development of one
particular region of the developing world. It is best to choose courses from more
than one discipline. Concentration courses must be pre-approved by an advisor.
Courses are chosen from Appendix D in the DS Handbook.
How To Declare
Declaring:
Applications are accepted during the fall and spring semesters from the third week of
instruction until the last day of instruction (not the last day of finals). Applications are
accepted during the summer from the last week in May until the beginning of the fall
semester (not the beginning of classes).
To be eligible to declare students must have:
 completed DS 10 with a grade of C or better (students may repeat DS 10 only once
to achieve a grade of C or better);
 completed Economics 1 or 2 with a grade of C or better; and
 are not in the final semester of undergraduate work.
Additionally, students are encouraged – but not required – to complete two semesters of
college-level foreign language or the equivalent before applying to the major.
To get declared you must both:
 attend a Major Declaration Workshop (check the Teaching Program Calendar for
dates), and
 meet with an advisor to submit the DS application materials
Bring a completed DS Application – including all materials and transcripts listed below –
to the Workshop. Application materials may be submitted after attending the Major
Declaration Workshop. However, students will not be officially declared until they have
both attended a Workshop and submitted all declaration papers.
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