hello there psychology students and welcome to the start of unit 3 for AP Psychology in this video we are going to review the different themes and research methods in developmental psychology now developmental psychology is a branch of psychology that focuses on how people grow and change throughout their lives developmental psychologists focus on how individuals physically grow how their cognitive skills change how the individual's emotional understanding evolves and how their social relationships and personality traits developed from infancy to old age researchers will often approach human development in two ways either chronological order or thematic issue chronological order focuses on how people develop in a sequence as they age here the research focuses on the different life stages an individual will go through such as infancy childhood adolescence and eventually adulthood you're going think of this like stages in a video game except for instead of leveling up you just kind of keep losing stamina over time as you age so actually maybe don't think of it that way thematic issues on the other hand focus on specific themes and topics that span across a person's life these different themes focus on different questions Andor issues that persist in an individual's life instead of the particular age of the individual questions such as are our behaviors and traits determined by our genetics or by our environment does development happen in a smooth continuous process or through a series of distinct stages or do our early personality traits continue throughout our life or do they change as we grow each of these questions represents one of three enduring themes that developmental psychologists often use to guide their research and theories the First theme is stability and change this theme explores how certain characteristics of an individual will remain constant over time While others evolve and change for example we can look at the denan multi-disciplinary health and development study in New Zealand which tracked people from birth to adulthood during the study they found that some personality traits remain stable While others often change due to an individual's life experiences this study is a longitudinal study which involves studying the same group of people over a long period of time you can think of longitudinal studies as the Netflix binge of research you're in it for the long haul watching all the episodes of someone's life as they unfold longitudinal studies are used to gain insight into changes and patterns that occur over an extended period of time these are great for tracking developmental changes understanding different Trends and patterns that exists over time and possibly even gaining insight into cause and effect relationships now while these studies are great at showing changes over time they do have some downsides for instance they are often quite costly to run they require a significant amount of time and resources and may suffer from patient attrition over time which just means that patients will drop out from the study before it is completed and now shifting gears back to our themes we can see our second theme is nature versus nurture which we last talked about in unit one remember when you hear the term nature think of heredity this is the predisposed characteristics that influence an individual's physical behavioral and mental traits and processes and when you hear the term nurture think of environment this is the external factors that an individual experiences such as a person's family friend group school and other societal factors psychologists exploring this theme are seeking to gain insight into how an individual's development is shaped by their genetics or environment today we can see that modern research suggests that it is both nature and nurture that play a role in the development of an individual studies such as the Minnesota study of twins reared apart another longitudinal study showed that even identical twins raised separately still had many similarities suggesting that there was a genetic influence at work now the last theme that informs developmental psychology is continuous vers discontinuous development this theme explores how smooth or gradual the developmental process is continuous refers to development that is gradual and smooth while discontinuous refers to development that occurs in distinct stages or steps later in this unit we'll look at voty social cultural Theory which focuses on continuous development stating that development is influenced by social interactions and culture occurring over time we will also look at PJ's cognitive development theory and Eric Ericson's stages of development which are examples of discontinuous development each highlighting distinct stages that an individual will go through during their life now I do want to point out that our understanding of human development is still evolving for instance Rec recently researchers have gone back to examine the idea that motor development happens in discontinuous stages studies such as the cross-cultural research on motor development which is an example of a cross-sectional study found that culture most likely plays a larger Factor on infant motor development than previously believed this has led to the belief that certain Milestones like sitting crawling or walking may happen continuously with cultural factors influencing the development remember cross-sectional research involves studying different groups of people at different ages all at the same time cross-sectional research allows researchers to gather data quickly comparing various groups all at once this not only allows for quicker results but is also less expensive compared to longitudinal studies however cross-sectional research can't show any relationship between variables and it also can't show change over time think of it as the fast food of research quick relatively cheap and it gets the job done but don't expect it to tell you how you're going to feel in about 20 years cross-sectional research also has a chance of being impacted by the cohort effect remember a cohort is a group of individuals who share common characteristics generally when we are talking about cohorts and data we are talking about people in the same age range now the cohort effect is when there is differences among a group of people that are caused by circumstances that are unique to their generation rather than by their age so essentially the impact of cultural factors on the individuals in the cohort we can see that the cohort effect could impact the results of a study since results may vary due to cultural factors and not due to the differences between the age groups now to make sure all of this is making sense I made a practice quiz that reviews all the different themes and research methods plus I also included explanations for each quiz question explaining why each answer is either right or wrong so you can truly understand the content you can find the practice quiz inside my ultimate review packet by clicking the link in the description down below so at the end of the day we can see that these themes often help guide research shape different perspectives help interpret findings and help inform the application of different findings all right that's all the time we have for today don't forget to check out the ultimate review packet for more help in your studies and if you're looking for an online study group consider joining for free the Mr sin Discord server as always I'm Mr sin thank you so much for watching and I'll see you next time online