Online testing in developmental science: A guide to design and implementation

At present, most developmental psychology experiments use participants from a mere subsection of the world's population. Moreover, like other fields of psychology, many studies in developmental psychology suffer from low statistical power due to small samples and limited observations. Online testing holds promise as a way to achieve more representative and robust, better powered experiments. As participants do not have to visit in person, it is easier to access populations living further away from a developmental lab, enabling testing of more diverse populations (e.g., urban vs rural areas, various different nationalities or geographies), both within and beyond the researcher's home country. Furthermore, due to the codified nature of browser-based online testing, it is possible for multiple labs to carry out the exact same study, allowing for better replications. Because of these advantages, developmental researchers have started to move experiments online so that caregivers and their children can participate from their home environments. However, the transition from traditional lab testing to remote online testing brings many challenges. Laboratory studies of infant and child development are typically conducted under highly standardized conditions to control factors, such as distractors, distance to the screen, movement, and lighting, and often rely on specialized equipment for measuring behavior. In this chapter, we provide a guide for researchers considering online testing of a developmental population. The different sections comprise an overview of the decision-making processes and the state-of-the-art advances associated with, as well as tangible recommendations for, online data collection.