Final answer:
The research design for a study on communication in young children with Fragile X Syndrome is likely a case study, which is well-suited for in-depth investigation of rare phenomena, collecting qualitative data to understand developmental psychology and genetic disorder effects.
Step-by-step explanation:
The type of research design suitable for a study titled "Communication in Young Children With Fragile X Syndrome" aiming to provide descriptive information about communication would likely be a case study. Case studies are in-depth investigations of a single person, group, event, or community. Typically, data are gathered from a variety of sources and by using several different methods (e.g., observations & interviews). Specifically, in psychology and child development, case studies can provide valuable insights into developmental milestones and the impact of specific conditions, like Fragile X Syndrome, on a child's communication abilities.
Such a design is appropriate when investigators are examining a rare phenomenon, which is certainly the case with this genetic condition. The research design will focus on the qualitative aspects of communication, collecting data through direct observations, interviews with caregivers, speech analysis, and possibly other forms of data like medical records. The study would highlight the unique aspects of communication in children with this syndrome and contribute to the understanding of developmental psychology as well as the effects of genetic disorders on child development.