Alexandra Decker

Assistant Professor

Alexandra (Lexi) Decker is the Principal Investigator of the How We Learn Lab. Before joining WashU, she was a postdoctoral fellow in the Department of Brain and Cognitive Sciences at the Massachusetts Institute of Technology, working with John Gabrieli. She completed her PhD in Psychology at the University of Toronto, where she trained with Amy Finn and Katherine Duncan, and her BA in Psychology at McGill University.

Lexi is a developmental cognitive neuroscientist whose work examines how we learn and form memories across development, and why learning can look so different across people. Her lab uses behavioral tasks, eye-tracking, pupillometry, and neuroimaging, alongside computational modeling and statistics, to track learning and memory on a moment-to-moment basis. She is particularly interested in how factors like attention, arousal, reward, and conflict shape what we learn, as well as how brain plasticity and environmental adversity or enrichment influence how children’s brains and cognitive systems develop.

Outside the lab, Lexi enjoys running, going for long walks in Forest Park (often with impromptu visits to see the polar bears at the zoo), drinking coffee, and thinking about philosophy. She especially enjoys spending time with her husband. She is excited to collaborate with colleagues and students across Washington University in St. Louis.

Nick Bashaw

Assistant to Chair

Nick Bashaw joined P&BS in April 2026 as the Administrative Assistant. He will fully transition into the role in June as he takes over responsibilities from Cheri. He first came to WashU in April 2025 as the Administrative Coordinator for the Department of Mathematics, where he supported the chair, managed key administrative processes, and served as the primary point of contact for faculty, students and visitors. Before coming to WashU, Nick worked as a retail manager and certified optician at Warby Parker. Since he has been at WashU he has come to appreciate the sense of community here that he was missing in his previous positions. He is especially excited about joining P&BS because of the scale of work going on and the strong community atmosphere.

Outside of work, Nick is an accomplished and active musician, performing around 70 times each year. His recent highlights include performing in Les Misérables at The Muny in 2024 and singing at the Sydney Opera House in 2019—experiences that reflect both his talent and passion for performance.

Whether coordinating departmental operations or performing on stage, Nick brings energy, dedication, and a collaborative spirit to P&BS. We’re excited to have him on the team and look forward to all he will contribute.

William Chopik

Associate Professor

Dr. Chopik studies the individual and relational characteristics associated with health, cognition, and well-being across the lifespan. His work relies on methods that quantify social influence, longitudinal change and its antecedents, and the causal effects of psychological characteristics on important life outcomes, particularly in late life. Dr. Chopik will be joining the department in Fall 2026.

Juston Osborne

Assistant Professor

Dr. Osborne is currently a Postdoctoral Research Scholar working with Dr. Deanna Barch. He completed his Ph.D. in Clinical Psychology at Northwestern University. His research is focused on identifying the neural mechanisms and processes that underlie the risk for developing psychotic disorders. A major area of his research examines how motor system abnormalities, particularly abnormalities in the cerebellum and its relays, contribute to the progression and onset of psychosis symptoms. Dr. Osborne will be joining the department in Fall 2026.

Ruowen Pei

Grants Specialist

After graduating from Washington University with a degree in Chemistry, Ruowen built a diverse foundation across several roles, including faculty assistant and lab prep specialist for the Chemistry department, and grants administration in Earth and Planetary Sciences and now in P&BS. Each position offered a unique work style—from personal, student-focused interactions to structured lab routines and the fast-paced, ever-changing world of grants. This variety has been one of the most exciting aspects of Ruowen’s journey at WashU.

Since joining P&BS, Ruowen has especially valued the close-knit staff culture, strengthened by frequent communication and department lunches. The role has also provided the opportunity to work more directly with faculty, their labs, and the business office, offering a deeper understanding of the research environment.

Bringing a detail-oriented mindset—what Ruowen likes to call a “nitpicky” eye— he helps to ensure accuracy and catch important details that might otherwise be overlooked.

Outside of work, Ruowen likes to enjoy life’s simple pleasures, from walks in the park to documentaries about how things work or nature, he also really enjoys a well prepared dish when eating out. Ruowen loves traveling, exploring new cultures, hiking, and trying new cuisines.