Visiting the CoCoSys lab was an easy decision (pardon the pun). In this post, I’d like to share my experience at the lab and offer some insight for others considering a similar research visit or collaboration.
I’m a third-year PhD student in the O’Connell Lab at Trinity College Dublin, where my research focuses on understanding variability in human decision-making using psychophysical methods, EEG, and computational modelling. Much of the work in decision neuroscience investigates how behaviour changes in response to experimental manipulations. While this is undoubtedly valuable, it can often overlook an equally important dimension: how endogenous fluctuations — such as spontaneous shifts in attention, arousal, or latent cognitive states — shape behaviour over time.
These internal dynamics can give rise to meaningful variability that traditional models might overlook. A promising framework for uncovering and characterising these latent states is Hidden Markov Modelling (HMM). My visit to the CoCoSys lab was designed to gain hands-on experience with these models, to apply them to human behavioural data, and to build a collaboration that would continue beyond my time in the lab.
I first met Dr. Anne Urai at a conference in the summer of 2022, where it became clear we shared a strong interest in understanding the mechanisms underlying decision-making variability — Anne’s lab focusing primarily on large-scale mouse data from the International Brain Laboratory (IBL), and my own work centring on human datasets. What stood out in our conversation was a shared desire to move beyond simplistic interpretations of behavioural variance and to develop richer, state-based accounts of decision-making.
Beyond our research alignment, I was also drawn to Anne’s visible advocacy in areas such as climate action, open science, and equity in academia. These values are clearly embedded in the lab’s culture and added to my motivation to establish a collaboration.
Reaching out to initiate a collaboration can feel daunting, but from the outset, I was met with nothing but warmth and encouragement. Anne was incredibly generous with her time and guidance throughout the process of organising the visit. In the months leading up to my arrival, we held several online meetings to co-develop a project that aligned with both our research goals and would make the best use of the two weeks I would spend in Leiden.
During my stay, I learned to implement HMMs on human data and gained valuable insight into the practical challenges and nuances of modelling latent state dynamics. The visit also gave me the opportunity to present my research to the wider cognitive psychology department — a rewarding experience that pushed me out of my comfort zone and led to engaging discussions. I worked closely with Dr Philippa Johnson, a postdoc in the lab, who provided outstanding support and feedback throughout the project. Regular check-ins with Anne helped shape the direction of the work and laid the foundation for continued collaboration.
The lab environment itself was incredibly welcoming. From the outset, I felt like part of the team. There’s a strong sense of community in the department, with cross-lab collaboration encouraged through joint meetings and shared lunches — something that made the experience both intellectually stimulating and personally enjoyable.
I’m excited to continue our collaborate on remotely. Watch this space for (hopefully!) exciting results on how latent states differ with age across species.
I’m deeply grateful to Anne for hosting me and providing unwavering guidance, and to Philippa for her patience, support, and generosity with her time.
If you’re considering a visit to the CoCoSys lab or thinking about initiating a collaboration, I couldn’t recommend it more highly. Feel free to reach out if you’d like to hear more about my experience — I’m always happy to chat (jduffy9@tcd.ie)!
CoCoSys lab 