Research | Code | Communicating Science

Sharing research, code repositories and blog posts

About me

Hi! I’m Ceyda Sayalı. I’m a postdoc at Johns Hopkins University, Center for Psychedelic and Consciousness Research. My primary interest is in understanding the neurocognitive mechanisms underlying the therapeutic effects of psychedelic drugs. I use functional Magnetic Resonance Imaging (fMRI), Transcranial Magnetic Stimulation (TMS), electroencephalogram (EEG) and physiological measures (such as pupillometry) on healthy and patient populations (such as Parkinson’s Disease patients and patients with major depressive disorder) with and without pharmacological manipulations. In addition to my academic work, I aim to learn and participate in conversations about fostering diversity in academia, particularly in the field of biomedical sciences. On this webpage, you can find my publications, code repositories and posts about my research and professional experiences.

My research experience:

Undergraduate & lab manager at Koc University (2006-2013)

As an undergraduate in Istanbul, Turkey, I studied Psychology and Philosophy. My interests in cognitive neuroscience started through my extracurricular collaboration with work with Prof. Resit Canbeyli, from Bogazici University. Through this collaboration, I conducted experiments on Wistar rats that examined the relation between behavioral despair and learning, in an effort to define the behavioral effects of depression. My experience with this research filled my curiosity about the neurocognitive mechanisms underlying depression in humans. Therefore, I aimed to develop my skills in cognitive psychology and apply for a PhD program in cognitive neuroscience in the USA. Upon the receipt of my baccalaureate degree, I accepted a job offer from Koc University, as Dr. Fuat Balcı and Dr. Ilke Oztekin’s first lab manager for a nascent computational psychology lab. There, I gained training in Matlab programming and started comfortably coding new experiments and analyzing data, while simultaneously overseeing the challenges of opening a new lab. I collaborated with undergraduate and graduate students in the lab, over the course of two years. I was responsible for conducting and overseeing numerous research projects for both Dr. Oztekin on working memory and Dr. Balcı on time perception. During this time, I independently tested the dopamine based internal clock hypothesis in interval timing, and the role of feedback on working memory.

Ph.D. student employee at Brown University (2013-2018)

At Brown, I primarily worked with Dr. David Badre. I aimed to receive a deeper cognitive understanding of what might lead to apathy, a distinguishing symptom of depression. I realized that depressed patients place less subjective value on the same outcomes that healthy people find appealing. This leads to a lack of motivation to pursue these devalued outcomes (e.g. apathy). However, a common mechanism that affects both healthy and depressed individuals was demand avoidance: everyday decisions, like deciding to diligently review your analysis versus skimming it over before manuscript submission, are influenced by estimates of the cost of cognitive effort. Therefore, in order to understand the mechanisms underlying the costs/benefits associated with cognitive control, I developed a novel experimental demand avoidance paradigm and tested the neural mechanisms using fMRI underlying the learning of effort costs, the decision to avoid effort as well as a behavioral paradigm that delineated the source of cognitive effort costs

Postdoc at Donders Center for Cognitive Neuroimaging (2018-2021)

My findings during my PhD at Brown University informed me that ‘cost of cognitive control’ hypothesis of cognitive effort cannot fully account for all effort decisions and that individual differences underlie the evaluation of the same effort costs. To reconcile these findings, I designed a novel paradigm in my first postdoc, where I primarily worked with Prof. Roshan Cools (at Donders Institute, the Netherlands).  In my research with her, I adopted both objective and subjective measures to explain the cost/value associated with cognitive effort as a function of individual differences in trait-level affective states. I showed that what is underlying the link between task engagement and effortful tasks might be dynamic range that these tasks yield for minimization of performance accuracy prediction errors based on individual’s own capacity for a task, or in other words, the individual’s potential for performance improvement at that task. Moreover, pupil size, as a proxy for noradrenergic arousal tracked these performance improvements, boosting task-engagement.

Moreover, during my postdoc at Donders Institute, I aimed at receiving pharmacological intervention training. To do so, I collaborated with Dr. Rick Helmich who is both a researcher and a neurologist at the Parkinson Centre Nijmegen, works on motor and cognitive problems in Parkinson’s Disease (PD) patients, using neuroimaging and physiological measures. In my collaboration with him, I assessed cognitive deficits in PD patients as a function of dopaminergic drug manipulation using fMRI and a double-blind, randomized, within-subject design. 

Postdoc at Johns Hopkins University (2021-present)

At the Center for Psychedelics and Consciousness Research, I primarily work with Dr. Fred Barrett. Currently I’m working on multiple projects. In one, using fMRI, we are investigating the post-dose neurocognitive effects of psilocybin-assisted therapy on patients with concurrent major depressive disorder and alcohol use disorder in a randomized double-blind placebo-controlled within-subject design clinical trial. In another, using EEG, we test the acute neurocognitive effects of psilocybin in healthy volunteers. We also ask methodological questions regarding the reproducibility of TMS evoked EEG signals.

Code on Github

On this page, you can find codes written mostly in Matlab and some in JavaScript, html and css. Some of my scripts are optimized for fMRI, some are optimized for EEG, some for TMS and some for pupillometry. Check out my repos and feel free to ask me questions!

Code repositories:

I publicly share my experimental scripts on Github. You can see a summary of my contributions here:

Parametric Effort Selection Task

This is a parametric effort selection task I developed during my Ph.D. at Brown University. This study is optimized for fMRI testing. You can run this game on Matlab with Psychtoolbox.

Optimal Effort task

This is a cognitive effort evaluation task I developed during my first postdoc at Donders Institute. This task is optimized for concurrent pupillometry use. You can run this task on Matlab with Psychtoolbox.

Optimal Effort task for online testing

The above Optimal Effort task is translated into Javascript, html and css, hosted by You can also run this on your browser via Virtual Studio Code

Probabilistic Reward Learning

I also translate established experimental paradigms and post them on my Github. Probabilistic Reward Learning task is one of them! You can run this task using Matlab and Psychtoobox.

TMS noise click

Concurrent TMS-EEG recording can be tricky. One way to reduce auditory artifacts caused by TMS is to use noise masking. You can run this code using Matlab.

Alternative Uses Task

This is a creativity game adapted for EEG recording. You need Matlab, Psychtoolbox and a Biosemi device for this one.


  • Are smart drugs the smart choice for everyone?
  • Why put in the effort if there is nothing to learn?
  • The costs and benefits of psychedelics
    Psychedelic art, a movement that started in the 1960s, was inspired by the insights derived during the use of psychoactive substances that are known as psychedelics. From the unique riffs of Janis Joplin’s Summertime to the designs of Wes Wilson’s posters, psychedelic art overwhelmed the audience with kaleidoscopic images and fractal sounds. Albert Hoffman,… Read more: The costs and benefits of psychedelics
  • When effort is fun
    All throughout my Ph.D., I tried to understand what makes us avoid cognitive effort. The concept of ‘effort avoidance’ just felt so intuitive, specifically when I was struggling with the requirements of a Ph.D. program. Cognitive effort must have held an intrinsic cost! On a typical day (and not just during a Ph.D. program!!),… Read more: When effort is fun
  • Around the world in a science haze
    Functional Magnetic Resonance Imaging (fMRI) revolutionized cognitive neuroscience and how we understand the mind-body relationship in human research. With the use of fMRI, we can localize brain functions with precision and test theoretical assumptions about the nature of cognitive processes. fMRIs are also million dollar machines that cost ~$500 per scan. That means allocating… Read more: Around the world in a science haze

Social Media

Contact Me

Email: zsayali1[at]