In spring 2023, a group of SCONe researchers decided on a common research project that soon focused on reviewing the literature, and potentially doing a meta-analysis, on the strength of alpha lateralisation. We picked this effect because it is well-documented and generally accepted. It should therefore make for a proving ground for our large-scale literature survey.
Our motivations were to check how effect sizes were usually reported, borne out of a move away from only reporting the existence of an effect towards how strong it is. It seems generally more interesting to know that cued shifts of attention (or other cognitive experimental manipulations) explain x% of variability in, rather than just knowing that they do (not) affect brain activity. Ultimately, we hope to provide a benchmark for effect sizes in cognitive neuroscience to compare novel or less established findings to. Moreover, we aim to assess how effect sizes for alpha lateralisation vary across different types of designs, modalities, or design factors (if our final set of papers includes enough relevant papers).
Screeners at work
After laying the groundwork, and researching approaches, we finally settled on using cutting-edge systematic review tools. For the first stage of title and abstract screening, following a literature search that produced ~4500 results, we used an AI tool, ASReview, that helped massively by reducing the amount of work by about 90+% (only x abstracts were scanned by two screeners). The resulting 300+ eligible studies then underwent a full-text screening involving 10 screeners, and excluding studies using a fixed set of criteria. This and the following stage made/make use of Covidence, an online tool specifically designed to support screening efforts for systematic reviews.
We met in Dundee in early March 2024 for a titration screening and finalising the criteria for all screeners. With the screening nearing completion, we are currently finalising the data extraction process that will be followed by a data analysis stage to determine effect sizes.
Getting some fresh air at Loch Brandy, Glen Clova
Our progress has been hugely engaging and the learning experiences, discussions and meetings have been invaluable opportunities for exchange. The effect size project steering committee, including Lui Ka Yan (Troby), Laura-Isabelle Klatt and Christian Keitel, say huge thanks to everyone involved in the project so far: Karin Bakardjian, Chris Benwell, Emily K Cunningham, Anne Keitel, Martina Kopcanova, Manuela Ruzzoli, Linda Drijvers, Malte Wöstmann, Benedikt Zoefel, Søren K Andersen, Marlene Rösner, Philipp Ruhnau.
Please get in touch for questions and suggestions, and stay tuned for updates!