Switching between tasks

For my masterthesis I'm doing a study into people who play online chess and their abilities to switch between tasks. Therefore, I will ask you in this study to do a short, but difficult task where your response time will be measured. Please try to do this task as quickly as possible, but also as correctly as possible. Furthermore you will be asked to give some data about your demographics and online chess activities.

Please note that you need to be at least 18 years old to participate and can't do the study on mobile or tablet.

The link to the study: https://www.psytoolkit.org/c/3.4.4/survey?s=y2xf2

Thank you in advance for your participation!

For this task psytoolkit.org was used, references:
Stoet, G. (2010). PsyToolkit: A software package for programming psychological experiments using Linux. Behavior Research Methods, 42(4), 1096–1104. https://doi.org/10.3758/brm.42.4.1096
Stoet, G. (2017). PsyToolkit: A novel web-based method for running online questionnaires and reaction- time experiments. Teaching of Psychology, 44(1), 24–31. https://doi.org/10.1177/0098628316677643