COMmon assumptions of cognitivE Training (COMET) Project: A trial evaluating the assumption that working memory training should comprise variations of the training activities in children aged 7-11 years

The COMET project evaluates common assumptions of working memory training interventions using an experimental working memory training intervention designed and developed specifically for the project. The intervention and its delivery were co-designed with developmental cognitive scientists with input from teachers, parents and primary school children. This approach ensures the design of the intervention is scientifically rigorous, including common design features of current cognitive training interventions considered effective at improving children's working memory, and also ensures both the intervention and its delivery are acceptable and feasible to teachers, caregivers and primary school children so that it is engaging and can be used in the classroom. In this trial the working memory training intervention comprises two experimental working memory activities that are gamified and involve the temporary storage and manipulation of verbally presented target information: a backward span activity and a following instructions activity. For each activity, the difficulty will be adapted to the child's performance, with all children starting the first session at the same level and then the difficulty of a trial will be based on the child's previous performance. The child completes both activities in each session. Motivating features of the intervention include the story line across the training sessions, and collecting experience points while completing the activities which can be used at the end of each session to build in the worlds. For each participating child, the data for each training session will be uploaded and will enable researchers to monitor adherence to the intervention. The intervention schedule will involve completing a total of 10 sessions of 20 minutes duration, performed each school day for 2 consecutive weeks. It will be delivered by the teacher in class. Each child will individually perform the intervention on an iPad with headphones provided by the researchers. All teachers will be provided one handout summarising key information about the intervention and its delivery, including the storyline, schedule, how to log in, instructions such as students watch the information video on their iPad at the start of session 1, and contact details for any questions. In this trial the working memory training intervention has three arms, which differ in the number of variations of each training activity: Arm 1 - Two activities, where the trainee practices on one backward span activity and one following instructions activity within each training sessions. Arm 2 - Four activities, where the trainee practices on two variations of the backward span activity and two variations of following instructions activity within each training session. Arm 3 - Six activities, where the trainee practices on three variations of the backward span activity and three variations of the following instructions activity within each training session. Participants will be randomly allocated to one of the three arms based on a randomisation scheme that will be generated in advance and set up in REDCap. To randomise a participant, an authorised research team member will login to REDCap, enter eligibility and stratification data on the participant, and will receive the group allocation. User access restrictions will prevent anyone outside of the trial statistician from setting up or viewing the allocation sequence prior to a participant being randomised.