A Single-case Design to Investigate a Compensatory Strategy Game Supporting Goal Management Training

Change on the Visual Analogue Scale (VAS) from phase A to phase B to follow-up

Subjective experience of strategy use in daily life and during the performance of instrumental activities of daily living (IADL).

Time frame: The VAS will be assessed repeatedly, two times a week, for the duration of phase A (3 to 5 weeks), phase B (3 weeks) and follow-up (3 weeks)

Change in performance on treatment goals as measured with the Goal Attainment Scale (GAS)

GAS is a mathematical technique for quantifying the achievement of goals set, used in rehabilitation. GAS is described as a method of scoring the extent to which patient's individual goals are achieved in the course of intervention. In effect, each patient has a own outcome measure, but this is scored in a standardized way as to allow statistical analysis. The achievement of each goal (IADL-task) can be measured on a 5-point scale ranging from -2 to +2. Outcomes can be quantified in a single aggregated goal attainment score. This method gives a numerical T-score which is normally distributed about a mean of 50 (if the goals are achieved precisely) with a standard deviation of around this mean of 10 (if the goals are overachieved or underachieved).

Time frame: pre-intervention, immediately following intervention and at three weeks follow-up

Change in performance on two trained IADL task (treatment goals)

Performance on two treatment goals is measured with a standardised scale which is similar to the one used by Bertens et al. (2015) and Dechamps et al. (2011). The tasks will be divided into multiple steps using the GMT method. Each task step will be assessed following a 3-point scale (ranging from 2=competent to 0=deficit). Total scores per task will be adjusted to a 100-point scale using the following formula: performance = (total score / (number of steps × 2)) × 100. Thus, a performance of 100% indicating perfect IADL task performance.

Time frame: pre-intervention, immediately following intervention and at three weeks follow-up

Change in everyday difficulties in activities/participation as measured on the Daily Living Questionnaire (DLQ-R-NL)

The Dutch version of the Daily Living Questionnaire measures how much mental or cognitive difficulty the participant generally has by performing daily activities.

Time frame: pre-intervention, immediately following intervention and at three weeks follow-up

Change in strategy use during the performance of trained and untrained IADL tasks

A self-designed questionnaire to examine self-reported strategy use will also be administered after the performance of the trained and untrained IADL tasks, based on the strategy questionnaire used by Frankenmolen, Fasotti, Kessels \& Oosterman (2018), in order to measure strategy use in a traditional memory task. First, participants are openly asked which strategies they use during the performance of an IADL task. Subsequently, they are given a list with possible strategy components of GMT that one could use to perform a task and are asked to place a check mark next to each strategy that they had used.

Time frame: pre-intervention, immediately following intervention and at three weeks follow-up

Change in subjective experience of strategy use in daily life

GMT strategy use is assessed through an adjustment of the Strategy Use Inventory; SUI (Koning-Haanstra, Berg, \& Deelman, 1990). Participants have to indicate how often they use a certain strategy in daily life situations using a 5-point rating scale ranging from 1 (never) to 5 (often). Average item scores are calculated.

Time frame: pre-intervention, immediately following intervention and at three weeks follow-up