Table 3.

WMDEC predictions regarding task switching performance as tested in Studies 1 and 2 and a motivation why the model supports these predictions.

PREDICTION	WHATa	WMDEC EXPLANATION
Study 1: Task preparation and switch cost (SC)
Task preparation	P+ > P–	Cue processing and goal activation may complete before the task stimulus (target) is presented
Task switch cost	Ptr > Pts	On switch trials but not on repetition trials, a new task set must be activated and configured in EM
SC reduction	Ct+ > Ct–	Preparation effect is smaller on repetition trials because less preparation is required
Residual SC	Ct > 0 (always)	Task set activation and configuration can only complete after the target is presented
Study 2: Task and dimension switching
Dimension SC	Pdr > Pds	When the task repeats, a dimension switch requires changes to the active task set
Task/dimension SC	Ct > Cd	A task switch requires a completely new task set including a dimension configuration, whereas a dimension switch requires only a change to a task set parameter when the task remains the same
Alternative	Ct = Cd = Ct+d	If it is assumed that every combination of task and dimension requires its own task set, any change (task, dimension or both) requires activation of of a new task set

^a Predictions are formulated in terms of performance (P) as a function of preparation time (+ for longer, – for shorter) or transition (ts for task switch, tr for task repetition), where higer performance corresponds to faster RT and fewer errors. Some predictions are formulated as a performance difference score, namely switch cost (C_t = P_ts – P_tr for task switch cost, C_d = P_ds – P_dr for dimension switch cost).