FIGURE 1.

Illustrates three tasks that parametrically manipulate working memory (WM) updating (through rule-order) and WM maintenance (through the number of alternatives maintained in WM for action). Across all tasks, performance costs on the 1 versus 2 blocks measure the cost of updating higher order rules into working memory for action as well as increasing WM maintenance, whereas performance on the 2 versus 4 blocks isolates the cost of WM maintenance. The Response task R1 block is a zero-order rule. A single response is correct for any stimulus. Correct response on R2 and R4 blocks requires updating of first-order rules into WM, where the color of the box indicates the correct response. The R4 block maintains the same first-order rule structure as R2, but adds additional alternatives for WM maintenance. The Feature and Dimension tasks follow the same logic. The Feature task F1 is a first-order rule block, while F2 and F4 are second-order blocks. Participants are instructed to determine whether the arrow is pointing in the right direction given the box color. Among the second-order F2 and F4 blocks, only the number of competing alternatives for WM maintenance (from 2 to 4) is increased. The Dimension Task D1 block is a second-order block, whereas D2 and D4 are third-order rule blocks. Participants are instructed to use the box color to then select a dimension (shape, orientation) to then match to an arrow direction. D2 and D4 are both third-order rule blocks, but D4 increases only the number of competing alternatives maintained in WM for action