It is not that participants forget the rules.   It is not that participants forget the rules. Indeed, children often call out the correct higher-order rule on trials in the mixed condition (e.g., “same,” “opposite,” “opposite,” “same”) even as they are making errors. The problem seems to be in quickly translating the rule into the correct response when switching back & forth. 2 2

In the Incongruent condition, besides needing to hold one abstract rule in mind (“press on the side opposite the dot”), you need to inhibit the natural tendency to respond on the same side as the stimulus. In the Mixed condition, working memory is needed to hold TWO abstract rules in mind and mentally translate same/opposite into L or R, cognitive flexibility is needed to switch between rules, and inhibition is needed on incongruent trials and switch trials.

re-setting one’s attentional focus, re-orienting one’s mindset --   It is SWITCHING – re-setting one’s attentional focus, re-orienting one’s mindset -- that is most difficult & when DL-PFC is most critically required.

Increased Activation of Dorsolateral PFC (Area 46/9) Dots-Mixed minus Dots-Congruent Talairach: (34, 45,25) (-40, 45,28)

JK slice 13 Dots-Mixed minus Dots-Congruent Slice No. 13 10-year-olds

Dots Conditions: Accuracy Congruent Incongruent Mixed 100 90 80 Percent Correct 70 60 50 4 5 6 6 7 8 9 10 11 13 26 Stimuli presented for 2500 ms Stimuli presented for 750 ms Age in Years Davidson et al. (2006). Neuropsychologia, 44, 2037 - 2078

Adults have little difficulty exercising inhibition in steady-state in single-task blocks, but children of all ages demonstrated a cost in doing so, albeit a much lesser cost than intermittently exercising that inhibition.

Increasing demands on inhibition are more difficult for children (ages 4-9 years) than increasing demands on how much information they must hold in mind (2 to 6 items). The opposite is true for young adults: increasing memory load is disproportionately more difficult for adults than increasing inhibitory demands. Adults may not appreciate how inordinately difficult inhibition is for young children because it is less taxing for us.

published in Neuropsychologia Development from 4-13 Years of Cognitive Control and Executive Functions: Evidence from Manipulations of Memory Load, Inhibition, and Task Switching Matthew Davidson Loren Cruess Anderson Dima Amso & Adele Diamond published in Neuropsychologia vol 44, pages 2037 - 2078