1. Flanker Task In the Standard Flanker Task, the participant should focus on the CENTRAL stimulus and ignore the flanking stimuli on either side. For example, in this frame, the middle fish is pointing Left, so the correct response is to press the Left button. Press Return or Click Slide

2. Reverse Flanker attend to the flankers We have introduced a Reverse Flanker condition, where paarticipants are to attend to the OUTSIDE stimuli and ignore the central stimulus. For example, in this frame, the outside fish are pointing Right, so the correct response is to press the Right button. Press Return or Click Slide

3. Flanker Effect by Stimulus Type 300 The Flanker Effect has been replicated many times, but is quite sensitive to stimulus parameters. For instance, here you can see that there is a Flanker Effect for both standard (Inside) Flanker and for reverse (Outside) Flanker, but the effect essentially disappears when the stimuli are large. 250 200 msec 150 100 50 0 Large Inside Small Outside Large Outside Small Inside Block 1

4. Flanker Effect for Single-Task Block vs. Mixed Block Non-Switching Trials Only 300 250 200 msec 150 100 50 0 Large Inside Large Inside Small Inside Small Outside Large Outside Small Outside Large Outside Small Inside Block 1 Block 3 (Mixed) Regardless of stimulus size, or whether a trial has an Inside or Outside target, the Flanker Effect is far larger (6-10 times larger) when standard and reverse Flanker trials are intermixed

5. Flanker Effect for Single-Task Block vs. Mixed Block Non-Switching Trials Only 300 Note that this is the Flanker Effect, not any Switch Cost Effect, and ONLY non-switch trials even from the mixed block are included here. 250 200 msec 150 100 50 0 Large Inside Large Inside Small Inside Small Outside Large Outside Small Outside Large Outside Small Inside Block 1 Block 3 (Mixed) Also, when standard and reverse Flanker trials are intermixed, the Flanker Effect is no longer sensitive to stimulus parameters such as stimulus size.

6. Flanker Effect by Block (Standard vs. Mixed) INSIDENon-Switching 300 250 200 msec 150 100 50 0 Block 1 Block 2 Block 3 (Mixed) Block 4 Block 5 This dramatic increase in Flanker Effect size is NOTdue to practice effects. Note that the Flanker Effect in the Mixed Block is larger than both the blocks before it AND after it.

7. Dramatically Larger Flanker Effects Sarah Munro, Cecil Chau, Karine Gazarian & Adele Diamond Presented at the Cognitive Neuroscience Society Annual Meeting, San Francisco, CA, April 9, 2006.

8. Diamond, A., Barnett, W.S., Thomas, J., & Munro, S. (2007). Preschool program improves cognitive control, Science, 318, 387-388. The standard and reverse Flanker conditions were used with 5-year-olds as part of a study to evaluate the efficacy of a preschool intervention that targets Executive Functions…

9. District Curriculum 90 Tools of the Mind Curriculum (TOM targets EFs) 80 Children in the Tools of the Mind preschool program performed significantly better than children in the District Curriculum on the standard Flanker condition, though the difference was not large. In the Reverse Flanker condition (which was always presented AFTER the standard condition), the difference was both significant AND large. 70 Correct Responses (%) 60 50 40 30 Flanker Rev. Flanker