The PEBL Flanker Task 
An implemenation of the "Eriksen Flanker Task",   see Eriksen, C. W., & Schultz, D. W. (1979).  Method modeled roughly after one described by Stins et al, 2007.
However, it includes a 'neutral' as well as congruent/incongruent.

See also PEBL's 'ANT' task, a complexified version
of this task.
