PEBL's Symbol-Counter Task.  After Gehring's implementation of Garavan's task. Keep track of two counts represented by four symbols.

Data are saved to symbolcount-X.txt and symbolcount-report.txt in the symbolcounter/ directory.
To cite:  Mueller, S. T. (2011). The PEBL Symbol Counter Task.  Computer software retrieved from http://pebl.sf.net/battery.html
