question regarding viz.getpostion written into text file

[Erikvdb]

I'm not entirely sure what you mean, and it's hard to read the code without indentations (please use the CODE tags next time), but could it be that you are not stopping the timer and closing the datafile after each trial? If that's the case, the timer for the first trial just keeps on writing data during the second and third trial; the timer for the second trial will keep on writing during the third, and only the last one will write just the data of the last trial.