Need help with scoring a stroop task - no neutral condition

As part of this study I have multiple presentations of a stroop task (stroop-reverse-stroop) separated by 3 minutes and another task in between. I am interested in increase in interference between 1st and last Stroop. I am trying to find a “standard” method of computing a single score from a stroop task so that I can compare those scores (have reaction time and hit/miss on 24 trials each presentation). Unfortunately I have no neutral (black-only) condition, which seems necessary in what I’ve been able to find so far. I KNOW others use this without a neutral condition so I know someone has to know what to do with this data. Any suggestions would be highly appreciated.