Post hoc/simple effects for 2-way repeated measures ANOVA

Hi there,

I am quite confused about how I would go about locating an effect in a 2-way repeated measures ANOVA. I have 10 participants and for each I have there response times when they carried out a target detection task (where they had to say whether or not a target was present) for when the target was present vs absent, with either 3,6,9 or 12 distractors present. I know you can't use post-hoc tests such as Tukey for this design, so what would you normally do?

Many thanks