I am running a study looking at pre-pulse inhibition in a clinical sample.  I’m recording eye blink response with EMG as my measure of startle.  I was wondering if anyone has experience running PPI studies and/or using eye blink as a measure of startle response that would be willing to answer some questions? For instance, what do you do with data when there is no response to a startle probe (this seems to happen at random)?  How do you ensure participants are attending to the task without introducing a new variable (such as a visual cue)?  Any advice would be very much appreciated! Thanks.