My task involves blocks of a flanker task. Each block runs through a sequence of two types of trials. I want participants who have >90% correct and <75% correct at the end of the block on one type of trial only (flankertrial) to see a message telling them to go faster or go slower (and participants who have between 75 and 90% percent correct on those trials to see nothing).

I tried adding this branch to my <block>: 
/ branch = [if (trial.flankertrial.percentcorrect < 90) trial.speedfeedback]
/ branch = [if (trial.flankertrial.percentcorrect > 75) trial.accuracyfeedback]

But it came up with an error: the element 'speedfeedback' in branch expression 'speedfeedback' is the wrong element type. I'm assuming this means I can't branch to a trial if I use it in the block element. 

My next attempt was to add a branch to my <trial flankertrial>: 
/ branch [if (trial.flankertrial.count < 80) notrial]
/ branch = [if (trial.flankertrial.count == 80 && trial.flankertrial.percentcorrect < 90) trial.speedfeedback]
/ branch = [if (trial.flankertrial.count == 80 && trial.flankertrial.percentcorrect > 75) trial.accuracyfeedback]

Error: expression contains an unknown element or property name. 

I'm thinking that the trial.flankertrial.count won't work because the count would always be 1 within the trial, which is why my first instinct was to add something to the block level. At this point I'm not sure how I can specify that participants should see a simple text message after the block depending on their percent correct on one of the two trial types. Any ideas?