# Evaluating expressions in trigger\_watch variables **URL:** \ **Category:** Support\ **Created:** [April 1, 2016, 2:19pm UTC](https://mworks.discourse.group/t/evaluating-expressions-in-trigger-watch-variables/454 "2016-04-01T14:19:29Z")\ **Posts on this page:** 3\ **Page:** 1
**Author:** ![cstawarz](https://yyz1.discourse-cdn.com/flex031/user_avatar/mworks.discourse.group/cstawarz/32/3_2.png) [@cstawarz](https://mworks.discourse.group/u/cstawarz)\ **Post date:** [April 1, 2016, 2:19pm UTC](https://mworks.discourse.group/t/evaluating-expressions-in-trigger-watch-variables/454/1 "2016-04-01T14:19:29Z")
Hi Chris, Not sure if this is known behavior, but it looks like putting an expression in the “trigger\_watch” fields breaks the circular fixation point stimulus - it outputs false into the trigger\_flag variable no matter the value of the expression. It’s not holding me up - as a workaround I created a dummy variable which gets updated whenever the independent variable in the expression gets updated. I haven’t tested the rectangular fixation point stimulus. Evan ---
**Author:** ![cstawarz](https://yyz1.discourse-cdn.com/flex031/user_avatar/mworks.discourse.group/cstawarz/32/3_2.png) [@cstawarz](https://mworks.discourse.group/u/cstawarz)\ **Post date:** [April 1, 2016, 2:30pm UTC](https://mworks.discourse.group/t/evaluating-expressions-in-trigger-watch-variables/454/2 "2016-04-01T14:30:55Z")
Hi Evan, Yes, that is known behavior, and it applies to both fixation point types. Changes to the independent variable(s) don’t cause the expression to be re-evaluated. Had you not already thought of that workaround, I would have suggested something similar. Cheers, Chris ---
**Author:** ![cstawarz](https://yyz1.discourse-cdn.com/flex031/user_avatar/mworks.discourse.group/cstawarz/32/3_2.png) [@cstawarz](https://mworks.discourse.group/u/cstawarz)\ **Post date:** [July 19, 2022, 10:05pm UTC](https://mworks.discourse.group/t/evaluating-expressions-in-trigger-watch-variables/454/3 "2022-07-19T22:05:16Z")