Preventing Yoking

Hi guys,

I'm building a signal detection experiment in which stimuli are randomly selected from two lists. For some of the trials, the stimuli need to be yoked. For other trials, I want to ensure that the stimuli are NOT yoked.

In other words, I'm looking for a way to prevent DirectRT from selecting a stimulus on list B during random selection, if that stimulus shares its location with a stimulus on list A that was selected earlier in the same trial.

Any help is much-appreciated.

Best,


Evert-Jan