EthoVision’s trial control settings allow you to plan sequences of events during a trial with specified delays and durations. However, sometimes it’s beneficial to introduce randomness into those sequences for experimental variability.
The simplest method is to create multiple Trial Control Settings profiles and randomly assign one per trial. This maintains simple trial logic and allows you to group trials for analysis based on profile selection.
You can also incorporate randomization into a single profile using the methods below.
Use the Time Condition block with a random duration instead of a fixed delay:
To randomly select between different events (e.g., a tone vs. noise stimulus), you can use Trial Control Variables.
Here is an example where a random number is used to select between a noise or tone stimulus, followed by a randomized delay:
To ensure a fixed number of stimulus presentations (e.g., 5 tone and 5 noise), use additional variables to count how many times each stimulus has been shown. If a stimulus reaches its limit, the logic switches to the other option.
This structure adds counting logic to the random selector:
Call the sub-rule a fixed number of times (e.g., 10) to distribute stimulus presentations randomly but evenly:
While zones are common triggers, EthoVision XT can also initiate events based on:
This makes it possible to design complex, behavior-driven experiments using randomized and conditional event sequencing.