Messages and Trial Periods

Now that we have imported some data, let’s take a look at messages and trial periods.


Messages are important since they help you know when things happened during a trial, such as a display being presented. The default is for messages to be hidden from your initial view in Data Viewer (though they are not hidden in the output). To make them visible, do as in the animation below by clicking the Toggle Message Event Visibility button.

You can now see when different messages occurred during your trial. This will assist you in making sure that your experiment worked as expected.

Trial Periods

You won’t always want to output the whole of a recording from a single trial. Some parts of a trial, such as gaze contingent boxes, may not be needed for your analyses. To focus on only some parts of a trial, we can use the Interest Period options.

To change the interest period (i.e., time period of interest) being shown in Data Viewer, click the Interest Period combobox as in the animation below. You’ll then be given various options in terms of controlling when to start your interest period and when to end it. Here, since we want to start our interest period when the DISPLAY_SCREEN message occurs, we input this information.

Now you can see that the cat picture appears immediately since we’ve now filtered out the blank screen at the start of each trial. Awesome!