Create stimulus events

Channel 8, our protocol channel, tells us when the screen delivers the challenge onset signal to the participant. Below an example from the sigh task. We want to place stimulus markers into the global channel at the onset of the challenge trial (i.e. the left edge of the box signal in channel 8).

Analysis → Find cycle

Cycles/Peaks tab: Select peaks (the box) and select any threshold between zero and whatever scale you see on the right Y-axis, here 10,000).

Open

Selection tab: select “Current threshold”. This will move the selection to the beginning of the box. If you select “current peak” or “previous peak”, the selection may not consistently appear at the beginning of the box. You need to pay attention to this detail.

Open

If you select the incorrect option, it will look like this:

Output tab:

Check “Output events” under Event 1.

Maximum

Input channel 8, protocol

Output type: Stimulus/Response → Stimulus delivery

Output channel: Global

Event 2: None.

Event-related EDA Analysis

Analysis → Electrodermal activity → Event-related EDA Analysis

Select your EDA channels (if you haven’t already constructed a phasic EDA channel, select “Construct new”).

Stimulus event type: Stimulus/Response → Stimulus delivery

Stimulus event location: Global events only (meaning Global channel as output channel)

I decided here to allow a 30-second interval from stimulus onset (lightbulb) to find SCRs. The reason I chose this window to be so wide is that the stimulus presentation window is a few seconds long by itself and the subject may take a few seconds to take the sigh.

Export as spreadsheet only.

Excel output

The resulting excel spreadsheet shows 4 SCRs. The first SCR of the first trial is missing. WHAT TO DO?