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Event-Related EDA Analysis

AcqKnowledge® includes a fully-automated suite of tools for Event Related Electrodermal Activity applications. The analysis is based around the timing marks that come from stimulus presentation systems (Superlab®, E-Prime®, DirectRT®, MediaLab®, Inquisit®, Presentation®, etc.), plus virtual reality (Vizard®), and the SMI® Eye Tracking stimulation software. The stimulus presentation systems output TTL event marks to pinpoint when discrete stimuli are presented to a subject (visual cue, tone, image, mechanical, electrical, olfactory, light stimulation, etc.)  and the MP device records them on digital channels. The Digital Input to Stim Events utility converts the TTL pulses into usable stimulus events for further analysis.

Digital Input to Stim Events identifies and labels stimulus events corresponding to any combination of TTL pulses on the digital inputs. A light bulb icon is placed in the global events bar, the event is labeled with the stimulus event type, and the mouse-over tag includes the event time. All event information is accessible and exportable from the Event Palette. The utility can also convert manual events located in any of the analog channels to stim events.

Once a file contains stimulus events, it’s possible to run the Event-Related EDA analysis routine.

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Details

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A file must contain both tonic and phasic EDA waveforms. AcqKnowledge will either create a phasic skin conductance response signal from the tonic skin conductance level data, or use an existing waveform.

AcqKnowledge EDA analysis dialog

If a phasic signal is not present in the file, AcqKnowledge uses either baseline smoothing or high pass filtering to construct a new Phasic EDA channel. This routine is automatically included in both the locate SCR and Event-Related EDA routines.

Tonic and Phasic EDA data

Once a file contains both a phasic and tonic waveform, the software identifies skin conductance responses and visually scores the waveform. All SCR events are marked on the tonic waveform. The software marks the event onset, SCR point of max response, and waveform end. Responses can also be manually adjusted using the event marking tools.

AcqKnowledge will then look for stimulus events and determine whether an SCR occurs within a user-defined time window after the stimulus was presented to the subject. If an SCR is present, the software will mark it as a Specific Skin Conductance Response (SSCR) by coloring the water drop red and displaying a flag with the stimulus type above the water drop. Skin conductance responses that fall outside of the window are marked as Nonspecific Specific Skin Conductance Responses (NSSCR). Nonspecific responses do not have the red water drop present, they just have the blue drop to identify a skin conductance response.

Specific and nonspecific SCR

Analysis Results

The analysis provides the following results.

  1. Event-Related SCR data: Includes Specific SCR (SSCR) responses that fall within the defined time window after a discrete stimulus. Measures output include:
    • Stimulus Delivery Time
    • Skin Conductance Level
    • Response latency
    • SCR Amplitude
    • SCR rise time
    • SCR Size
    • SCR Onset
    • Stimulus Type
  2. Unmatched Stimulus Event Summary: Includes all discrete stimulus events that were not matched with a valid SCR response (NSSCR). The table displays event time and stimulus type.
  3. SCR Frequency Analysis: Includes each stimulus type, the frequency of specific and nonspecific responses along with the predefined epoch width (user defined epoch width).
  4. Stimulus Matching Summary: Includes the amplitude, magnitude, total number of matched, total number of non-matched, and frequency percentages for each stimulus type.

Videos

EDA - SCR Event Related Analysis

Focus Areas | Use Find Cycle to Create around Digital Events

Digital Input to Stim Events

Support

Application Notes

Knowledge Base

Hardware Packages   |   Event-Related EDA Analysis

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