Measuring Neural and Behavioral Activity During Ongoing Computerized Social Interactions: An Examination of Event-Related Brain Potentials

Research on social exclusion has grown tremendously in recent years. As the field expands, it is imperative to develop sophisticated methodologies allowing for the simultaneous measurement of neural and behavioral outcomes during social exclusion. This protocol utilizes event-related brain potentials to record ongoing neural activity during computerized social interactions.

The overall goal of this procedure is to obtain measures of both neural activity and self-reported feeling states during computerized social interactions. This is accomplished by first creating the computerized stimuli for the program. The second step is to program the computerized cyber ball social interaction.

Next, the participant's neural activity is recorded during the social interaction. The final step is to process the neural data offline following the completion of the cyber ball protocol. Ultimately, the event related cyber ball protocol is used to show the neural activity associated with each moment within an ongoing dynamic social interaction.

The main advantage of this technique over existing methods like questionnaires after interaction or FMRI technology, is that this technique allows for the examination of each type of event within an interaction as well as the dynamic neural activity within each event and across events. To begin, use a photo editing program to create individual images for each portion of the throws within cyberball. Break down each of the throws from player to player into the individual throw frames that are shown one after another.

Next, add any labels, names, or pictures to each individual throw frame. Include an image to represent the human participant as the bottom player on the screen. Note which frame in each throw sequence is the informational frame for that throw.

This is the first frame within the throw sequences that provides information to the players about the specific destination of the throw. Ensure that there are throw sequences creating a throw from each player to each other player on the screen. Each throw sequence should have the same number of throw frames and the informational frame should be noted on each.

The next step is to create a sequence file using stimulus presentation software to detail the exact sequence of events within the cyber ball social interaction. For the sequence file, specify the specific throw frames, the timing of the frames on the screen, and the sequencing of the frames. Also define the nature of the event, the response required by the human participant and the overall order of events.

To create the desired interaction, specify all of the above-mentioned specifics within the programming code. For each event within the sequence file and repeat the steps for each sequence. File created Next, order each of the throw frames in the correct sequence within the sequence file so that the first ball toss is completed without error from one player to the other.

Create similar ordered sequences in the file for each type of throw among the players so that each type of throw is represented in the sequence file. Insert an event related marker. Each time an informational frame is presented in the sequence file so that the presentation of this frame can be marked in the file.

Saving the participant's neural activity code this marker to represent the nature of the event by using numbers to represent the players. If the left player is player one, the bottom player is player two, and the right player is player three. The code one to three is used to represent a throw from the player on the left to the player on the right to allow the human participant to freely select which player will receive the next throw following the human participant create.

If then statements, the human participant will have a response pad or mouse to select the next action. After receiving a ball tos, create loops and if then statements within the sequence file to represent the desired game action and allow the program to appropriately move to the next event regardless of the selections of the human participant. Next, initiate counters within the program to change the nature of the game so that the program does not become apparent to the human player.

Use these counters to switch the game action and remove patterns of play throughout the game to better give the appearance of spontaneous live play among players. Lastly, develop different sequence files in order to study different types of social interactions. Make these interactions largely inclusive for exclusive or partially inclusive or exclusive for the human participant depending on the nature of the research question.

To begin the neuro electric recordings, prepare the participants for electroencephalography or EEG in accordance with the guidelines of the Society for Psychophysiological research. After fitting the electrode cap on the participant's head and preparing the electrodes, reference the electrodes online to an electrode placed at the midpoint. Next place centered silver, silver chloride electrodes above and below the right orbit and near the outer campus of each eye and collect vertical and horizontal bipolar electrographic activity.

To monitor eye movements record EEG activity using EEG analysis software in order to further process the neural data. When ready to begin testing, instruct the participant to sit comfortably and to respond with a button press to determine where to throw the ball after they receive a throw in the interaction. Start the cyber ball program on the stimulus presentation and start recording on the EEG data acquisition, computer record EEG activity during the entire duration of the cyber ball interaction.

Once the interaction stops, stop recording EEG data. After the session, remove the EEG cap and provide the participant with a complete debriefing about the nature of the cyber ball protocol and the purpose of the social interaction manipulations. To begin processing the data correct for eye blinks.

Using a spatial filter, this multi-step procedure generates an average eye blink using principle component analysis to create a filter that is specifically sensitive to eye blinks. Next, create stimulus locked epochs relative to the event marker that was inserted in the continuous EEG file. Run these epochs from minus 900 milliseconds to 1800 milliseconds relative to the inserted marker, which is equivalent to the entire duration of each six frame throw using the data transformation option correct for baseline differences between the epoch by removing the average pre stimulus baseline activity from each LOPAs.

Filter the epochs and reject any epochs with electrical artifacts that exceed plus or minus 75 microvolts. Next, average the neural responses together for each event type within the cyberball task blocks, combine the various event types to create three major event categories. Throws to the participant from either other player throws from the participant to either other player and throws not including the participant between the two other players.

Lastly, combine the events from the computerized players into the event types of most interest throws to the human participant or inclusionary and throws away from the human participant or exclusionary. This graph shows representative ERP wave forms by throw type and block type. The left graph displays waveforms at FCZ, which is a frontal, central midline site, and the right graph displays waveforms at pz, which is a parietal midline site.

The graph shows differences in the two ERP components, the N two and P three based upon the nature of the social event, and it's not the overall nature of the social interaction. Alterations in neural activity during the course of the social interaction can be applied to different ERP components and electrode sites as shown by the waveform for FCZ and pz. Both the N two and P three components exhibit larger amplitudes earlier in the exclusion process compared to later in the exclusion process Following this procedure.

Other methods like varying the nature of the interaction to include more players, different degrees of inclusion and exclusion, or allowing participants to witness exclusion before engaging in a social interaction can be performed to answer additional questions like, how quickly do patterns of neural activity recover from varying episodes of exclusion? Does the number of partners influence exclusion related activity and does witnessing exclusion alter one's own neural reaction to exclusion?