For over 50 years, scientists have been intrigued by how we recognize voices. Our recent study expose how emotional prosody's affect this process. Despite differences in prosody's, we found that the overall old, new effect is robust, indicating that our brains consistently distinguish familiar and unfamiliar voices.
Current experimental challenges in speaker identification arise from the commonly used, the training-testing paradigm in the past, which is not suitable for studying detailed variables affecting speaker identity processing. Ensuring that the training is thorough and effective is crucial to address this challenge. Our findings reveal, that while the LPC or the old, new effect shows differences between confident and doubtful processes, it remains robust overall.
Our paradigm is well suited for investigating the processing of familiar and unfamiliar objects with internal variations. My lab focuses on voice perception, including how pragmatically marked emotions are expressed and perceived, and how vocal information has an impact on listeners. We use EEGs and FMRI to measure these factors with a key focus on social factors such as accent, or whether the talker is AI.This study on JoVE supports our future research in these areas.
To begin, assign participant IDs and ask participants to wash and dry their hair within one hour, before participating in the experiment, mix the electrolyte gel and abrasive electrolyte gel in a one to three ratio, adding a small amount of water. Stir the mixture evenly in a container with a spoon. Prepare fine tipped cotton swabs and a dry EEG cap.
Now ask the participant to sit comfortably in a chair and inform them that the experimenter will apply the EEG cap. Provide the participant with instructions about the experimental tasks and an informed consent form for the experiment. Obtain the participant's signature before proceeding with the preparation phase.
Next, connect the EEG cap to the amplifier, which in turn connects to the EEG data acquisition computer. Use an additional monitor to check the color indicators on the 64 electrodes, as this study uses a passive cap. Open BrainVision Recorder and import a customized workspace file that has defined the recording parameters.
Click on monitor to check the impedance. Ask the participant to sit upright in a chair. Select an appropriately sized, gel-based, passive electrode system for the participant's head.
Now, dip a disposable cotton swab into the conductive paste and apply it to the holes of the cap, making sure to rub against the participant's scalp. An electrodes corresponding indicator, turning green on the EEG data collection computer signifies that it is successfully collecting optimal data. Once the indicative color for all electrodes on the screen, except for the two independent sided electrodes turn green.
Apply the side electrodes to attach the left electrode near the participant's left eye, and the right electrode near the right temple. Once all electrodes are green, place an elastic net over the participant's head to help the EEG cap fit more securely and stably against the participant's head. Then equip the participant with wired headphones.
Close the electromagnetic shielding door and guide the participant's actions through a microphone that allows communication inside and outside. Additionally, monitor the participant's movements through an external monitor, reminding them not to move their body significantly. Also, monitor the participant's progress in behavioral tasks through a behavioral data monitor.
Ask the participant to wear earphones connected to the behavioral collection computer, through an audio interface. To begin, create a new EEG recording file on the EEG data collection computer. Open BrainVision Recorder, and click on monitor to double check the impedance, followed by stat or resume recording.
Open the PsychoPy program's run experiment for the behavioral experiment. Enter the participant's ID and the corresponding block number and click okay to start the experiment. Closely monitor the accuracy of data reported on the screen after the participant completes the check phase on the behavioral data computer.
Pay close attention to the final reported accuracy of old versus new recognition. After the participant has completed all blocks, invite them to wash their hair. To clean the EEG cap, remove the residual conductive paste with a toothbrush and wrap them in plastic bags.
Once cleaned, hang the EEG cap in a well-ventilated area to dry. Copy the EEG and behavioral data onto a portable hard drive ensuring that the EEG data and behavioral data correspond.
