Psychophysiology Introduction
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[edit] Introduction
For purposes of these pages, "psychophysiology" ("PP" for short) refers only to those measures we can collect at the ACL, using, for the vast majority, Biopac technology. The more popular PP measures we have are EMG (facial muscles) and GSR (i.e. skin conductance), as well as others such as respiration, temperature, and blood pressure.
Some parts of a PP experiment that the experimenter should be familiar with are (click on each link):
Simplistically speaking, you need the Hardware to measure and collect the PP data, the Software to record and save them, the Experiment that the participant runs, and then Analyse them to answer some psychological question.
Before you dive headlong into running your participants, you should be prepared to answer all sorts of questions, including but not limited to:
- Which PP measures do I want to collect?
- Why? What are my expectations in terms of results? What would they mean to the research question?
- Is the equipment available?
- Experimental logistics: How long will the equipment set up take? Is it comfortable enough not to interfere with the experiment? What will the Ethics Board think? Et cetera.
- What settings do I need to use for certain PP measures (e.g. gain, filters, sampling rate, minimum resistance)?
[edit] High-level Cartoon
This is roughly how Psychophysiological data are collected:
The participant is running your E-Prime experiment on the computer while connected to the PP transducers, which converts PP signals to analog data (e.g. voltage drop across skin/hand) and sends them to the Biopac machine. However, PP data aren't very meaningful unless you know what's causing them (i.e. what's happening in your experiment). So your experiment must send notifications, or markers, to indicate when a certain part of the experiment is occurring (e.g. a negative valence IAPS picture event). Of course, there must be multiple types of markers to reflect these different parts or conditions of your experiment. The Biopac machine treats both PP data and the experiment markers as different channels of data. This synchronizes the PP data to what's happening in your experiment. These data are then sent to the Computer where they are recorded by Biopac software.
[edit] Other Resources
- Locate the Handbook of Psychophysiology by Cacioppo et al. in the lab. It's laughably large, but the amount of useful information it has is not funny.
- Carefully read the methods of papers relevant to your research. They should point you to justifications for why particular PP measures are used and, if they’re nice, what settings they used for data gathering and analysis.
