The Max Planck Institute for Empirical Aesthetics is dedicated to empirical research—that is, research in which the conclusions of scientific studies are drawn strictly from concrete data that are empirical and thus verifiable. Such empirical evidence can be obtained by means of both quantitative and qualitative research methods. From online questionnaires to laboratory studies, where a variety of different instrumental research techniques can be used: depending on the scientific question, data collection is carried out with the appropriate methods, a selection of which are presented here.
Regularly used Methods
In many of our studies we are interested in how individuals are affected by particular stimuli. Self-reporting is a method often used for measuring subjective experience. In most cases, it involves presenting participants, either on paper or via computer, with specific questions combined with an answer scale. Self-reporting is also usually used for collecting general information about the individual (e.g. age or schooling) and aspects of the study (e.g., familiarity with the stimuli). In some studies, we also conduct interviews. In simple and short interviews, the answers are transmitted directly; in longer and more complicated ones, the questions and answers may also be recorded and analyzed later.
Reaction Time Test
The reaction time test is used to determine how quickly an individual responds to a particular stimulus (e.g., a tone or a symbol) by pressing a key. Such measurements are usually part of a long series of stimulus presentations, for each of which the reaction time is tested.
In order to register acoustic stimuli—from phonemes to musical performances—or, alternately, to generate them, we use different kinds of microphones to record sound.
The nerve cells in the brain are in constant communication via electrical currents, which can be measured with the help of electrodes placed on the scalp. In an EEG, such electrodes are woven into a cap that the participants wear. In order to obtain a reliable measurement of the brain currents, the resistance between the scalp and the electrodes must be reduced by filling the electrodes with a water-based, saline gel. EEG is particularly suitable for recording immediate reactions of the brain waves to external stimuli (e.g., to images or sounds). This method is painless and safe.
Magnetic Resonance Imaging (MRI)
MRI measurements are performed using a tomograph, a tubular apparatus, inside which a very strong magnetic field is built up to create images of the brain. Because of this strong magnetic field, people who have non-removable metal on or in their bodies, such as implants, cannot take part in an MRI measurement in order to exclude the risk of injury. In addition, any metal in the body would reduce the quality of the recorded images. For those without this condition, however, there are no known risks or side effects and the method is painless and safe.
The brain's electrical currents generate their own weak magnetic fields, which can be measured using MEG. This involves the participant wearing a cap mounted with sensors that can measure these very low magnetic fields. There are no known risks or side effects, and the method is painless and safe.
functional Near-Infrared Spectroscopy (fNIRS)
To measure activity in the brain or specific brain regions, an fNIRS can be used. It involves placing a hood on the head, similar to an EEG, and attaching light diodes to the scalp. The light then shines through the upper layers of the brain where it is reflected. Based on this reflexion, conclusions can then be drawn as to whether a brain region is particularly active. The method is non-invasive, painless and safe.
Image: Elisenicolegray / Wikimedia Commons licensed under CC BY-SA 4.0
Eye movements can be recorded and measured using a special camera. This makes it possible to track the length of time specific areas of an image have been viewed or which lines of text have been read again. Wearing glasses or contact lenses can fundamentally affect data quality. If you register for a study that uses this method, please bring your corrective lenses with you. If you wear both glasses and contact lenses, make sure to bring both of them with you. This method is painless and safe.
When muscles are active they, too, generate electrical currents. These can be measured using EMG, which involves attaching electrodes to the skin directly above the relevant muscle. The EMG method is used to record physiological reactions (e.g., smiling or frowning) and is painless and safe.
Abdominal or chest breathing is measured by means of a breathing belt. Placed on top of the chest and/or around the abdomen, the belt measures how far either body part expands when the subject is breathing. This method is painless and safe.
ECG can be derived with electrodes that are attached either on the collarbone or to the chest. Sometimes the measurement is also taken via a clip on the finger. ECG is used to record cardiovascular activity (i.e., heartbeat and blood flow). For our research, ECG may be of interest as a direct measurement of response to (emotional) stimuli, or as a corrective of other measurement data. The method is painless and safe. To conduct ECG on the chest, participants are given instructions and then attach the electrodes to their skin on their own in private.
A miniature camera in a special casing can be used to optically record whether and when goose bumps form in response to (emotional) stimuli, such as music or images. Several of these special cameras are attached to a subject's calves, forearms, or neck with a belt. This method is painless and safe.
Skin Conductance Sensor
The level of skin conductance can be measured using electrodes glued to the fingers. The conductivity of the skin depends on the activity of the sweat glands. This changes in response to the activity of the sympathetic nervous system, which is related to emotional states. This method is used as a complement to self-reporting data when measuring emotional states.