Electrodermal Archives - Page 4 of 4

Understanding Stimulus Presentation Studies

Stimulus presentation studies are an important aspect of modern research that record and organize a participant’s reactions and physiological data to various inputs. These studies are commonly used in neuromarketing or psychophysiological experiments. First off, what is stimulus exactly? Put simply, a stimulus is a sensory input delivered to a participant with the purpose of eliciting a particular response. These stimuli can consist of images, words, lights, sounds, virtual reality, scent, or even mild electrical impulses.

The idea is to present varying types of stimulus to a participant at expected or unexpected intervals and record his/her response. For example, a collection of images might be presented (one at a time) ranging from pleasant (say an impressive vista) to neutral (say a street scene) to unpleasant (possibly a striking snake or other “fight or flight” image). Programmable stimulus systems (such as E-Prime or SuperLab) to present the stimuli, and can be used with a Chronos or M-Pod response keypad that the participant presses, each key representing a different response (e.g., pleasant image = press Key 1, unpleasant = press Key 2, etc.). A physiological signal commonly gathered from the participant is electrodermal activity (EDA), which measures the perspiration generated in a participant’s palms or fingertips. This “eccrine activity” has a strong correlation with emotional responses. For studies involving visual stimuli, a camera may be used to record the participant’s facial expressions. The expressions are simultaneously recorded and categorized using software such as FaceReader.

Stimulus experiments are generally set up using the hardware and software of the stimulus system and the resulting physiological data and stimulus markers recorded using a data acquisition system, such as BIOPAC’s MP160 with STP100C, MP36, or Smart Center Systems. These systems include AcqKnowledge or Biopac Student Lab life science software and the MP data acquisition units that interface with the stimulus hardware.

In practice, setting up stimulus studies is easier than it sounds on paper. The parameters and stimulus types are set up via drag-and-drop-interfaces in the E-Prime or SuperLab software, and the hardware interface set up using an I/O or USB connection between the stim hardware and the computer. The stimulus and BIOPAC data acquisition software can easily reside on the same computer, as can all stimulus and BIOPAC data acquisition hardware.

Stimulus studies can range from a simple setup, such as a participant responding to a sound for reaction time studies, to more randomized studies utilizing different types of stimulus delivered at varying pre-programmed intervals.

When the study is completed, data can be analyzed in AcqKnowledge software, and the various stimulus/responses organized automatically using AcqKnowledge’s automated Stim-Response Analysis routine.

For more information about conducting Stimulus studies using E-Prime, SuperLab, and AcqKnowledge software, we invite you to view the following free webinars and video tutorials:

Stimulus Presentation and Event Mark Up with E-Prime

Stimulus Presentation and Event Mark Up with SuperLab

AcqKnowledge Stim Synchronization and Analysis

Focus Areas – Automatically Create Using Define Between Events

BIOPAC offers a wide array of wired and wireless equipment that can be used in your research. To find more information on solutions for recording and analyzing signals such as ECG, heart rate, respiration and more using any platforms mentioned in this blog post, you can visit the individual application pages on the BIOPAC website.

Holiday Happiness Part 2: Sounds, Smells, and Self-Reflection

In a previous post, we discussed the stress-reducing benefits of loving interactions with close friends and family during the holiday season. In addition to family, there are many mood-shaping habits and activities that characterize the holidays: the smell of home-cooked meals, seasonal music, and reflection on the past year, to name a few. But do these have a real impact on happiness?

In a psychophysiology study, Matsunaga, et al., tested odor effects on autobiographical memory recall. The researchers introduced several odor stimuli to participants and measured their psychological and physiological reactions. Heart rate and skin conductance were recorded throughout the experiment with a BIOPAC data acquisition system. The odor stimuli resulted in decreased heart rate, increased skin conductance level, and an increase in positive mood states.

Another article tested the effects of meditation on emotional regulation. Participants completed emotional measures before and after a meditation intervention, and had their ECG, respiration, and blood pressure recorded using a BIOPAC MP unit. The meditation correlated with greater participant emotional regulation, as suggested by lower heart rate and respiration.

In addition to meditation and smell, Harmat and Eerola have found music to also be emotionally significant. Participants listened to a musical piece, and then responded to a questionnaire about their emotional state. In addition to measuring pulse rate and facial expressions, the BIOPAC Research System and EDA Amplifier were used to record skin conductance while participants listened to the stimulus. The results found that music samples evoked several emotions, including nostalgia and happiness.

This research suggests that we can affect happiness using subtle techniques that are part of everyday living. To read more studies about psychophysiology and stress reduction, visit the BIOPAC publication page.

BIOPAC offers a variety of equipment that can be used in studies similar to the ones presented. To find more information on solutions for recording and analyzing signals such as skin conductance, ECG, heart rate, respiration, and EDA using the MP160/MP150, and other platforms, you can visit the individual application pages on the BIOPAC website.

Holiday Happiness: Gratitude or Gifts?

Studies investigated the anxiety of gift-giving, the effects of social support in stressful situations, and what impact meditation has on heart rate, ECG, and blood pressure.

December has arrived, and for many the holidays bring a rush to check items off of a long shopping list for parents, siblings, friends, in-laws, and many more. Often we struggle to find that “perfect” gift, but are the physical goods we exchange the true source of the warmth and happiness that characterizes the season?

An article by Nomura investigated anxiety induced by gift-giving. To test this, EDA data was recorded with a BIOPAC data acquisition system and STP100 while participants responded to stimuli. The participants visualized a specific relative while being presented with potential gift options, and were asked how likely they were to purchase the potential gift for that relative. The data found that people who self-reported thinking of in-laws were the most stressed, while those who reported thinking of children or same-gender friends were least stressed.

A psychosomatic study by Inagaki and Eisenberger found that mental and physical well-being benefit from forms of social support. They tested this by administering mild shocks with the BIOPAC STMISOLA to male patients who held the hand of a female partner lying in an fMRI. The results suggest that this support (hand-holding) provided possible stress-reduction for both the male and female participants.

Another article on nonverbal communication and well being by Shaltout, et al. tested the effects of meditation and the subsequent ECG, blood pressure, and heart rate effects. The BIOPAC ambulatory BioHarness and NIBP Blood Pressure System gathered data while participants underwent several mediation episodes, during which they were instructed to focus on loving kindness towards a subject. The results found that participants had decreased heart rate.

Research suggests direct, loving interactions with those who are close to us have many stress-reducing benefits. So when you are shopping for gifts, remember that spending time is more important than spending money. To read more studies about love and stress reduction, visit the BIOPAC publication page.

BIOPAC offers a variety of equipment that can be used in studies similar to the ones presented. To find more information on solutions for recording and analyzing signals such as EEG, EMG, respiration, and EDA using the MP160/MP150, MP36, and other platforms, you can visit the individual application pages on the BIOPAC website.

BIOPAC Systems, Inc. provides life science researchers and educators with data acquisition and analysis systems that inspire people and enable greater discovery about life. Visit us at www.biopac.com.

The Physiology of Consumer Buying Habits

On “Black Friday” in the US, shoppers will come out in search of great deals, and researchers can measure the many physiological factors that motivate shoppers other than deals and price cuts.

Black Friday is one of the most exciting days for consumers in the United States. With the holidays right around the corner, significant deals and price cuts incentivize people to do bulk gift shopping. But is price the only factor influencing shoppers to dedicate hours waiting in line for a product?

In a neurophysiology study by Alexander et al., researchers found that participants who received a coupon while shopping online had a significant increase in oxytocin and a decrease in cortisol. A BIOPAC research system was used to gather ECG, respiration, and skin conductance data while the participants browsed a commerce website.

Another article by Ha-Brookshire and Bhaduri measured ECG response to stimuli that tested consumers’ perceived trust of businesses. The BIOPAC MP36R was used to record participants’ heart rates while they read negative reviews of an apparel business. The results found lower heart rate and less trust were correlated with the less favorable comments.

Conversely, a consumer research study by Langner et al. found that consumers’ love of brands is similar to their love of friends. Signals measured included EDA, EMG, ECG, and BPV, and were recorded by BIOPAC MP160/MP150 hardware to measure arousal levels while participants viewed different brand and interpersonal stimuli.

BIOPAC offers a variety of equipment that can be used in studies similar to the ones presented. To find more information on solutions for recording and analyzing signals such as EEG, EMG, respiration, skin conductance using the MP160/MP150, MP36, and other platforms, you can visit the individual application pages on the BIOPAC website. If you are interested in reading other related studies, visit the publications page on the BIOPAC website.

The Physiology of Election Decision-Making

The psychophysiological factors of stress, the behaviors of others, and of introception can play major roles in decision-making, and BIOPAC systems provide measurements of how physiological factors such as these influence decisions.

People experienced varying stress levels because of the 2016 US presidential election. There are a variety of factors that can impact voting behaviors and decision-making. Several recent studies using BIOPAC systems investigated the psychophysiological effects of stress, the behaviors of others, and introception on decision-making.

Stress has been shown to be very influential in decision-making. In their study, Yamakawa, Ohira, and Mastunga Isowa (2016) investigated effects of acute stress and risk taking in decision-making. Participants were asked to perform a decision-making choice where they either kept or bet the money they were given. Cardiodynamic activity was measured with ECG using a BIOPAC MP system. Results suggest that with an increase in cortisol, adrenaline, heart rate, and subjective stress, participants were likely to make fewer risky choices. So, high levels of stress may be key in helping make better decisions when selecting a future president.

Perhaps it’s not stress that will influence the choice of the next POTUS (President of the United States), but rather the behaviors of others. Work by Bault, Joffily, Rustichini, and Coricelli (2011) sought to compare private and social decision-making to discover the effect of social comparison on risky choices. The objective of the study was to understand more about how individuals evaluated the outcomes of their decisions in private as opposed to in a social context. Combining data from functional MRI (FMRI) and skin conductance recordings, subjects’ reactions were measured using a BIOPAC MP150 System. Researchers found that participants took significantly longer to make a decision in a social setting than in a private one.

In the end, many feel that it is important to listen to your heart when deciding who you find qualified to be the next president. A study by Dunn et al. (2010) examined whether introception moderates the coupling of bodily responses to emotional experience and intuitive decision-making. Bodily response and heart rate were recorded using a BIOPAC Research System and electrodes to measure introception through changes in heart rate. Researchers found that introception was not related to arousal, valence ratings, or heart rate response to images.

For more information on BIOPAC’s wide range of tools for recording, displaying, and analyzing physiological measurements from human and animal subjects including respiration, heart rate variability, ECG and EDA, visit BIOPAC’s psychophysiology page and view BIOPAC’s full line of electrodes, amplifiers, and wearable, wireless transmitters and loggers.

Start the First Class with EDA and Emotional Responses!

By Howard Iver Thorsheim, Ph.D., St. Olaf College. I wanted to start the first day of my class with an activity that would engage students’ curiosity and enthusiasm, to set the stage for introducing the course and going over the syllabus!

By Howard Iver Thorsheim, Ph.D., St. Olaf College

Howard Iver Thorsheim is Professor of Psychology and Neuroscience at St. Olaf College, Northfield, Minnesota, USA. In these blogs he offers his first-person insights into effective teaching techniques gleaned from a combination of scholarly research and over 40 years in the classroom.

I find Electrodermal Activity (EDA) to be a great way to demonstrate psychophysiology measurement at the beginning of a course: students easily understand it. It takes little time to set up and record because it only involves two sensors on the finger tip pads. It works every time as a “window” to emotions with clear responses to a variety of stimuli (e.g., visual, auditory, gustatory, olfactory).

I show students a picture of a rock climber climbing a cliff, then ask them to jot down some notes of what they might feel when climbing like the woman pictured, and then buzz with a person sitting next to them about what they wrote. I ask for a show of hands of who has mentioned the bag hanging from the climber’s belt. Depending on the amount of time I choose to devote to the activity, I lead the entire class through a number of probing questions; for example:

“Who knows what the bag is for?” (Chalk for fingers.)

“Why does the climber use chalk?” (Reduce slipperiness from sweat.)

“Why do fingers get slippery?” (Emotion.)

“What other people encounter emotion daily?”

I then set the stage for EDA: changes in skin conductivity are due to the amount of sweat in sweat glands of the skin, which are produced by the sympathetic branch of the autonomic nervous system responding to emotion.

I explain to the class that I will be the first volunteer, and guarantee that no shock is involved using BIOPAC equipment. I connect electrodes on the volar pads of my index and middle fingers, and take a deep breath, which will generate EDA. Then I tell the class I will think of emotion-producing situations, and ask them if they can see any EDA detected by the equipment. There will be a few good chuckles because in anticipation of doing so, my response will already appear. Two of several easy classroom measurements of EDA include latency (about 1 to 3 seconds between a stimulus and beginning of the electrodermal response), and peak amplitude (the maximum size of the response). My eBook Doing Psychophysiology–Getting Started on the Apple iBooks Store has a graphic narrative and a one-minute video explanations about EDA, as well as other psychophysiology measures you can show your students. The Biopac Student Lab system also includes two lessons in which students can engage in interactive learning activities while measuring EDA; a lesson on the principles of biofeedback and one on the standard physiological measures of a polygraph.

An excellent summary of Electrodermal Activity is provided in the following chapter:

Dawson, M. E., Schell, A. M. & Fillion, D. L. (2007). The electrodermal system. In J. T. Cacioppo, L. G. Tassinary, & G. G. Berntson (Eds.). Handbook of psychophysiology (3^rd ed. pp. 159-181). New York: Cambridge University Press.

Learn more about BIOPAC’s education solutions, including complete teaching systems for psychophysiology and the life sciences. BIOPAC also provides a wide range of research systems for recording, displaying, classifying, and analyzing psychophysiological measurements.

Professor Thorsheim is a licensed Psychologist, educator, and author. He has published or presented over 125 papers, journal articles, books, book chapters or monographs, and received a patent in 1985 as a co-inventor for an educational book design with interactive elements. His work has been funded by marquee foundations across the globe. His most recent work is Doing Psychophysiology: Getting Started, available from Knowledge Growers, Inc., available as an iBook download in 51 countries.

Electrodermal Activity (EDA)

Typically, EDA is measured as skin conductance and a small direct constant voltage (0.5 vdc) is used as excitation source across the skin electrodes.

By Alan Macy, BIOPAC Systems, Inc.

Electrodermal activity measurement is subject to electrically-related characteristics of the skin. There are two phenomena associated with this type of skin activity. One is skin potential, which is a self-generated potential intrinsic to the skin. This potential is a consequence associated with dissimilar skin layers placed in proximity coupled with the presence and movement of interstitial fluids. An evoked skin potential response is called the sympathetic skin response. This change in skin potential can be evoked by electrical, auditory or magnetic stimulation. The other phenomenon associated with skin electrical activity can be measured when a stimulation (excitation) current is injected through, or a voltage is applied across, attached skin electrodes. The current or voltage stimulation is typically at constant (DC) level, or at low frequency, because the skin impedance is high. The application of excitation current or voltage produces a corresponding voltage or current, respectively, that changes over time subject to physiological state. In these cases, the skin’s resistance, impedance, conductance or admittance is being measured, corresponding to the type of electrical stimulation used.

EDA Measurements – subject to electrical excitation type:

Skin Resistance – Direct Constant Current (not commonly used)

Skin Conductance – Direct Constant Voltage (most commonly used)

Skin Impedance – Alternating Constant Current (not commonly used)

Skin Admittance – Alternating Constant Voltage (sometimes used)

Typically, EDA is measured as skin conductance and a small direct constant voltage (0.5 vdc) is used as excitation source across the skin electrodes. The skin admittance method (alternating constant voltage excitation) may provide some advantages in measurement in that this method does not polarize the skin electrodes during EDA recording. Skin conductance is usually measured in units of “Siemens” although sometimes “mho” is used. The unit “mho” comes from the reverse spelling of “ohm”, the unit of resistance. One mho equals one Siemen. The conductivity of the skin is small, so values are given in microsiemens (uS) or micromhos (umho).

Changes in the electrically-related characteristics of the skin is correlated to eccrine sweat gland activity. Eccrine glands are in nearly all skin locations and are found, in highest concentrations, on the palms of hands, fingertips and soles of the feet. EDA, measured as skin conductance, is a physiological signal that indicates increased sympathetic nervous system (SNS) activity. This aspect of EDA is representative of changes in the electrical conductance of the skin due to eccrine (sweat) gland activity. SNS activity increases sweat gland secretions. Eccrine glands only receive activation signals from the SNS, so increased EDA is an indicator of increased arousal.

There are two aspects to skin conductance measurements, namely phasic and tonic. Tonic value is the average skin conductance level (SCL), that is relatively consistent over time, and is related to arousal. The phasic component of skin conductance is the change of the skin conductance, over a short time period, in reaction to a stimulus. For a skin conductance response (SCR), the skin conductance rises in a short time period and then returns to tonic levels. SCRs are characterized by four different parameters: the response peak amplitude, latency of response, rise time to the response peak, and recovery time after peak.

For more information on BIOPAC’s EDA research solutions, including real-time live raw EDA data as well as real-time filtering or calculation channels including High-pass filtered/AC Coupled EDA, visit BIOPAC’s EDA Analysis page or view BIOPAC’s full line of electrodes, amplifiers, and wearable, wireless transmitters and loggers.

Additionally, a link to a recently updated EDA SCR Analysis Guide for Psychological Experiments came be found here.