Category: psychophysiology

Eye Tracking Insights

Try Not To Blink—This Won’t Hurt

What exactly, is eye tracking? Do I have to put on a helmet or stick something unpleasant into my eye? No, nothing so invasive, and not the least bit uncomfortable. Eye tracking is the process by which eye movements are recorded for the purpose of tracking where a subject is looking, what he/she is looking at, and the duration of the subject’s gaze on a given area. Eye tracking differs from electrooculogram (EOG) in that it records where and at what the subject is actually looking, whereas EOG primarily records the movements of the eye muscles. Rather than merely recording eye movement and position, eye tracking forges an invisible yet accurate connection between the subject and the objects within the subject’s field of vision. These “visual connections” of where the subject was looking during the study are clearly visible in the resulting data, as dramatic as tire tracks on an impressionable surface.

So how does eye tracking work? Using invisible near-infrared light combined with high-definition cameras, the eye tracking system projects invisible light onto the eye and records the direction from which it is reflected off the cornea. Eye tracking software is used to calculate the exact position and focal point of the eye. The sophisticated combination of eye tracking hardware and software allows for extremely accurate measuring and analyzing of visual behavior and fine eye movements. This makes it possible to create a detailed map of a subject’s field of vision and the specific visual elements honed in on by the subject. Eye tracking data is commonly acquired in tandem with other body signals for the purpose of determining the effects of what we are looking at has on our physiology. Common signals acquired during eye tracking studies are:

  • EEG (cognitive processes)
  • EDA (alertness)
  • ECG (anxiety)
  • EMG (muscle activity, conditioning)
  • EGG (pulse, respiration, temperature)

What are researchers looking for when conducting eye tracking studies? Eye tracking data is useful in a variety of different research fields including interface usability, reading analysis, psychological and emotional response, marketing research, training, clinical vision diagnosis, and more.

Eye tracking hardware mainly comes in two flavors. Screen based eye tracking involves having a subject sit in front of a computer monitor while being presented with various types of visual stimuli. A “bar type” eye tracker records the subject’s responses and interfaces with eye tracking software to present the stimulus and store the resulting data for analysis. BIOPAC’s AcqKnowledge software version 5.0.6 and higher, along with the BIOPAC MP160, MP36R, or Wireless Smart Center system, supports fully-integrated eye tracking functionality*. Rather than having to learn a second software program, the familiar AcqKnowledge interface has been extended to incorporate the EYE-TRACK-BAR and EYE-TRACK-BAR-XL remote screen eye tracking systems.

Mobile or “wearable” eye tracking systems utilize a pair of glasses with two types of built-in cameras. One camera faces the subject and tracks eye movements, gaze path, and other parameters, and a second camera (called a scene camera) records what the subject is looking at during the study. Mobile eye tracking allows the subject to engage in independent activities outside the lab, such as driving an automobile. Additional sensors record and log data from other body signals in real time, which can be loaded into the software for subsequent analysis.

For more information about eye tracking, we invite you to sign up for our free “Eye Tracking Fundamentals” webinar to be broadcast live on November 21, 2019 at 8:00 AM PST. Did you miss it or can’t attend? No problem. Follow the same link to watch it on demand.

*Eye Tracking Integration License for AcqKnowledge required.

Please also visit the following links for information about BIOPAC Eye Tracking products.

Eye Tracking Systems

Eye Tracking License

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.

Photo by Marina Vitale on Unsplash

T4 Conference Wrap-up

August is a month of barbecues, baseball, and last-minute vacations against the backdrop of a fading summer, and the eighth month of 2019 proved to be an equally exciting time at BIOPAC, with something of a pleasant vacation thrown in. On August 12-14, BIOPAC hosted its 2nd Biennial “Tools, Trends, Techniques, and Technology” Human Physiology Conference, known as “T4” to our friends and partners around the world. This three-day event, first held in 2017, featured lively, informative sessions hosted by BIOPAC staff, partners, noted academics, and industry experts, and covered a wide range of physiological techniques and disciplines. Over 150 attendees joined BIOPAC at the 2019 T4 Conference staged once again at the beautiful University of California at Santa Barbara campus. Participants and instructors winged in from China, Australia, Germany, Sweden, Italy, Spain, U.K., Ireland, and Egypt, as well as from wide regions of the U.S and Canada to soak up the idyllic surroundings of this ocean-side campus.

The focus of BIOPAC’s T4 Conference was to provide a fun, relaxed environment while hosting nearly 40 hands-on, human physiology training workshops chaired by over 20 distinguished instructors from around the globe. One of the many conference highlights was the “Mindfulness, Meditation, and Measurement: Mindfulness Exercises in Physiological Monitoring” session, hosted by Dr. Allan Weiss of the University of Southern California and  BIOPAC Co-founder and Director of R & D Alan Macy. These sessions, conducted in two parts over a two day period were booked beyond capacity, even though the early morning fog hadn’t yet lifted from the campus skyline.

The varied additional sessions covered a range from the basics, “Setting Up Your Lab, Getting Great Data and Troubleshooting,” (hosted by Dr. Terry Blumenthal of Wake Forest University, and BIOPAC’s Alan Macy and Tim Cook), and “Creating Your Own Lessons Using BSL PRO,” (hosted by Dr. Taffeta Elliot of the New Mexico Institute of Mining and Technology), to exciting new technologies such as “Integrating Screen-based Eye Trackers with AcqKnowledge,” with Keith Jackson of BIOPAC partner company EyeTech, BIOPAC CEO Frazer Findlay, and BIOPAC Engineering Manager Ed Peterlin. Additional wide-ranging physiological disciplines were also covered, including MRI techniques, stimulation, and exercise physiology. All sessions were conducted using BIOPAC hardware and software systems, as well as platforms provided by BIOPAC partners such as Cedrus, fNIR, WorldViz, Psychology Software Tools, and CNSystems. At the end of each day, it was time to relax and unwind with a beverage of choice, a a walk along the beach, and some good conversation. Each evening featured excellent meals and camaraderie in the relaxed yet elegant environment of some of Santa Barbara and Goleta’s most stunning surroundings. After three great days of immersive sessions, it came time for everyone to part ways, having forged new collaborative partnerships and an enhanced knowledge about the full potential of BIOPAC and BIOPAC partner products.

You don’t have to wait for T4 2021 to learn more about life science data—watch Fundamentals of Physiological Data Recording now!

For a closer look at T4, and a preview of what is sure to be an exciting 2021 event, we invite you to visit our T4 Human Physiology Conference page.

Looking for additional resources, tips, tricks, and expert advice on BIOPAC and BIOPAC Partner products? Please also visit our Webinars and Video Tutorial pages.

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.

Best Practices for Recording & Analyzing Data

Over the past several years, tools and techniques for recording and analyzing physiological data recording have seen steady and marked improvement. Modern life science data acquisition systems such as the MP160 System and powerful research-grade software suites such as AcqKnowledge bring high-end physiology tools within reach of the smallest lab. Even with continuing advances and reduced margin for error, it remains prudent to follow some fundamental guidelines for maximizing data quality and clarity.

Preparation is important. First, invest time exploring the system if it’s new or unfamiliar. An overview of the documentation, training videos, and available webinars, as well as some practice runs with the hardware and software will save time and effort when the time comes to conduct a study. This will also build proficiency at identifying the differences between good and poor data.

Next, familiarize yourself with the type of electrodes and/or transducers necessary for the physiological signals you will be acquiring, which includes proper electrode and skin site preparation. For example, gently abrading the skin prior to applying electrodes is normally recommended for most signal types, except for electrodermal activity (EDA), in which case it’s vital to NOT abrade the skin beforehand. It is also helpful to wait at least 5 minutes before starting a recording, which enables the electrode gel to be absorbed into the skin, helping reduce the impedance.

Performing an impedance check to ensure that the electrodes are making good contact with the skin is also highly recommended. This task is made easier by using an Electrode Impedance Checker (such as EL-CHECK), a simple device for quickly measuring the resistance between the skin and the electrode that provides an LED readout of the skin/electrode contact quality. If the resistance is too high (indicating poor contact) proper adjustments can be made before starting an experiment.

For certain signal types, excessive participant movement can introduce unwanted artifact into the signal, resulting in poor or skewed data. Make sure the participant remains as still as possible during studies involving these signals. Using tape to attach the electrode leads to the skin and keep them from moving excessively can also be helpful.

A thorough check of the system and all connections, cameras, and other hardware is important, so that any problems with equipment or setup can be addressed in advance, thus avoiding a show-stopping issue in the midst of an experiment. This would include performing a pilot study with trained personnel in order to head off any unforeseen issues with the data collection.

Creating a lab setup conducive to a relaxed environment for the participant and technician alike will yield better results. This means eliminating clutter, noise, and other distractions that can affect comfort and attention span. Some labs even avoid having their staff wear lab coats because this can heighten participant nervousness.

Keeping detailed notes on successful lab setups is also helpful and will streamline the preparation process for future experiments. Additionally, creating and saving graph templates for regularly-repeated experiments will save further time and effort.

For more about the fundamentals of recording great data, we invite you to view this free on-demand webinar Fundamentals of Physiology Recording.

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.

Photo by John Schnobrich on Unsplash

Using fEMG for Facial Expression Analysis

Facial expressions, even at their most subtle, cover a wide palette of emotions. The study of these expressions can be approached several ways, including via a camera and facial mapping using FaceReader expression analysis software—but another common method for acquiring this type of data is through facial electromyography (fEMG).

fEMG is a relatively simple procedure that focuses on recording the activity of two specific sets of facial muscles:

  • zygomaticus major (cheek muscle used for smiling)
  • corrugator supercilli (forehead muscle associated with frowning and negative emotions such as anger, fear, and disgust).

While parsing a subject’s nuanced emotional state can be tricky, zygomaticus and corrugator muscle activity are highly reliable indicators of the physiological components of smiling or frowning. Even tiny variations of expression barely discernible in video are detectable via fEMG, as the slightest tension and release of the zygomaticus or corrugator muscles will be reflected in separate channels in the fEMG data.

So, how do we acquire good quality fEMG?

Since the zygomaticus and corrugator muscles on each side work in tandem during natural smiling or frowning, it’s only necessary to apply electrodes to one side of the face. It’s also important that one—and only one—ground electrode be used; for fEMG, ground is normally applied near the corrugator electrodes.

  1. First, the facial skin needs to be properly prepared by gently cleaning with an alcohol wipe, after which it’s recommended to apply a skin prep solution called ELPREP to enhance signal quality.
  2. Select and apply reusable (EL254, EL654) or disposable (EL513) electrodes.
  3. Before recording fEMG data, it’s also highly recommended to verify that the impedance of the attached electrodes falls between between 5 and 10 KOhms. This is easily achieved through the use of an electrode impedance checker called an EL-CHECK, which takes the guesswork out of proper electrode adhesion
  4. Connect the appropriate lead to the selected amplifier. The type of recommended electrode leads will depend on whether the setup uses

With the proper setup and equipment, acquiring great fEMG data is as easy as smiling.

To learn more, we invite you to visit our webinar page for these and other free, on-demand webinars that detail methods for recording and analysis of fEMG data:

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.

fNIRS Systems—a NIR miracle

At the dawn of the 19th century, pioneering astronomer Sir William Herschel discovered the existence of infrared radiation, which is electromagnetic radiation invisible to the human eye but identifiable via its ability to heat objects. Infrared radiation is commonly divided into three categories, near, mid, or far infrared waves. In ensuing years, infrared radiation was found to be useful for industrial, scientific, military, and law enforcement applications, such as heat signature tracking and night vision goggles. Over two decades ago, a new technology called near infrared spectroscopy (NIRS) was developed for non-invasively measuring specific aspects of human physiology using near infra-red waves. While far infrared waves lie closest to the microwave region, near infrared waves are closest in length to the visible light part of the electromagnetic spectrum, and are microscopic in size. Unlike far infrared waves, near infrared waves do not produce any heat. In fact, we can’t feel them at all. They are the small waves used by common devices such as a
remote control.

Today, near infrared waves are commonly used  for studying many application areas of human physiology, notably by the fNIRS Imaging Systems to gather precise, high-density brain function and muscle oxygenation data.

How does fNIRS work with regard to human physiology? It’s an optical technology which sends light into the tissue and records the light that scatters back via a photo-diode and sensor attached to the subject. The fNIRS continuous wave technology uses an optical window in the near infrared spectrum that enables light to pass through. For example, when you hold your hand in front of a strong white light, the tissue can appear red and almost translucent. fNIRS shines light into the skull or muscle tissue, and using special detectors, records the resulting light scatter that returns to the surface.  The light penetrates skin, bone, and alights on the brain before its return trip to the surface detectors, and accomplishes this painlessly without heat. In fact, the subject does not even feel the near infrared energy and the light is harmless. The result is startling images and functional data of the brain at work. The fNIRS Systems (ranging from Educational to High-Density versions) include fNIRsoft software for processing, analyzing and visualizing functional near infrared (fNIR) spectroscopy signals through a graphical user interface. Additionally, the fNIRS Systems work with the BIOPAC MP160 Research System and AcqKnowledge software in conjunction with other physiological signals such as ECG, respiration, cardiac output, blood pressure, electrodermal activity, and stimulus response markers. AcqKnowledge software also provides automated analysis tools for event related potentials and ensemble averaging.

fNIRS brain function application areas include workload assignment, VR,  stress, attention, geriatrics, economics, ergonomics, learning and performance, sports science, HCI, pain perception, and cognitive workload – low or high.

fNIRS Systems can also be used to measure muscle oxygenation data, including oxidative capacity, muscle load, lateral imbalances (left vs. right muscle group) oxygenated hemoglobin and de-oxygenated hemoglobin in muscle activity.

We invite you to enjoy a comprehensive free fNIRS webinar and to visit our fNIRS products page.

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.

Getting the Bands Back Together – Components of the EEG Signal

Many notable events occurred in 1929, not all of them good. The St. Valentine’s Day massacre. The stock market crash that triggered a worldwide economic crisis. The chain saw was invented. Not much good was happening in Germany either. Rampant inflation, the decline of the Weimar Republic, and the implacable rise of Nazism. But 1929 was also the year that German physician Hans Berger made an important scientific discovery that continues to influence how we study the human brain today. Dr. Berger discovered that electrodes placed on the human scalp could detect various patterns of electrical activity. After further study confirmed that these patterns were indeed related to brain activity and not mere scalp muscle artifact, scientists began to delve into the constructs of these “brain waves.” Today, electroencephalography (EEG) is still the primary method employed for recording brain function. In medical and basic research, correlation of particular brain waves reveals valuable information about sleep phases, emotional states, psychological profiles, and other mental activities. Much of this information is derived from five simple periodic rhythms, or frequencies, recorded in the EEG signal—alpha, beta, delta, theta, and gamma waves. These frequencies are known to be associated with specific degrees of alertness, affect, emotional states, and sleep. What do these frequency bands tell us about what is going on behind the gray matter? Allow us to introduce the band members.

Alpha (8-13 Hz) – Mellow Band Member

Alpha waves are associated with relaxation and calm. In general, the alpha rhythm is the prominent EEG wave pattern of adult subjects who are awake, but relaxed with eyes closed. Each region of the brain has a characteristic alpha rhythm but alpha waves of the greatest amplitude are recorded from the occipital and parietal regions of the cerebral cortex. In general, alpha wave amplitudes diminish when subjects open their eyes and are attentive to external stimuli, although some subjects trained in relaxation techniques can maintain high alpha amplitudes even with eyes open.

Beta (13-30 Hz) – Band Manager

Beta waves are related to memory, focus, and problem-solving. beta rhythms occur in alert individuals who are attentive to external stimuli, or exerting specific mental effort. Paradoxically, beta rhythms also occur during deep REM sleep. Beta waves may also be associated with “remembering” or retrieving memories.

Delta (1-5 Hz) – Supportive Band Member and Theta Rhythm (4-8 Hz) – Creative Band Member

Delta and theta rhythms are low-frequency EEG patterns that increase during sleep in the normal adult. Delta waves are associated with rejuvenation of the body through restorative deep sleep. Theta waves are more aligned with creativity and emotional connection. As people move from lighter to deeper stages of sleep (prior to REM sleep,) the occurrence of alpha waves diminishes and is gradually replaced by the lower frequency theta and then delta rhythms.

Although theta and delta rhythms are generally most prominent during sleep, there are cases when delta and theta rhythms are recorded from individuals who are awake. For example, theta waves will occur for brief intervals during emotional responses to frustrating events or situations. Delta waves may increase during difficult mental activities requiring concentration. In general, the occurrence and amplitudes of delta and theta rhythms are highly variable within and between individuals.

Gamma (> 32 Hz) – Perceptive Band Member

Gamma waves bring to the party cognition, information processing, learning, memory, and perception. Gamma waves were largely overlooked before the development of digital electroencephalography, as analog electroencephalography is restricted to recording and measuring rhythms that are usually less than 25 Hz.

A gamma wave is considered to be the “fastest” brain activity. The prominence of this wave leads to anxiety, high arousal, and stress. In optimal conditions gamma waves help with attention, focus, binding of senses (smell, sight, and hearing), consciousness, mental processing, and perception.

Research studies reported that gamma activity is involved in attention, working memory, and long-term memory processes, although excessive Gamma activity is also involved in psychiatric disorders such as schizophrenia, hallucination, Alzheimer’s disease, and epilepsy.

So in a sense, the periodic rhythms alpha, beta, delta, theta, and gamma, like the members of a tight musical ensemble, have distinct but overlapping roles for enabling the human brain to achieve wondrous things great and small that are often taken for granted.

BIOPAC Systems, Inc offers the following solutions for recording and analyzing EEG signals for research and education applications.

MP160 System with AcqKnowledge Software
EEG100D Smart Amplifier
EEG100C Amplifier Module
EEG100C-MRI Amplifier Module
BioNomadix Wireless EEG
BioNomadix Smart Center
Mobita 32-Channel Wireless EEG System
B-Alert Wireless EEG with Cognitive States Software
EPOCH Wireless In Vivo Neural Recording Systems—longterm EEG for rats, mice, or pups
Biopac Student Lab Systems—with EEG I, EEG II, and Hemispheric EEG lessons

We also invite you to enjoy our library of free EEG webinars on our Webinars page.

Understanding Stimulation Hardware

Physiology studies often involve the recording of responses from subjects who are reacting to a particular sensory input being presented, otherwise known as stimulation. The presented stimuli can take several forms, and are tightly controlled in lab environments for the comfort and safety of the subject. Different types of human and animal stimulation consist of:

  • Electrical
  • Haptic (touch)
  • Thermal (temperature)
  • Olfactory (scent)
  • Auditory (sound)
  • Visual (light, such as a strobe)

The following is an introduction to some stimulation hardware commonly used in the research market:

Stimulator Modules such as the BIOPAC STM100C is one of the building blocks for many types of stimulation protocols and create a variety of pulse and waveform outputs for nerve conduction, evoked response, audio stimulus-response, and somatosensory response studies. The STM100C interfaces with the BIOPAC MP150 or MP160 data acquisition system and a wide range of devices such as headphones, LEDs, piezo transducer for audio alarms, or haptic transducers. The device also provides technician control of the stimulus level, and works in concert with the AcqKnowledge software Stimulation setup window.

Stimulus Isolation Adapters: These adapters are added to the STM100C module and multiply the output of the STM100C by 5 or 10x to provide the desired range for nerve conduction, muscle twitch, or other studies requiring a stronger stimulus than what the STM100C can generate on its own.

The STM200 is a standalone device that interfaces with the Analog Outputs on the front panel of the Universal Interface (UIM100C) or High Level Transducer Interface (HLT100C) modules. This is a very powerful stimulator, capable of outputting up to 1 amp. It can be used for human and animal applications, including isolated tissue bath preparations.

Linear Isolated Stimulator: The STMISOLA Linear Isolated Stimulator is the most advanced and powerful stimulator offered by BIOPAC. This type of unit can handle almost any application and far exceeds most typical hardware devices in terms of flexibility and control. Typically, stimulators can only generate simple unipolar or bipolar pulses. The STMISOLA, however, can output unipolar or bipolar arbitrary waves such as pulse (single or train), square, sine, triangle, exponentially decaying, modulated envelopes, and fully user-specified types. STMISOLA can be used for Transcranial Direct Current Stimulation (tDCS) and High Definition Transcranial Direct Current Stimulation (HD-tDCS. These are forms of electrical stimulation to effect neuro-modulation in the brain.

Stroboscope: The TSD122 Stroboscope resembles a handheld flashlight and is used for visual evoked response applications and for synchronizing triggers. The unit has a range from zero to a maximum of 12,000 flashes per minute.

Haptic Stimulator: The TSD190 Haptic Stimulator incorporates an internal electromagnetically actuated plunger which can be used to mechanically stimulate a 1.5 mm diameter area of skin surface; both plunger force and travel can be infinitely adjusted between zero and a specified maximum value. This type of stimulator connects directly to the STM100C Stimulator Module and is used for tactile or somatosensory studies.

Thermal Stimulator: The STMTHERM* Thermal Stimulator is used for applying 5-second hot or cold temperature pulses to a  4 cm x 4 cm skin area. AcqKnowledge software controls the actual output from the MP160 data acquisition unit and the stimulator hardware multiplies the signal to achieve the desired voltage or current levels.

Auditory Stimulator: The OUT101 Tubephone is used to deliver aural stimulus in the form of clicks or tones for auditory evoked responses studies such as auditory brainstem response (ABR) and resembles a tube, which is worn in the ear. It connects directly to the STM100C Stimulator Module.

We hope the above thumbnail sketch serves as an introduction to various stimulator hardware and common stimulation protocols. Please visit the above linked content for more in-depth information.

We also invite you to view our free webinar, Stimulation Techniques for Researchers, available on-demand.

*STMTHERM Thermal Stimulator will be available soon! Stay tuned.

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.

The Face of Facial Expression Analysis

Say you’re in a situation where it behooves you to keep a poker face. At an auto dealership negotiating a price on the new car of your dreams, or sitting across from your boss trying to make a case for a promotion. Your heart is pounding, sweat is forming in the crevasses of your palms, yet you need to keep yourself in check and not betray your excitement or apprehension. How skilled are we at masking emotions really? Emotions affect everyone in daily life, and play a key role in non-verbal communication. They are essential to understanding human behavior. A growing area of research is geared toward classifying and analyzing human emotions for a variety of studies, and methods for acquiring this data have become increasingly reliable and sophisticated. How do these studies work, and how is something as amorphous as the smallest twitch of a facial expression accurately recorded?

Facial “emotion reading” software such as FaceReader can detect minute variations in facial expressions by analyzing key points on the face (over 500) and has been “trained” with more than 10,000 manually annotated images to enhance facial modeling accuracy. Using this vast classification library, the input is distilled into six basic or universal emotions, (happy, sad, angry, surprised, scared, disgusted, or neutral.) Facial expression data is non-invasively gathered in real-time via a still or video camera, so no electrodes or leads are necessary.

But these refinements are more than skin deep. Additional tools for further quantifying facial expression data are commonly available. “Action Units” is the term used to describe individual or group facial muscle activity. The FaceReader Action Units add-on module allows automatic analysis of a selection of 20 common Action Units (such as raising of cheeks, wrinkling of nose, dimpling, and lip tightening) to measure affective attitudes (such as interest, boredom, and confusion).

Facial expressions can be visualized as bar graphs, in a pie chart, and as a continuous signal. Using FaceReader integrated with AcqKnowledge software and the MP160 System extends the functionality. Not only is the data automatically synchronized with other signals (ECG, fEMG, EDA, etc.,) but the recorded facial video can be monitored in the FaceReader display for real-time feedback.

Perhaps with a bit of practice, you can pull off that promotion and be able to afford that new car without tipping your hand!

For more information about FaceReader Software, watch the free On-Demand Webinar, “Using Facial Expressions to Understand Behavior” with BIOPAC CEO Frazer Findlay.

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.

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.

Stressing over the effects of stress

Several studies show chronic stress is typically detrimental to health, while acute stress may be linked to positive effects in addition to the negative counterparts

With April comes National Stress Awareness Month, and it bears noting that different types of stress have varying effects. Where chronic stress is typically detrimental to health, acute stress may be linked to positive effects in addition to the negative counterparts. But is this trade-off worth it?

In a biological psychology experiment testing the effect of oxytocin on acute social stress, researchers found different results between men and women. Subjects underwent several stress tasks while their electrocardiography and impedance cardiography were recorded with a BIOPAC MP Research System and amplifiers. The researchers found that after being given oxytocin during the stressful event, men had less negative affect and women had greater math performance (compared to the control group).

A neurobiology study examined the effect stress had on an extinction memory process when a competing association was paired with a previously aversive cue. To test this, participants were presented with two images, one that was paired with a shock from a BIOPAC bar electrode, and one that was not. Extinction memory training immediately followed this stimulus, with extinction retrieval testing following a day later. Data gathered by a BIOPAC data acquisition system suggested significantly lower retrieval in the group that experienced the acute stress stimulus.

Another biopsychology experiment measured the effect of acute stress on pro-inflammatory cytokine levels in the blood. BIOPAC equipment was used to measure ECG while participants were given the Trier Social Stress Test. After reviewing the data and blood samples, the researchers determined that levels of the cytokine cell, interleukin-1β, increased significantly immediately after the stress test.

The physiological and psychological impacts of stress are clearly multifaceted with many potential results. In some situations, a heightened positive affect or greater analytical thinking may be beneficial. But is this boost in mental performance worth the increase of inflammatory cells and lower memory retention? As with many aspects of life, moderation is the safest answer, ensuring the negative effects do not become chronic problems.

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

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.

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