Chris Jackson, Author at BIOPAC Blog

Hitting the Mark: Using Event Markers to Improve Data Quality

Life is a series of events—some are planned while others catch us completely by surprise. This holds true in the lab where the quality of experiments and data depend on accurately identifying, tracking, and sorting key events as they occur. Events like the introduction of stimuli and a test subject’s reaction directly impact data.

In this context, we define an “event” as piece of information associated with a specific time in a waveform. An event can capture points of interest within a file (e.g., subject moved, dose added) or on a particular channel (e.g., T-wave onset).

Whether intentional or not, critical events need to be easily located and identified by those running an experiment. Event marking provides the key to this by helping researchers eliminate outlier data while making it possible to locate data that is significant to the experiment. Today’s researchers benefit from data acquisition software that offers some form of event marking functionality to easily identify, label, and categorize such events. BIOPAC’s latest build of AcqKnowledge, for example, integrates extremely easy-to-use event marking tools that enable users to mark “quick events” with a simple tap of a function/hotkey for 17 different event categories, each containing multiple types of events.

“I’m struggling to think of any time you wouldn’t be using these,” said BIOPAC Technical Support Manager David Pollock as part of the recent webinar AcqKnowledge Bootcamp: Set Up Experiments to Facilitate Data Analysis. “They are critical to being able to interpret your data after you acquire it.”

The benefits of event markers include:

Allowing researchers to differentiate stages of an experiment
Making it easy to eliminate outlier data
Allowing researchers to track and identify stimuli
Providing control over event tracking, thus eliminating errors

A Tale of Two Studies

A pair of recent studies illustrate how data acquisition software like AcqKnowledge can streamline event marking. The first sought to test the viability of various commercial-off-the-shelf ECG sensors for monitoring stress levels in participants. Test participants used a manual button to self-mark stress events triggered by mental arithmetic tasks, startle response tests, and a cold-water response test. A BIOPAC MP Research System data acquisition unit provided a clinical baseline for comparison with the pair of COTS ECG monitors. The limitations of self-reported events were revealed when participants were found to have accidentally activated the stress “clicker” about 60% of the time.

A similar 2018 John Hopkins University study avoided this problem through both automated and researcher-controlled event marking. When examining how military commanders maintain combat effectiveness while responding to a range of potentially stressful battlefield situations, researchers employed AcqKnowledge to record event marks at the onset and offset of various stimuli. Physiological data was fed to an AcqKnowledge-equipped computer via a BIOPAC DAQ connected to an STP100C digital interface module. Event markers generated by both AcqKnowledge and E-Prime allowed researchers to easily identify stimuli as well as each task the participants performed by name, start time, end time, and duration.

Not leveraging the power of event marking tools can result in key experimental events being lost in a flood of data, potentially corrupting results. Check out this video tutorial to learn more about event marking with AcqKnowledge.

Enhance Consistency with an Automated Lab Refresh

The global COVID-19 pandemic made in-person lab work impossible under many circumstances and difficult in the best of conditions. Now, as researchers and students begin to return to the lab, an opportunity presents itself for a fresh start. One way in which labs are refreshing their approach to research and education is by adding software and equipment that allows for the automation of procedures and analysis with the goal of increasing repeatability and reproducibility within experiments and research.

It’s been a challenging 18 months for science educators and those running research facilities. The global COVID-19 pandemic made in-person lab work impossible under many circumstances and difficult in the best of conditions. Now, as researchers and students begin to return to the lab, an opportunity presents itself for a fresh start. One way in which labs are refreshing their approach to research and education is by adding software and equipment that allows for the automation of procedures and analysis with the goal of increasing repeatability and reproducibility within experiments and research.

Crisis of reproducibility

The phrases “reproducibility crisis” and “replication crisis” became buzzwords in the scientific community in the 2010s, with that notoriety spilling over into both the scientific and mainstream media’s coverage of the sciences. Several high-profile scientific and sociological studies were called into question when researchers were unable to reproduce their results. In 2015, a group of psychology researchers under the moniker of the “Open Science Collaboration” found that they were only able to reproduce the findings of 68% of studies published in high-ranking peer-reviewed journals. A 2016 survey of 1,576 researchers by the journal Nature similarly found that 52% agreed that there was a “crisis” of reproducibility, though most said they still trusted published research.

The automated advantage

One step that researchers can take to ensure the reproducibility of their experiments and thereby boost the integrity of their data and conclusions is by automating procedures, workflow, and record keeping. These steps not only reduce the possibility for human error, but also provide a clear roadmap for future researchers to repeat processes in the lab to review and test results. The National Academies of Sciences, Engineering, and Medicine guide Reproducibility and Replicability in Science (National Academies Press, 2019) outlines several of the ways in which automation is being used to enhance reproducibility of research results, including record keeping, data analysis, data version control, and workflow management. The publication notes that “automated scientific workflows are essential in data-intensive and large-scale science missions that aim to be computationally reproducible.”

A 2019 study by researchers at the Indiana University School of Informatics, Computing, and Engineering employed these techniques to demonstrate “how automation can be used to address many of these factors contributing to the replication crisis.” The study focused on the controlled rearing of chicks, comparing automated and non-automated research methods. The study found that the automated tracking system allowed researchers to increase the amount of data collected from each test subject, which in turn “reduced measurement error by 60% and increased the effective size of experiments by about 300%.”

An automated refresh

BIOPAC’s AcqKnowledge data acquisition and analysis software allows labs of any size to gain the advantage of automation to improve both the efficiency and effectiveness of research. Features like Batch Processing and BIOPAC Basic Scripting help eliminate the potential for human error by consolidating multiple tasks into a single automated routine. A heightened level of standardization and consistency results in improved data quality. Adding a Basic Scripting license to AcqKnowledge 5.0.6 ensures results are reproducible regardless of who is carrying out the experiment.

The Right Tools: Streamlining Stimulus Presentation

Our nervous system processes information from a dizzying array of stimuli—visual, auditory, thermal, olfactory, and tactile, among others. How organisms respond to stimuli provides researchers with a wealth of information on how they adapt, learn, and live. The complex interaction between stimulus and response presents a myriad of challenges when it comes to creating effective stimuli in the research environment and accurately gathering data from subjects.

Today’s researchers have been gifted with a variety of stimulus presentation options to suit their individual needs. Complex experiments may call for robust solutions that integrate a wide range of stimulus presentation and data acquisition hardware and software, often from various industry leading manufacturers such as BIOPAC, E-Prime, and Cedrus. Such experiments can combine multiple stimuli with advanced stimulus controls and data gathering techniques.

Stimulus presentation, however, is not a one-size-fits-all proposition and some researchers may prefer a simpler solution that integrates visual stimulation presentation tools with powerful eye-tracking, as is available with BIOPAC’s screen-based Eye Tracking system. Additionally, AcqKnowledge now offers native integration and synchronization of stimulus presentation, eye tracking, and physiology data acquisition and analysis, all easily managed from a single application.

The seamless integration of stimulus presentation in data gathering and analysis allowed a team of researchers from the University of Connecticut and Emory University to monitor electrodermal activity (EDA) in subjects as they responded to pain stimuli induced by electrothermal grills. The goal of the study was to determine the viability of using such grills to induce pain without causing physical harm to research subjects. Researchers recorded and stored EDA signals from electrodes attached to the subjects’ fingers with a BioNomadix® wireless amplifier and MP160 data acquisition device connected to a computer running AcqKnowledge. A STMISOC programmable stimulus isolation adapter provided EP stimulation, allowing software-controlled adjustment of stimulus pulse width, repetition, and setup of an arbitrary pulse stimulus sequence via AcqKnowledge.

Using a single integrated system doesn’t necessarily equate sacrificing utility, nor does cross-platform integration need to be complicated. A group of researchers in Beijing recently explored the connection between fear response, conditioning, and memory that required the application of electrical shocks of varying intensity. A constant current STM200 stimulator delivered the shocks, in this case controlled by E-Prime software while data was collected by an MP150 running AcqKnowledge. In its current build, AcqKnowledge also integrates stimulus presentation and data acquisition, potentially streamlining the design of such an experiment.

Studies requiring the simultaneous introduction of multiple stimuli can raise the level of complexity for researchers, as it did in a recent study that examined a link between pleasant touch and scent with facial muscle activity and heart rate. Facial EMG and ECG data were collected using a BIOPAC MP Research System with a BioNomadix® wireless system connected to a computer running AcqKnowledge; current builds of the software provide full integration of scent delivery hardware.

BIOPAC’s new integrated stimulus presentation meshes seamlessly with Eye Tracking and data acquisition, providing researchers with an integrated solution to save valuable time and effort.

BIOPAC Systems, Inc. provides life science researchers and educators with data acquisition and analysis systems that inspire people and enable greater discovery about life.

Scaling Up: The Challenges of Large-Group Studies

When formulating an approach to a research study, planning experiments, and choosing the right technology for the job, size matters. Research studies with human subjects generally fall into three scale-related categories: individual, small-group, and large-group studies. When we discuss “size” in this context, we are talking about the number of subjects sampled together at one time and in one location.

Single-participant studies sample data from subjects separately while dyadic research gathers input from two subjects at the same time and place. It may be necessary, however, to take readings from three, four, or dozens of study subject simultaneously. In such cases, researchers often want to measure how the participants react to identical stimuli or the same external conditions such as those found in a classroom, courtroom, or theater setting. Researchers may also seek to measure how subjects react or interact with other members of the study group such as during business exchanges, in a meeting room environment, or in game sessions or other competitive settings.

These large-group studies present critical challenges that may not normally occur in single-participant studies. First, the stimuli to which the participants respond must be presented in a uniform and synchronous manner. Whether the stimuli are visual or auditory, thermal or olfactory, electrical or haptic, all study subjects must be able to respond to the same stimulus.

A recent study in behavioral economics measured psychophysiological reactions to various stimuli in the form of market and trading games in which multiple interactions took place between a set of “players.” Timing was critical to accurately measure the participants’ physiological responses to trades, losses, and gains. Both the presentation of stimuli and the recording of the participants’ reactions had to be precisely synchronized.

Methods for recording subjects’ response may include biopotential data such as ECG/EKG, EEG, EMG; transducer signals that can include electrodermal activity (EDA), respiration, and temperature; eye tracking; video recording; subjective response; or fNIRS, to name just a few examples. In the above study, participants were equipped with a photodiode that recorded responses during a decision-making experiment. Signals from the photodiodes were transmitted to a 16-channel BIOPAC MP150 Data Acquisition System (since replaced by the MP160 Data Acquisition System), allowing the simultaneous, synchronous recording of timing data from up to 16 subjects.

Synchronizing data is just one consideration when conducting multi-participant studies. Other logistical challenges arise when participants must interact with their surroundings. Another large-group study compared physical and psychological activity among seven-year-old elementary school children as they learned geometry through movement-based teaching methods. This presented several challenges, including the age of the subjects and the need for freedom of movement. Such problems are common to large-group studies that require multiple participants to move unimpeded by recording apparatuses. Typically, a researcher will choose between either a minimally invasive tethered device that can be wired to a data acquisition unit (e.g., BIOPAC ECG100D Smart Amplifier) or a wireless device (e.g., BIOPAC BN-ECG2 Wireless ECG Amplifier) that permits additional freedom of movement. In this study, the researchers used wearable devices to record the children’s energy expenditure, intensity of movements, EDA, body heat flux, and skin temperature.

While large-group studies present an array of unique challenges to gathering data, these challenges can be overcome through careful planning and by choosing the right tools for the job. BIOPAC offers a wide range of scalable technologies, software, and accessories for conducting research with individual subjects, pairs, or large groups that can be adapted to an array of scenarios and research settings.