Psychophysiological analysis (PSPHA): A modular script based program for analyzing psychophysiological data

This 2006 paper introduces PSPHA (Psychophysiological Analysis), a free modular script-based software program for analyzing psychophysiological data in the time domain. Developed at Ghent University, PSPHA provides interactive analysis modules for skin conductance, heart rate, respiration, and startle responses with capabilities for synchronization, filtering, and artifact detection.

Software development paper describing a Visual Basic 6/VBScript-based modular analysis program with specialized modules for different physiological signals, FIR filtering capabilities, and wizard-based parameter adjustment.

Background & Context

Prior to 2006, psychophysiological researchers faced a significant methodological bottleneck. Complex tailor-made and interactive analyses of biosignals and synchronization between experimental stimuli and psychophysiological responses were often required, yet available software solutions were typically proprietary, expensive, or limited to specific hardware platforms. This created barriers to reproducibility and collaborative research, particularly for laboratories with limited budgets or those working across different acquisition systems.

The need was especially acute for researchers studying deception detection, fear conditioning, startle responses, and emotional processing—all of which required precise time-locking of physiological measures to experimental events. Existing programs often lacked standardized approaches, didn't allow synchronization between stimuli and responses, or couldn't improve signal-to-noise ratios through filtering and data reduction. This paper introduced PSPHA as a free, open-access solution to address these limitations.

Research Design & Methodology

This is a software development and validation paper rather than an empirical study. The development team from the Department of Applied Mathematics and Computer Science at Ghent University, Belgium, created PSPHA with several key design principles in mind.

The program was written in Visual Basic 6 and VBScript, an internationally accepted computer language, to maximize accessibility and allow users to modify scripts for particular applications. The architecture features:

• Modular design: A modular script-based program for analyzing biosignals in the time domain, with modules that can be integrated in VBScript
• Signal processing capabilities: FIR (finite impulse response) filtering for EMG signals, smoothing, and maxima/minima detection
• Multi-channel analysis: Data displayed on screen with zoom and pan capabilities, allowing all or selected channels to be analyzed
• User-friendly interface: A wizard that allows easy adaptation of parameters

Results & Key Findings

PSPHA successfully provides comprehensive analysis modules for multiple physiological signals. The software includes specialized modules for skin conductance, heart rate, respiration, and startle eyeblink responses.

For skin conductance analysis, researchers using PSPHA have successfully extracted responses by calculating amplitude differences between baseline and peak values within specified time windows. For respiration analysis, PSPHA calculates respiratory amplitude (depth of breathing) and respiratory period (duration of breathing).

The heart rate module demonstrates sophisticated ECG processing: Heart rate data are analyzed in the time domain without smoothing, because hardware band pass filters (8-40 Hz) are typically used in amplifiers; PSPHA detects the highest maxima (R-peak) in the ECG signal, with only maxima followed by a minimum considered valid.

Key technical achievements include:

• Free and accessible: A free, interactive, and flexible program available to the research community
• Widespread adoption: Multiple published studies confirm successful use for startle blink EMG, skin conductance responses, and fear conditioning research
• Artifact detection: Visual inspection capabilities allow technical abnormalities and artifacts to be eliminated

Discussion & Significance

PSPHA represented a significant democratization of psychophysiological data analysis. By providing free, flexible software written in an accessible programming language, the developers lowered barriers to entry for laboratories worldwide. The modular architecture proved particularly valuable, allowing researchers to customize analyses for specific experimental paradigms without starting from scratch.

The software's impact is evidenced by its sustained use in polygraph-relevant research. Studies of the Concealed Information Test, startle response modulation during deception, and fear conditioning—all critical to understanding the psychophysiological basis of polygraph testing—have successfully employed PSPHA for data processing. The software has been cited and used for psychophysiological analysis in behavioral research, demonstrating its reliability and utility beyond the initial development team.

For the polygraph field specifically, PSPHA's contribution lies in providing standardized, reproducible methods for analyzing the same physiological channels used in polygraph testing: electrodermal activity, cardiovascular responses, and respiration. This facilitates translation between laboratory research and field applications.

Limitations & Considerations

Frequency analysis (e.g., Fast Fourier Transform) was not implemented in the initial version, limiting analyses to the time domain. This restricts certain types of heart rate variability and spectral analyses that have become increasingly important in psychophysiology.

The software relies on Visual Basic 6 and VBScript, which while widely compatible at the time of publication, may present compatibility challenges with modern operating systems and 64-bit architectures. Data format requirements also necessitate conversion to delimited formats, adding preprocessing steps for some users.

As a tool paper rather than a validation study, the publication doesn't provide formal reliability or validity statistics comparing PSPHA output to established commercial software or gold-standard manual scoring methods.

Practical Applications

For polygraph researchers and practitioners, PSPHA offers a cost-free alternative for offline analysis of electrodermal, cardiovascular, and respiratory data collected during laboratory studies. Its particular strength lies in analyzing data from mock crime scenarios or Concealed Information Tests where precise time-locking to question presentation is critical. The software's ability to handle artifact detection and visual inspection makes it suitable for quality control in research settings.

The modular, script-based approach allows polygraph researchers to develop standardized analysis protocols that can be shared across laboratories, enhancing reproducibility. However, PSPHA is best suited as a research tool rather than a replacement for validated commercial polygraph scoring algorithms used in field practice. Its value lies primarily in advancing our scientific understanding of the psychophysiological responses underlying polygraph testing.