Inquisit: Behavioral Experiment Software Guide

Inquisit is a specialized behavioral research software platform developed by Millisecond Software for designing and administering computerized psychological experiments, cognitive assessments, and biometric reaction-time tasks. In cognitive science, social psychology, and clinical neuropsychology, measuring participant response latencies with sub-millisecond precision is essential for detecting subtle experimental effects. Inquisit provides an environment that bridges local laboratory testing with unmoderated remote online data collection, pairing standardized task scripts with dedicated desktop and mobile runtimes.

What it is used for in research

Researchers deploy Inquisit primarily for behavioral tasks where timing accuracy, trial randomization, and millisecond response measurement determine the validity of experimental outcomes. Common research applications include:

• Implicit cognition and bias: Administering the Implicit Association Test (IAT), Brief IAT (BIAT), and Go/No-Go Association Tasks to quantify automatic evaluative associations.
• Attentional control and executive function: Running classic cognitive paradigms such as the Stroop task, Flanker task, Simon task, and Continuous Performance Tasks (CPT).
• Neuropsychological and decision-making assessments: Measuring cognitive flexibility and risk propensity through standardized batteries like the Wisconsin Card Sorting Test (WCST), Iowa Gambling Task (IGT), and Balloon Analogue Risk Task (BART).
• Multi-modal biometric integration: Synchronizing behavioral trial events with physiological recording hardware (electroencephalography, functional near-infrared spectroscopy, and eye-tracking) using Lab Streaming Layer (LSL) markers.

Unlike general-purpose survey tools that rely on variable web browser timing, Inquisit captures exact display refresh intervals and hardware input events. Data generated from these paradigms frequently feed downstream inferential pipelines in tools such as jamovi or sample size verification in G-Power.

Install or access

Inquisit operates across two primary components: the authoring and laboratory administration suite (Inquisit Lab) and the participant deployment engine (Inquisit Web and Inquisit Player).

Inquisit Lab (Researcher Environment)

Inquisit Lab provides the integrated development environment (IDE) used to write, debug, and execute experiments on dedicated laboratory computers. Inquisit Lab is officially supported on:

• Windows: Windows 10 and Windows 11 (64-bit and 32-bit installations).
• macOS: macOS 12.4 and newer versions.

Researchers download Inquisit Lab directly from the official Millisecond Software download portal. The software provides an offline documentation viewer, syntax highlighting, and an integrated test-run environment.

Inquisit Web and Inquisit Player

For remote data collection, researchers host tasks on the Inquisit Web cloud infrastructure. Study participants do not need an Inquisit license; they access experiments via a web browser link that prompts the execution of the Inquisit Player:

• Desktop: Windows and macOS participant runtimes, installable as lightweight helper applications without administrative permissions.
• Mobile and tablet: Dedicated Inquisit Player applications available via the Apple App Store (iOS 14.0 or higher) and Google Play (Android 8.0 or higher).

The native Inquisit Player bypasses browser rendering engines and JavaScript garbage-collection pauses, executing the experimental code locally on the device to maintain millisecond timing fidelity.

Step-by-step task

The following numbered workflow outlines how to select, configure, and execute a standardized cognitive task from the Millisecond Test Library using Inquisit Lab:

1. Obtain the task script: Open Inquisit Lab and select File > Open to load an existing experimental script, or navigate to File > New Script to author a script. Validated paradigms (such as the Stroop or IAT) can be downloaded directly from the Millisecond Test Library in .iqx (Inquisit declarative script) or .iqjs (Inquisit 7 JavaScript) format.
2. Configure script parameters: Inspect the script in the code editor. Locate the <parameters> or <values> elements to customize study-specific variables, such as stimulus presentation durations, inter-trial intervals, block counts, or stimulus file paths.
3. Validate syntax: In the top navigation menu, click Experiment > Check Syntax (or press Ctrl+T on Windows / Cmd+T on macOS). Inquisit scans the file for undeclared stimuli, malformed element attributes, or broken branching logic. Address any syntax warnings listed in the Output pane.
4. Initialize execution: Select Experiment > Run (or press Ctrl+R on Windows / Cmd+R on macOS) to launch the experimental session in fullscreen mode.
5. Input session metadata: When the participant initialization dialog appears, enter the assigned Subject ID and Group ID. The Group ID determines condition counterbalancing defined in the script’s <expt> element.
6. Execute trials and verify completion: Run through the instruction screens and trial blocks. Upon reaching the final trial, Inquisit closes the presentation window and writes the resulting session data files to the designated data directory.

Output and how to read it

Inquisit generates plain-text, tab-delimited data files saved with the .iqdat file extension. By default, each completed administration produces two distinct output files:

1. Raw Trial-Level Data (*_raw.iqdat)

The raw data file records every individual trial presented during the session. Standard columns include:

• subject: The participant identifier entered at launch.
• group: The counterbalance group condition code.
• blockCode and blockNum: The name and sequential order of the active experimental block.
• trialCode and trialNum: The identifier and cumulative index of the specific trial.
• response: The participant input, recorded as a keyboard scancode, character string, or mouse button coordinate.
• correct: Accuracy scoring for the trial, formatted as a binary integer (1 = correct, 0 = incorrect or error).
• latency: Response time measured in milliseconds from the onset of the target stimulus to the registration of participant input.

2. Aggregated Summary Data (*_summary.iqdat)

The summary file produces a single row per participant session, condensing overall performance metrics:

• completed: Binary completion status (1 indicates the participant completed all blocks, 0 indicates early termination).
• propCorrect: Total proportion of correct responses across all eligible trials.
• meanRT: Average response latency computed exclusively across trials where correct == 1.

When preparing raw files for statistical analysis, researchers routinely filter rows to isolate valid trials (for instance, excluding trials where correct == 0 or where latency falls below 200 ms). Archiving raw .iqdat files alongside the exact script ensures computational reproducibility in institutional archives or public repositories such as the Open Science Framework (OSF).

Troubleshooting

When running lab-based or web-based studies, researchers commonly encounter four technical challenges:

• Display refresh rate synchronization errors: If Inquisit detects irregular display timings or missed vertical synchronization (V-Sync) pulses, it flags a timing discrepancy error. Verify that the host monitor uses a fixed refresh rate (such as 60 Hz or 120 Hz) and that variable refresh rate technologies (such as G-Sync or FreeSync) are disabled on the testing machine.
• Mobile device hardware permissions: If an Inquisit script requires microphone, camera, or touch-screen logging, mobile operating systems require explicit permission grants. Ensure that participant instruction sheets specify granting permissions when prompted by Inquisit Player on iOS or Android.
• Web session upload drops: If a remote participant experiences network disconnection during an Inquisit Web study, the Inquisit Player caches the completed session locally on their device and re-attempts the upload once connectivity resumes. Researchers can cross-reference participant IDs against session transaction logs in the Millisecond Web account.
• Lab Streaming Layer (LSL) marker drops: When interfacing with EEG or eye-tracking systems, verify that both the Inquisit workstation and the recording computer share a subnet and that local software firewalls permit UDP multicast communication on standard LSL ports.

Free alternatives

While Inquisit offers turnkey paradigms and unified cross-platform deployment, several open-source and free experimental platforms serve research laboratories with varying technical requirements:

Software	Primary Language	Web / Remote Testing	Timing Precision	Primary Research Use Case
Inquisit	Inquisit Script (.iqx), JavaScript (.iqjs)	Inquisit Web via native Inquisit Player apps	Sub-millisecond hardware-level timing	Standardized cognitive and social paradigms (IAT, Stroop) via Millisecond Test Library
PsychoPy	Python, JavaScript (PsychoJS)	Pavlovia platform integration	High precision via dedicated Python psychophysics libraries	Visual psychophysics, neuroscience paradigms, and complex custom sensory experiments
OpenSesame	Python, Graphical interface	OSWeb runtime	High precision on local desktop platforms	Classroom lab training, cognitive reaction time studies, and beginner-to-intermediate scripting
jsPsych	JavaScript	Native browser (Qualtrics, custom web servers)	Browser-dependent millisecond resolution	Web-first behavioral experiments and unmoderated crowdsourced participant studies
Lab.js	Visual builder, JavaScript	HTML5 export, native browser	Browser-dependent millisecond resolution	Online survey integration, behavioral tasks, and rapid visual experiment creation

Downstream analysis of data exported from these platforms often requires advanced structural or latent variable modeling in specialized statistical environments like Mplus or R packages.

FAQ

What is Inquisit Player 7?

Inquisit Player 7 is the dedicated native client application developed by Millisecond Software that executes Inquisit 7 web experiments on participant hardware. Available for Windows, macOS, iOS, and Android, it downloads experimental assets, locks presentation timing to native display clocks, captures precise input timestamps, and securely uploads completed trial data to the researcher’s cloud account.

What does inquisitive mean?

The word inquisitive is an English adjective meaning having or showing an eager desire to learn, inquire, or investigate. In everyday usage, it describes a curious personality or intellectual disposition. It is unrelated to Inquisit, which is a proprietary software platform named after psychological inquiry and behavioral data acquisition.

How do you spell Inquisit?

Inquisit is spelled I-N-Q-U-I-S-I-T, ending with the letter “t” and omitting any trailing “e”. Common misspellings include “Inquisite”, “Inquisitive”, or “Inquisiter”.

How much does Inquisitive cost?

Confusion often arises between Millisecond Inquisit and W.W. Norton’s “InQuizitive”. Norton’s InQuizitive is an adaptive educational quizzing tool paired with college textbooks, which requires a student access code or individual purchase through the publisher. In contrast, Millisecond Inquisit is a behavioral research platform licensed to academic institutions, departments, and laboratory investigators on an annual or perpetual workstation basis. For participants taking studies, the Inquisit Player client is completely free.

What data formats does Inquisit export?

Inquisit exports tabular plain-text files using the .iqdat file extension, which can be formatted as tab-delimited or comma-separated values. These files import directly into statistical packages including R, SPSS, Stata, and Python pandas without requiring proprietary conversion utilities.

Sources

• Millisecond Software. (2026). Inquisit 7 User Manual and Language Reference. Millisecond Software LLC. https://www.millisecond.com/support/docs/v7/html/inquisit.htm
• Millisecond Software. (2026). Inquisit Downloads and System Requirements. Millisecond Software LLC. https://www.millisecond.com/download
• Millisecond Software. (2026). Millisecond Psychological Test Library. Millisecond Software LLC. https://www.millisecond.com/testlibrary
• University of Michigan. (2026). Inquisit Software Directory Listing. U-M Information and Technology Services. https://software.umich.edu/directory