Millisecond Precision

Create Reaction Time Tests Online

Build custom reaction time experiments for psychology and neuroscience research. Simple RT, choice RT, and complex paradigms with millisecond-precise timing.

Reaction Time Paradigms You Can Build

Simple Reaction Time

Respond as quickly as possible to any stimulus. Measures basic processing speed without decision-making.

Typical RT: 150-300ms

A/B

Choice Reaction Time

Discriminate between stimuli and respond accordingly. Measures decision speed and accuracy.

Typical RT: 300-500ms

Complex RT Tasks

Multi-step decisions, go/no-go, or conditional responses. Measures executive aspects of RT.

Typical RT: 400-800ms

Why Build RT Experiments with AssessKit?

Millisecond Timing

High-precision timing using requestAnimationFrame and performance.now().

No Coding Needed

Visual builder for all RT paradigms. Configure timing, stimuli, and responses.

Flexible Stimuli

Visual, auditory, or multimodal. Images, shapes, text, or custom media.

Rich Data Export

Trial-level data with timestamps, RT distributions, and summary statistics.

Technical Specifications

Timing Accuracy

  • Sub-millisecond timestamps

    Uses performance.now() for high-resolution timing

  • Frame-synced presentation

    requestAnimationFrame for consistent stimulus onset

  • Keyboard event timing

    Native event timestamps for accurate RT capture

Data Quality

  • Trial-level export

    Every trial with stimulus, response, and RT

  • Automatic outlier flagging

    Identifies anticipations and slow responses

  • Summary statistics

    Mean, median, SD, accuracy auto-calculated

Research Applications

Cognitive Psychology

Study attention, perception, and decision-making processes.

Clinical Assessment

Measure processing speed in ADHD, concussion, aging, and neurological conditions.

Sports Psychology

Assess athlete reaction time and decision speed under various conditions.

Human Factors

Evaluate operator performance, fatigue effects, and interface design.

Frequently Asked Questions

What is the difference between simple and choice reaction time?

Simple RT involves responding to a single stimulus with a single response (e.g., press spacebar when you see any stimulus). Choice RT requires discriminating between stimuli and selecting the appropriate response (e.g., press left for X, right for O). Choice RT is slower due to decision-making processes.

How accurate is online reaction time measurement?

AssessKit achieves millisecond-level precision using optimized JavaScript timing. While online testing adds some variability compared to lab settings, research shows online RT data is suitable for detecting experimental effects and individual differences.

What factors affect reaction time?

RT is influenced by: stimulus intensity, foreperiod duration, stimulus-response compatibility, practice effects, fatigue, age, and various clinical conditions. AssessKit lets you control all experimental parameters to isolate effects of interest.

Can I measure reaction time to images or sounds?

Yes. AssessKit supports visual stimuli (shapes, images, text), auditory stimuli, and multimodal presentations. You can create cross-modal RT experiments or standard visual/auditory RT tasks.

What outcome measures are provided?

AssessKit calculates: mean RT, median RT, RT standard deviation, accuracy, RT distributions, and trial-by-trial data. You can export raw data for custom analyses including ex-Gaussian fitting or drift diffusion modeling.

Ready to Build Reaction Time Experiments?

Create simple RT, choice RT, and complex paradigms. Free to start, no credit card required.

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