jsPsych

jsPsych enables precise control of stimulus presentation timing for web-based psychophysical experiments by synchronizing stimuli with the display refresh rate to minimize stimulus onset asynchrony (SOA) errors.

Key Features:

• Precise timing control: Controls display durations and stimulus onset asynchrony (SOA) with high temporal precision.
• Refresh-rate synchronization: Synchronizes stimulus presentation to the display device refresh rate.
• Supported stimulus types: Controls timing for geometric figures, images, sounds, and moving objects.
• Temporal precision measurements: Demonstrated deviations from intended SOAs of less than 10 milliseconds between two visual stimuli.
• Cross-platform variability reduction: Reduces variability in SOA measurements across different browser–computer combinations compared to conditions without the plugin.
• Audio–visual limitation: Shows larger variability of about 50 milliseconds for SOAs involving both visual and audio stimuli.

Scientific Applications:

• Visual psychophysics: Experiments requiring precise control of SOA and display durations for visual stimuli.
• Audio–visual timing studies: Investigations of synchrony and temporal integration between auditory and visual stimuli, noting increased variability for audio–visual SOAs.
• Cross-platform temporal assessment: Evaluation of temporal precision and variability across different browser–computer combinations in web-based experiments.
• Online behavioral experiments: Web-delivered psychophysical protocols where synchronization to display refresh rates is required for temporal accuracy.

Methodology:

Stimulus presentation is synchronized to the display refresh rate; evaluation measured deviations from intended SOAs across browser–computer combinations for visual–visual and visual–audio stimulus pairs, comparing plugin versus non-plugin conditions.