Accuracy test conducted in April 2022.

Summary

I programmed to present two white rectangles for 500 ms / 30 frames and 50 ms / 3 frames and an audio file for 100 ms, and measured actual durations for these stimuli using the Black Box Toolkit. The programs were made using jsPsych and the psychophysics plugin. The presentation time for visual stimuli was specified in terms of milliseconds or frames. The audio file was pre-created to have a length of 100 ms.

The latest psychophysics plugin has Pixi mode in which visual stimuli are presented using PixiJS functionality. I compared Pixi mode and non Pixi mode.

The results showed that:

• There was no difference between Pixi and non Pixi mode and that accuracy and precision of both modes were sufficiently high.
• The precision seemed to be slightly better when the time was specified in terms of frames than was specified in terms of milliseconds.
• It has been reported that it is difficult to present the visual and audio stimuli at intended SOAs, and the issue remains at this time.
• In Pixi mode of Firefox some visual stimuli were presented for a shorter time than expected or did not actually appear on the screen. We should be cautious about conducting online experiments using Firefox.

Programs

You can run the programs I used in this accuracy test.

Apparatus

• Windows laptop PC (hp ProBook 430 G3, Intel Core i5-6200U CPU 2.3GHz 2.40GHz 64bit 8GB)
• The Black Box Toolkit
• Chrome 100.0.4896.127
• Firefox 99.0.1
• Edge 100.0.1185.44

The histograms below are based on 100 trials.

Actual display duration of a visual stimulus which was intended to be presented for 500ms/30frames.

Chrome

Non Pixi mode in frames

##   [1] 497.75 498.00 498.00 498.00 498.00 498.25 498.00 498.00 498.00 498.00
##  [11] 498.00 498.00 498.00 498.00 497.75 498.00 498.25 498.25 498.25 498.25
##  [21] 498.00 498.00 498.00 498.00 498.00 498.00 498.00 498.00 498.00 498.25
##  [31] 498.00 498.00 498.25 498.00 497.75 498.00 497.75 498.00 497.75 497.75
##  [41] 497.75 498.00 498.00 498.00 498.00 498.00 498.00 498.00 498.00 498.00
##  [51] 498.00 498.00 498.00 498.00 498.00 498.00 498.00 498.00 498.00 498.00
##  [61] 498.00 498.25 498.00 498.00 498.00 498.00 498.25 498.00 498.00 498.00
##  [71] 498.00 498.00 498.00 498.25 498.00 498.00 498.00 497.75 498.00 498.00
##  [81] 498.00 498.00 498.00 498.00 498.00 498.25 498.25 497.75 497.75 498.00
##  [91] 497.75 498.00 498.00 498.00 498.25 497.75 498.00 498.00 498.00 498.00

Pixi mode in frames

##   [1] 498.00 498.00 498.25 498.25 498.00 498.00 498.00 497.75 498.00 498.00
##  [11] 498.00 498.00 497.75 498.00 498.00 497.75 497.75 498.00 498.00 498.00
##  [21] 498.00 498.25 498.00 498.00 498.00 498.00 498.00 498.00 498.00 498.00
##  [31] 498.00 498.00 497.75 498.00 497.75 498.00 498.00 498.00 498.00 498.00
##  [41] 498.00 498.00 498.00 497.75 498.00 498.00 498.00 498.00 498.00 498.00
##  [51] 498.00 498.00 498.00 498.00 498.00 498.00 498.00 497.75 498.00 498.25
##  [61] 498.25 498.00 498.00 498.00 498.25 498.00 498.00 498.00 498.00 497.75
##  [71] 514.50 498.00 497.75 498.00 498.00 498.00 498.25 498.00 498.00 497.75
##  [81] 498.00 498.00 498.00 498.00 498.00 498.00 498.00 498.00 498.25 498.00
##  [91] 498.00 498.00 498.00 498.00 498.00 498.00 498.00 498.00 498.00 498.00

Non Pixi mode in ms

##   [1] 498.00 498.00 498.00 497.75 497.75 498.00 498.00 514.75 498.00 498.00
##  [11] 498.00 498.00 498.25 497.75 498.00 498.00 498.00 497.75 498.00 498.00
##  [21] 498.00 498.00 498.00 498.00 498.00 514.75 514.75 514.75 514.75 514.50
##  [31] 497.75 497.75 498.00 498.00 514.50 514.50 498.00 514.50 498.00 498.00
##  [41] 498.00 498.00 514.75 498.00 514.75 498.00 498.00 514.50 498.00 498.00
##  [51] 498.00 514.75 498.00 514.50 514.75 514.75 514.75 514.75 498.00 498.00
##  [61] 498.00 498.00 498.00 498.00 498.00 498.00 498.00 498.25 498.00 498.00
##  [71] 498.00 498.00 498.00 498.00 498.00 498.25 498.00 498.00 498.00 498.00
##  [81] 498.00 498.00 498.00 514.75 498.00 498.25 498.00 498.25 498.25 498.00
##  [91] 498.25 498.00 498.00 498.00 498.00 498.00 498.00 498.00 498.00 498.00

Pixi mode in ms

##   [1] 514.50 498.00 498.00 498.00 498.25 498.00 498.25 498.00 498.25 498.00
##  [11] 498.25 514.75 498.25 498.25 498.25 498.25 498.25 498.25 498.25 498.00
##  [21] 498.25 498.00 498.00 498.00 498.00 498.00 498.00 498.00 498.00 498.25
##  [31] 498.00 498.00 498.00 498.00 498.25 498.25 498.00 514.75 498.00 498.00
##  [41] 498.00 497.75 498.00 498.00 498.00 498.25 498.00 498.00 498.00 498.00
##  [51] 498.00 498.00 498.00 498.00 498.00 498.00 498.00 498.00 498.00 498.00
##  [61] 498.00 498.00 498.00 498.00 498.00 498.00 498.00 498.00 498.00 498.00
##  [71] 498.00 514.75 498.00 498.00 498.00 498.00 514.75 498.00 498.00 498.00
##  [81] 498.00 498.00 498.00 514.75 497.75 498.00 498.00 498.00 498.00 514.50
##  [91] 498.00 498.00 498.00 498.00 498.00 498.00 498.00 498.00 498.00 498.00

Firefox

Non Pixi mode in frames

##   [1] 497.75 498.00 498.00 498.00 498.00 498.00 497.75 498.00 498.00 498.00
##  [11] 497.75 498.00 498.00 498.00 498.00 498.00 498.00 498.00 498.00 498.00
##  [21] 497.75 498.00 498.00 498.00 498.00 514.50 498.00 498.00 498.00 498.00
##  [31] 498.00 497.75 498.00 498.00 498.00 498.00 498.00 498.00 498.00 498.00
##  [41] 498.00 497.75 497.75 497.75 498.00 498.00 498.00 497.75 497.75 498.00
##  [51] 498.00 498.00 498.00 497.75 497.75 498.00 498.00 498.00 498.00 498.00
##  [61] 498.00 498.00 498.00 498.00 498.00 498.00 498.00 514.75 497.75 498.00
##  [71] 498.00 498.00 498.00 498.00 498.00 498.00 498.00 498.00 497.75 498.00
##  [81] 498.00 498.00 498.00 498.00 498.00 498.00 498.00 498.00 498.00 498.00
##  [91] 498.00 514.50 498.00 498.00 498.00 498.00 498.00 498.25 498.00 498.00

Pixi mode in frames

##   [1] 498.00 531.50 498.00 498.00 498.00 497.75 498.00 498.00 498.00 497.75
##  [11] 498.00 498.00 498.00 497.75 498.00 498.00 498.00 498.25 498.25 498.00
##  [21] 514.75 498.00 498.00 514.75 497.75 498.00 514.75 498.25 498.00 498.25
##  [31] 498.00 498.00 498.00 498.00 514.50 497.75 497.75 498.00 498.00 497.75
##  [41] 498.00 498.00 498.00 498.25 498.00 498.00 497.75 498.00 498.00 498.00
##  [51] 498.25 514.50 498.25 498.00 498.00 498.00 497.75 498.00 498.00 498.00
##  [61] 498.00 531.25 498.00 498.00 498.25 498.00 498.00 498.00 498.25 548.00
##  [71] 498.00 498.25 498.00 514.75 498.00 498.25 498.25 498.00 498.00 548.25
##  [81] 514.50 448.25 498.00 498.00 498.00 498.00 498.00 498.00 498.00 498.00
##  [91] 498.00 498.00 498.00 498.00 498.25 498.00 514.75 498.00 498.00 498.00

Non Pixi mode in ms

##   [1] 498.00 498.00 498.00 498.00 498.00 498.00 498.00 497.75 498.00 498.00
##  [11] 498.00 498.00 498.00 498.00 498.00 498.00 498.00 498.00 498.00 498.00
##  [21] 498.00 498.00 498.00 498.00 498.00 498.00 498.00 498.00 498.00 497.75
##  [31] 498.00 498.00 498.00 498.00 498.00 498.00 498.00 498.00 497.75 498.00
##  [41] 498.00 498.00 498.00 497.75 498.00 498.00 498.00 498.00 498.00 498.00
##  [51] 498.00 497.75 498.00 498.00 498.00 498.00 498.00 498.00 498.00 498.00
##  [61] 498.00 498.00 498.00 498.00 498.00 498.00 498.00 498.00 498.00 498.00
##  [71] 498.25 498.00 498.00 498.00 498.00 498.00 498.00 498.00 498.00 498.25
##  [81] 498.00 498.00 497.75 497.75 498.00 498.00 497.75 498.00 498.00 498.00
##  [91] 498.00 498.00 498.00 498.00 481.50 498.25 498.25 498.00 498.00 498.25

Pixi mode in ms

##   [1] 448.00 414.75 414.75 398.00 398.25 415.00 414.75 431.50 415.00 414.75
##  [11] 414.50 414.50 414.75 414.75 414.75 414.75 414.75 414.75 414.75 414.75
##  [21] 414.75 414.75 448.00 431.25 414.75 414.75 448.00 414.75 398.00 414.75
##  [31] 414.75 381.25 414.75 414.75 398.00 448.00 414.50 414.75 414.75 414.75
##  [41] 414.75 381.50 414.75 414.75 398.00 414.50 414.50 414.50 414.75 447.75
##  [51] 414.75 414.50 414.75 414.75 431.25 414.50 414.75 398.00 414.75 414.50
##  [61] 414.75 414.75 414.50 398.00 414.75 414.75 398.00 414.75 514.75 398.00
##  [71] 398.00 398.00 414.75 448.00 448.00 448.00 431.50 414.75 414.75 414.75
##  [81] 414.75 414.75 431.50 414.75 414.75 414.75 431.25 398.25 414.75 414.75
##  [91] 431.75 448.00 398.00 381.50 414.75 414.50 415.00 414.75 414.75 414.75

Edge

Non Pixi mode in frames

##   [1] 498.00 498.00 498.00 498.00 497.75 497.75 497.75 497.75 497.75 497.75
##  [11] 498.00 498.00 497.75 498.00 498.00 497.50 497.75 498.00 498.00 498.00
##  [21] 497.75 497.75 497.75 498.00 497.75 498.00 498.00 498.00 497.75 498.00
##  [31] 497.75 497.75 497.75 497.75 498.00 498.00 498.00 498.00 497.75 497.75
##  [41] 497.75 497.75 497.75 497.75 497.75 497.75 497.75 498.00 498.00 498.00
##  [51] 498.25 498.00 498.00 498.00 498.00 497.75 498.00 498.00 498.00 498.00
##  [61] 498.00 497.75 497.75 497.50 498.00 497.75 497.75 497.75 497.75 497.75
##  [71] 497.75 497.75 497.75 498.00 498.00 498.00 498.00 498.00 498.00 497.75
##  [81] 498.00 498.00 497.75 497.75 497.75 498.00 497.75 497.75 497.75 497.75
##  [91] 497.75 497.75 497.75 497.75 498.00 497.75 497.75 497.75 498.00 497.75

Pixi mode in frames

##   [1] 498.00 498.00 498.00 498.00 497.75 497.75 497.75 498.00 497.75 497.75
##  [11] 497.75 497.75 497.75 497.75 497.75 498.00 497.75 498.00 497.75 498.00
##  [21] 497.75 497.75 514.50 497.75 498.00 497.75 498.00 497.75 497.75 497.75
##  [31] 497.75 497.75 498.00 497.75 497.75 497.75 497.75 498.00 497.75 497.75
##  [41] 498.00 497.75 498.00 497.75 498.25 497.75 498.00 498.00 497.75 497.75
##  [51] 497.75 497.75 497.75 497.75 514.50 497.75 498.00 497.75 498.00 497.75
##  [61] 497.75 497.75 497.75 497.75 498.00 497.75 498.00 498.00 498.00 498.00
##  [71] 498.00 497.75 498.00 498.00 497.75 498.00 497.75 497.75 498.00 497.75
##  [81] 498.00 497.75 497.75 498.00 498.00 497.75 497.75 497.75 498.00 498.00
##  [91] 498.00 497.75 497.75 497.75 497.75 497.75 498.00 498.00 498.00 497.75

Non Pixi mode in ms

##   [1] 514.50 497.75 498.00 497.75 514.50 497.75 497.75 497.75 497.75 497.75
##  [11] 497.75 497.75 498.00 498.00 498.00 514.50 497.75 497.75 497.75 514.50
##  [21] 497.75 497.75 497.75 497.75 497.75 497.75 498.00 497.75 514.50 497.75
##  [31] 497.75 514.25 497.75 497.75 497.75 497.75 514.50 497.75 497.75 514.50
##  [41] 497.75 514.50 497.75 498.00 497.75 497.75 497.75 497.75 497.75 514.75
##  [51] 498.00 514.50 498.00 498.00 498.00 514.50 514.75 497.75 514.75 497.75
##  [61] 498.00 498.00 514.75 514.75 514.50 497.75 514.25 497.75 514.25 497.75
##  [71] 498.00 497.75 498.00 514.50 514.50 514.50 497.75 514.50 498.00 497.75
##  [81] 514.50 498.00 514.50 497.75 514.50 497.75 514.25 514.50 514.50 497.75
##  [91] 514.50 497.75 498.00 498.00 498.00 514.50 498.25 497.75 514.25 497.75

Pixi mode in ms

##   [1] 497.75 514.50 498.00 497.75 498.00 498.00 498.00 498.00 497.75 497.75
##  [11] 498.00 498.00 498.00 497.75 497.75 497.75 498.25 497.75 497.75 497.75
##  [21] 497.75 497.75 497.75 497.75 497.75 498.00 514.25 497.75 497.75 497.75
##  [31] 497.75 497.75 497.50 497.75 497.75 497.75 464.50 498.00 498.00 498.00
##  [41] 498.00 498.00 497.75 497.75 497.75 497.75 498.00 497.75 498.00 497.75
##  [51] 497.75 498.00 514.50 497.75 497.75 498.00 497.75 497.75 514.50 497.75
##  [61] 497.75 498.00 497.75 498.00 497.75 498.00 497.75 497.75 514.50 497.75
##  [71] 497.75 497.75 514.50 498.00 514.50 497.75 514.50 497.75 497.75 498.00
##  [81] 497.75 481.25 497.75 498.00 497.75 497.75 497.75 514.50 497.75 498.00
##  [91] 497.75 497.75 497.75 497.75 497.75 497.75 498.00 497.75 481.00 497.75

Actual display duration of a visual stimulus which was intended to be presented for 50ms/3frames.

Chrome

Non Pixi mode in frames

##   [1] 47.25 47.50 47.50 47.50 47.50 47.25 47.25 47.25 47.50 47.50 47.50 47.50
##  [13] 47.25 47.25 47.50 47.50 47.25 47.50 47.50 47.25 47.25 47.50 47.25 47.50
##  [25] 47.50 47.50 47.75 47.50 47.25 47.50 47.50 47.25 47.25 47.50 47.50 47.50
##  [37] 47.50 47.25 47.25 47.25 47.50 47.25 47.25 47.50 47.25 47.25 47.25 47.50
##  [49] 47.50 47.25 47.50 47.25 47.25 47.25 47.25 47.50 47.50 47.25 47.50 47.50
##  [61] 47.75 47.25 47.50 47.50 47.50 47.50 47.50 47.25 47.50 47.50 47.50 47.50
##  [73] 47.50 47.50 47.50 47.25 47.25 47.25 47.50 47.75 47.50 47.50 47.50 47.50
##  [85] 47.00 47.25 47.50 47.25 47.50 47.25 47.50 47.50 47.50 47.50 47.50 47.50
##  [97] 47.50 47.50 47.25 47.50

Pixi mode in frames

##   [1] 47.25 47.50 47.25 47.25 47.50 47.25 47.25 47.25 47.25 47.25 47.50 47.50
##  [13] 47.50 47.25 47.25 47.25 47.50 47.25 47.25 47.25 47.50 47.50 47.25 47.50
##  [25] 47.50 47.50 47.50 47.50 47.50 47.50 47.25 47.50 47.50 47.25 47.50 47.50
##  [37] 47.50 47.50 47.50 47.00 47.25 47.50 47.25 47.50 47.25 47.50 47.50 47.50
##  [49] 47.50 47.50 47.75 47.25 47.25 47.50 47.50 47.50 47.50 47.50 47.50 47.25
##  [61] 47.25 47.50 47.50 47.50 47.50 47.50 47.50 47.50 47.25 47.50 47.50 47.50
##  [73] 47.50 47.25 47.50 47.50 47.25 47.50 47.50 47.50 47.50 47.50 47.50 47.50
##  [85] 47.50 47.50 47.75 47.25 47.50 47.50 47.50 47.75 47.50 47.50 47.25 47.50
##  [97] 47.50 47.25 47.50 47.50

Non Pixi mode in ms

##   [1] 47.25 47.50 47.25 47.50 47.50 47.50 47.50 47.50 47.50 47.25 47.50 47.25
##  [13] 47.75 47.75 47.50 47.50 47.50 47.50 47.50 47.50 47.50 47.50 64.00 47.75
##  [25] 47.75 64.25 63.75 63.75 63.75 47.25 47.25 47.25 47.50 64.00 64.00 64.00
##  [37] 47.50 47.25 47.25 47.50 47.50 47.25 47.50 47.50 47.25 47.25 47.50 47.50
##  [49] 47.25 64.25 47.50 47.25 47.50 64.25 47.50 64.00 47.50 64.00 47.50 47.25
##  [61] 47.50 47.50 47.50 47.50 47.50 47.25 47.50 47.50 47.50 47.50 47.75 47.50
##  [73] 47.25 47.25 47.50 47.50 47.50 47.50 47.50 47.50 47.50 47.25 47.25 64.00
##  [85] 47.50 47.50 47.50 47.25 47.25 47.50 47.25 47.25 47.25 47.25 47.50 47.50
##  [97] 47.50 47.50 64.00 47.25

Pixi mode in ms

##   [1] 47.50 47.50 47.50 47.50 47.25 47.25 47.25 47.50 47.25 47.25 47.50 47.50
##  [13] 30.50 47.50 47.25 47.25 47.25 47.50 47.50 47.25 47.50 47.50 47.50 47.50
##  [25] 47.25 30.75 47.50 47.50 47.25 47.25 30.75 30.50 47.50 47.50 47.50 47.25
##  [37] 47.50 47.50 47.50 47.25 47.50 47.50 47.50 47.50 47.50 47.50 47.50 47.50
##  [49] 47.50 47.25 47.50 47.50 47.25 47.50 47.50 47.50 47.50 47.50 47.50 47.25
##  [61] 47.50 47.50 47.50 47.50 47.25 47.50 47.25 47.25 47.50 47.50 47.50 47.50
##  [73] 47.50 47.50 47.50 47.50 64.25 47.50 47.50 47.50 47.50 47.50 47.25 47.50
##  [85] 47.50 47.50 47.75 47.50 47.50 30.75 47.50 47.25 47.50 47.50 47.50 47.50
##  [97] 47.50 47.50 47.50 47.50