<p><strong>Short answer</strong><br>
In the case of simple stimuli, visual and auditory stimuli can be offset between <strong>25 and 50 ms</strong> and still be perceived as coming from one and the same same event.</p>

<p><strong>Background</strong><br>
The question can be re-phrased as <em>what is the <strong>window of integration</strong> of <strong>intersensory asynchrony</strong> in case of visual and auditory stimuli</em>? </p>

<p>A well-known example where these two stimulus modalities are perceived as separate, while they are in fact coming from the same event, is a thunder heard <em>after</em> lightning. This is caused by the fact that sound travels at a speed much slower than light, and hence a thunder can lag lightning by seconds.</p>

<p><img src="https://i.sstatic.net/P4Q3J.png" alt="Thunder lightning"><br>
<sup>source: <a href="http://www.grc.nasa.gov/WWW/k-12/airplane/sound2.html" rel="nofollow noreferrer">NASA</a></sup></p>

<p>In many instances, however, a multimodal perception is actually perceived as being synchronous, while they are in fact offset in time due to differences in physical characteristics of the stimuli. Take the storm as an example - when it is far away, the thunder is perceptually dissociated from the lightning, because the sound lags the light by seconds. But when the thunderstorm is close enough, the auditory crack and visual lightning are perceived as synchronous, while in fact they are still offset because of the sound travelling so much slower than light. </p>

<p>So the question becomes, as you rightfully ask, what are the <em>margins</em> in which stimuli across modalities can be asynchronous while perceived as one event? In other words, what is the <em>window of integration</em>? </p>

<p><a href="http://www.researchgate.net/profile/Jean_Vroomen/publication/43535149_Perception_of_intersensory_synchrony_a_tutorial_review/links/0fcfd506d6effbeaa1000000.pdf" rel="nofollow noreferrer">Vroomen and Keetels (2010)</a> conclude in their review on this topic that a stimulus asynchrony in the case of auditory beeps and visual flashes can be between <strong>25 and 50 ms</strong> and still be perceived as coming from the same event. </p>

<p>The window of integration between more complex stimuli can be much greater. For example, the window for <strong>speech and visual information</strong> can be as large as <strong>203 ms</strong>. Such large windows of integration point toward higher processes playing a role in the brain. Only temporal lags <strong>below 20 msec</strong> are expected to go <strong>unnoticed because of hard-wired limitations</strong> on the resolution power of the individual senses.</p>

<p>Hence, <a href="http://www.researchgate.net/profile/Jean_Vroomen/publication/43535149_Perception_of_intersensory_synchrony_a_tutorial_review/links/0fcfd506d6effbeaa1000000.pdf" rel="nofollow noreferrer">Vroomen and Keetels (2010)</a> argue there must be <strong>higher processes</strong> at work in the brain that actively synchronize percepts that are offset in time, but seem to belong to one and the same event. One such mechanism is referred to as <em><a href="https://acousticengineering.wordpress.com/tag/ventriloquist-effect/" rel="nofollow noreferrer">temporal ventriloquism</a></em>, which means that a <em>perceptual modality is <strong>actively shifted in time</strong> to match it with another modality</em>. This effect is most pronounced in visual stimuli, in that a visual percept is actively adjusted in time to match a sound or tactile stimulus. Likely visual percepts are shifted preferably by the brain, because the visual system is the slowest of all the senses.</p>

<p><sub><strong>Reference</strong><br>
<a href="http://www.researchgate.net/profile/Jean_Vroomen/publication/43535149_Perception_of_intersensory_synchrony_a_tutorial_review/links/0fcfd506d6effbeaa1000000.pdf" rel="nofollow noreferrer">Vroomen &amp; Keetels, <em>Att Percept Psychophys</em> 2010; <strong>72</strong>(4): 871-84</a></sub></p>

CC BY-SA 3.0
2016-06-02T07:35:57.980Z
2016-06-02T07:57:35.457Z
2016-06-02T07:57:35.457Z
AliceD
<p>I am developing a game where the music needs to be synchronized to the actual game logic. That means that some objects in the game react to events in the music. Of course, the music will never be completely synced to the output on the screen, so I need an indication of the time difference so I can sync the music manually to the game logic.</p>

<p>What is the average/maximum time for a human to still associate a visual event on the screen with an auditory musical event?</p>

CC BY-SA 3.0
2016-03-26T15:26:46.357Z
I would recommend doing a google scholar search for things like "audio-visual binding window". https://scholar.google.com/scholar?hl=en&q=audio-visual+binding+window&btnG=&as_sdt=1%2C7&as_sdtp=
Russell Richie
<perception><vision><hearing>
What is the maximum time difference to still associate an acoustic and visual event?
Max
# What is the maximum time difference to still associate an acoustic and visual event?

(Asked by: username_0 on 2016-03-23)

I am developing a game where the music needs to be synchronized to the actual game logic. That means that some objects in the game react to events in the music. Of course, the music will never be completely synced to the output on the screen, so I need an indication of the time difference so I can sync the music manually to the game logic.

What is the average/maximum time for a human to still associate a visual event on the screen with an auditory musical event?

**Tags:** perception, vision, hearing

> **Comments:**
> **username_1**: I would recommend doing a google scholar search for things like "audio-visual binding window". https://scholar.google.com/scholar?hl=en&q=audio-visual+binding+window&btnG=&as_sdt=1%2C7&as_sdtp=  

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## 1 answers

### Answer by username_2 on 2016-06-02. Score: 3

**Short answer**  
In the case of simple stimuli, visual and auditory stimuli can be offset between **25 and 50 ms** and still be perceived as coming from one and the same same event.

**Background**  
The question can be re-phrased as *what is the **window of integration** of **intersensory asynchrony** in case of visual and auditory stimuli*?

A well-known example where these two stimulus modalities are perceived as separate, while they are in fact coming from the same event, is a thunder heard *after* lightning. This is caused by the fact that sound travels at a speed much slower than light, and hence a thunder can lag lightning by seconds.

![Thunder lightning](https://i.sstatic.net/P4Q3J.png)  
source: [NASA](http://www.grc.nasa.gov/WWW/k-12/airplane/sound2.html)

In many instances, however, a multimodal perception is actually perceived as being synchronous, while they are in fact offset in time due to differences in physical characteristics of the stimuli. Take the storm as an example - when it is far away, the thunder is perceptually dissociated from the lightning, because the sound lags the light by seconds. But when the thunderstorm is close enough, the auditory crack and visual lightning are perceived as synchronous, while in fact they are still offset because of the sound travelling so much slower than light.

So the question becomes, as you rightfully ask, what are the *margins* in which stimuli across modalities can be asynchronous while perceived as one event? In other words, what is the *window of integration*?

[Vroomen and Keetels (2010)](http://www.researchgate.net/profile/Jean_Vroomen/publication/43535149_Perception_of_intersensory_synchrony_a_tutorial_review/links/0fcfd506d6effbeaa1000000.pdf) conclude in their review on this topic that a stimulus asynchrony in the case of auditory beeps and visual flashes can be between **25 and 50 ms** and still be perceived as coming from the same event.

The window of integration between more complex stimuli can be much greater. For example, the window for **speech and visual information** can be as large as **203 ms**. Such large windows of integration point toward higher processes playing a role in the brain. Only temporal lags **below 20 msec** are expected to go **unnoticed because of hard-wired limitations** on the resolution power of the individual senses.

Hence, [Vroomen and Keetels (2010)](http://www.researchgate.net/profile/Jean_Vroomen/publication/43535149_Perception_of_intersensory_synchrony_a_tutorial_review/links/0fcfd506d6effbeaa1000000.pdf) argue there must be **higher processes** at work in the brain that actively synchronize percepts that are offset in time, but seem to belong to one and the same event. One such mechanism is referred to as *[temporal ventriloquism](https://acousticengineering.wordpress.com/tag/ventriloquist-effect/)*, which means that a *perceptual modality is **actively shifted in time** to match it with another modality*. This effect is most pronounced in visual stimuli, in that a visual percept is actively adjusted in time to match a sound or tactile stimulus. Likely visual percepts are shifted preferably by the brain, because the visual system is the slowest of all the senses.

**Reference**  
[Vroomen & Keetels, *Att Percept Psychophys* 2010; **72**(4): 871-84](http://www.researchgate.net/profile/Jean_Vroomen/publication/43535149_Perception_of_intersensory_synchrony_a_tutorial_review/links/0fcfd506d6effbeaa1000000.pdf)


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