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Intention and streaming

This demo works best over good headphones. If any of the instructions do not make sense, don't hesitate to contact Alex Billig at Please also bear in mind that perception of sound varies a lot from person to person, so do not worry if you hear these sounds differently to how they are described below.

First have a listen to the following repeated pattern of three tones. In each triplet, the first and third tones are a little higher in pitch than the second. After a short silence the pattern repeats, leading to a galloping rhythm.

Demo 1

When the middle tone in each triplet is much lower than the other two, the galloping rhythm can disappear. In the next example, after a few seconds you will probably hear two separate sequences of regularly repeating tones at the same time. One sequence will be high in pitch, and fast, and the other lower and slower.

Demo 2

Other sequences are more ambiguous. You may be able to hear the following example as a single galloping rhythm (as in Demo 1), or as two separate sequences (as in Demo 2). Your perception may change several times as you continue to listen, even though the tone pattern itself remains fixed.

Demo 3

During the experiment at the CBU, you will be asked to continuously report your percept as you listen to sequences like this. Whenever you perceive a single galloping rhythm (which we will refer to as "Integrated" as the three tones are integrated into a group), press the 'O' key on your keyboard. Whenever you perceive two separate sequences (which we will refer to as "Segregated" as the tones have segregated into two sequences), press the 'P' key on your keyboard. Please use the index and middle fingers of your right hand.

As soon as the sequence begins you should make a selection (once you have identified how you are hearing it). Each and every time your perception changes you should press (and release) the corresponding button. So in a sequence you might press once, twice, five times, twenty times or more. You do not need to keep the button pressed between changes and there is no right or wrong answer.

The website will not record your button presses, but please do use the 'O' and 'P' keys as described above, so that you get used to reporting what you are perceiving. The demo lasts for a minute.

Demo 4

Some people report that they can influence their perception of these ambiguous sounds. In the next example, try to hear the pattern as integrated throughout, by attending to all three tones in a triplet as a single group. If your perception changes to being segregated, try to force yourself to group the tones back together again. It may or may not be possible! Don't worry about pressing any buttons for now.

Demo 5

Now see whether you can force the sounds to segregate. Try doing so by paying attention to the faster, higher-pitched tones.

Demo 6

This time, try to force the sounds to segregate by paying attention to the slower, lower-pitched tones.

Demo 7

In the main experiment, you will sometimes be asked to "Listen neutrally", allowing your perception to take its natural course. On other trials you will be asked to try to integrate, with the instruction "Attend whole pattern". Sometimes you will be asked to try to segregate, with the instruction "Attend high tones" or "Attend low tones". Throughout, you will also use the 'O' and 'P' keys to report when you are hearing an integrated or segregated percept, respectively.

It is very important that you report what you are actually perceiving, not simply what you are trying to perceive. It may be that you can influence your perception, but if not please do not worry. The experiment relies on you reporting your actual experience as accurately as possible. Please press the button corresponding to your initial perception at the very beginning of the sequence, before you start trying to perceive the sequence in a certain way. Then press the relevant button each and every time your perception changes.

It might take some getting used to performing the two tasks at the same time (reporting your actual percept and trying to perceive the sequences in a particular way). Have a practice with each of these sequences.

Attempt to integrate (attend whole pattern): Demo 8
Attempt to segregate (attend high tones): Demo 9
Attempt to segregate (attend low tones): Demo 10

Please now send a brief email to Alex Billig at answering the following questions:

1. Did you understand the instructions, if not which parts?
2. Did you sometimes hear the sounds as integrated, and sometimes segregated?
3. Approximately how frequently did your perception change within a sequence?
4. Did you feel you could influence your percept by attending to certain tones?

Many thanks for your time.