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Science of the Mind | SP r = √SSxSSy |
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Science of the Mind | SP r = √SSxSSy |
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This illusion was first demonstrated by Diana Deutsch at the University of California, San Diego. The recording features overlapping sequences of repeating words or phrases, located in different regions of stereo space. As you listen to it, you’ll start to pick out specific phrases. However, none of the phrases are really there. Your brain is constructing them, in a bid to make sense of a meaningless noise. Indeed, you may find that the phrases you hear are related to what’s on your mind – for example, people who are dieting often hear phrases associated with food. This can be a very eerie experience.
The brain is constantly attempting to find meaning in things, even where there is no meaning. This can often lead us to experience illusions. Just as, when we look into a cloudy sky, we may see strange faces and figures, so when presented with ambiguous sounds, we may hear words and phrases that are not really there.
The CD is named after the first few tracks, which contain sequences of repeating words and phrases that arise simultaneously from different regions of space. These illusions should be heard through stereo loudspeakers that are placed in front of you, with one to your left and the other to your right. The words coming from the different spatial locations are offset from each other in time. As a result, listeners are given a palette of sounds from which to choose, and so can create in their minds many different combinations of sounds. After continuous exposure to these repeating words, listeners begin to 'hear' words and phrases that are not really there. These 'phantom words' are generated by the brain in an attempt to extract meaning from the chaos of sound that is presented.
Since the illusions develop with repetition, you need to listen to long segments in order to experience them fully. I suggest having a pen and paper in front of you, so that you can jot down the words and phrases that you hear. Most likely they will suddenly appear to change into different words and phrases as you continue listening. Whenever this happens, jot down the new ones that you hear. You will sometimes find that the left and right loudspeakers appear to be producing different words or part-words. When this happens, jot down separately the words you hear as coming from the speaker on the left, and those you hear as coming from the speaker on the right. Once the illusions have begun to appear, try turning your head in different directions, and even walking around the room. This often causes new words and phrases to emerge.
People often report hearing words that are related to what is on their minds. If they are on a diet, they may hear words that are related to food; if they have had a stressful day they may hear words that are related to stress; and so on. In fact, so strong is the influence of meaning on what is perceived, that people sometimes hear voices speaking in strange or unfamiliar accents, so as to create for themselves words and phrases that are particularly significant to them.
If English is your second language, you might find that some of the words you hear are in your native language. For example, native speakers of Chinese sometimes hear Chinese words, and native speakers of Spanish sometimes hear Spanish words. This impression can be so strong that people are sometimes convinced that such 'foreign' words have been inserted into the tracks, though in reality this never happens. Also, the words that are heard often appear to be spoken by different voices, each of which has a distinctive quality. Occasionally, people hear musical tones or other types of sound mixed in with the words.
So what is really being played? Each track contains either two words, or a single word that is composed of two syllables, and these are repeated over and over again. The identical sequence is played through both loudspeakers simultaneously, but when the first sound is coming from the loudspeaker on the left, the second sound is coming from the loudspeaker on the right; and vice versa. The identical sounds are repeatedly presented throughout each track, even though the words we think we hear appear to change from time to time.
Here is Phantom Word number 1. Below are just a few of the words and phrases that people have heard when listening to this example in a good listening space:
window, welcome, love me, run away, no brain, rainbow, raincoat, bueno, nombre, when oh when, mango, window pane, Broadway, Reno, melting, Rogaine
Here is Phantom Word number 2.
Here is Phantom Word number 3.
If you hear a high tone in one ear and a low tone in the other ear, decide which ear is hearing the high tone. Then reverse the earphones while the pattern is playing, and decide again which ear is hearing the high tone. Most righthanders hear the high tone on the right and the low tone on the left, regardless of how the earphones are positioned. Lefthanders and ambidextrous people are more varied in terms of where the high and low tone appear to be coming from. They are also more likely to obtain complex percepts, such as three different tones that often change their apparent locations in space.
This audio example is presented here in .WAV format.
The next sound file presents Deutsch’s Octave Illusion first with the two channels in stereo, then with the channels mixed together, and then with the channels in stereo again. Notice that when the two channels are mixed together you only hear a single tone with clicks occurring four times a second. Yet when the two channels are presented in stereo, a pattern of high and low tones occurs instead.
When listening to this sound file, it is best to use equipment with a flat frequency response, so as to avoid spectral distortion. Features that alter the signal in any way, such as spatialization features, should be turned off. Compression algorithms should be avoided, in particular for the stereo illusions. And make sure that the playback amplitude is not too high.
