Ambiguity

In the image below, we see either two faces or a candlestick--not both at the same time.

Figure 7: Reverse optical illusion.

Phantom words by Diana Deutsch (UCSD):

• what word is heard and does it change? sound

Mysterious Melody by Diana Deutsch (UCSD):

• Can you identify a well-known melody with notes played in different octaves? scrambled / unscarambled
• This demonstrates use of previously acquired knowledge in peception.
• Visual example: an ambiguous image may be interpreted in a number of ways; (see here).
• Once told it is a dalmation, shapes of identifiable characteristics (ears, nose, tail etc.) begin to emerge to make it so.
• Audio example: shows importance of pitch (height) vs pitch class in melody.

Two melodies may seem scrambled if not separated by some feature (pitch height or timbre).

Figure 8: Overlapped melodies may be separated with timbre or register (pitch height).