Final answer:
The Thatcher Effect is a phenomenon where facial manipulations on an upside-down face are difficult to detect, highlighting the specialized nature of our visual system in processing upright faces.
Step-by-step explanation:
The Thatcher Effect refers to a phenomenon where changes to an upside-down face, such as inverted eyes and mouth, are not easily recognized by the human visual system. However, when the same face is flipped right-side up, the manipulations become strikingly apparent and the face looks grotesque. This demonstrates how our perceptual system is less skilled at interpreting facial features when they are arranged in an unusual orientation. This effect demonstrates that our brains have specialized processing for upright faces, which allows us to recognize and detect even subtle changes in them.
The correct answer to the question is: 1) A phenomenon where manipulated upside down faces are hard to recognize.