Answer:
The flynn effect generates a bell curve. A bell curve is also know as a normal distribution curve. It is known as normal because it is the curve that most populations show when computing an statistical analysis.
The IQ score among different people is an example of a bell curve. Some people will have very low IQs, some will have very high IQs, but most people will fall somewhere in the middle. The Flynn effect simply changes the values of the curve, but not its shape. It is still a bell curve, but with higher values.