A psychologist is interested in the effect of physical attractiveness on ratings of punishment assigned to a driver in an automobile accident. Participants read an account of the accident and received a written description of a physically attractive or unattractive defendant. The manipulation of attractiveness would be an example of a(n) _____ manipulation.

The physically attractiveness of defendants or physical unattractiveness of defendants is known as the independent variable or the manipulated variable because it can be changed in order to study the outcome of something.

In order to test for something, there is a need for one to change one variable so as to know what we will get after changing that variable and that is known as manipulation. One of the Important kind of manipulation is known as the straight-forward manipulation.

STRAIGHT-FORWARD manipulation is when participants in an experiment are given written description about a variable( an independent variable).

If you look at the question again, we can see that the Researcher that is the psychologist gave out the written material to his or participants.