When Ann went to her doctor, he gave her a hearing test. During the test, the doctor presented tones to Ann through earphones. The tones varied only along the loud-soft dimensions (from very loud to very soft). The doctor asked Ann to raise her hand whenever she heard a sound. The doctor was testing Ann's .

Absolute threshold

Explanation:

When Ann went to her doctor, he gave her a hearing test. During the test, the doctor presented tones to Ann through earphones. The tones varied only along the loud-soft dimensions (from very loud to very soft). The doctor asked Ann to raise her hand whenever she heard a sound. The doctor was testing Ann's absolute threshold .The minimum intensity of physical stimulation required to produce any sensation at all in a person is the absolute threshold

this null effect is caused by a weak manipulation and ineffective internal validity. in a scientific study, as the one dr. morimoto is trying to perfom, internal validity refers to the confidence placed in the cause-effect relationship and to how well an experiment is done and able to eliminate confounding variables.        

a factory opens that mass-produces light bulbs.

explanation:

not sure if that's an answer to your questions but this is an example! : )