The methods of the field of are used to investigate the relationship between the physical properties of a stimulus and observers' perception of the stimulus.

Psychophysics.

Explanation:

As the exercise briefly details, Psychophysics study the relationship between the physical properties of a stimulus and the observers' perception of the stimulus. It's the scientific study of a stimuli and the perception that an individual feels from the reaction to that stimuli. It's a stimulus-response study: psychophysics investigates how much of a stimuli we can detect. For example, when you feel a fabric why is it different from a watermelon? The texture, the smell, even taste. That's what psychophysics study, the perception of the stimuli.

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