AP Psychology Practice Test 2026 – 400 Free Practice Questions to Pass the Exam

The key concept of psychophysics focuses on the relationship between physical stimulus intensity and sensory experience. Psychophysics is a branch of psychology that quantitatively investigates the relationship between the physical properties of stimuli (like brightness, loudness, or weight) and the perceptions or experiences they produce in observers. This area of study seeks to understand how varying physical intensities of stimuli influence our sensory processes and ultimately our perceptions of the world around us.

For instance, psychophysicists might explore how much brighter a light must be in comparison to another light for a person to perceive a difference. This is often related to concepts like the just noticeable difference (JND) and Weber's Law, which highlight how changes in stimuli relate to the perceived changes in sensation.

The other concepts mentioned, such as the dual nature of light and matter, the interaction between mind and body, and the psychological interpretation of quantum mechanics, do not directly address the fundamental aim of psychophysics, which is to quantitatively measure and understand sensory perception in relation to physical stimuli.