What does psychophysics measure?

Psychophysics is a branch of psychology that focuses on understanding the relationship between physical stimuli and the psychological responses that these stimuli evoke. This field was pioneered by researchers like Gustav Fechner and is concerned with quantifying how changes in physical properties of stimuli, such as intensity or duration, correspond to changes in sensory perception and experience.

For instance, psychophysics explores questions like how much brighter a light must be for a person to notice the difference from dimmer light (the concept known as the just noticeable difference) or how loud a sound must be for it to be perceived as significantly different from a quieter sound. This process highlights the intricate connection between the external world and our internal perceptions, making it essential for understanding sensory modalities.

The other options do not align with the core focus of psychophysics. The first option pertains more to the cognitive aspects of psychology that involve emotional intelligence and memory. The third option relates to health psychology, investigating the interactions between psychological well-being and physical health, which is outside the scope of psychophysics. Lastly, while the fourth option touches on sensory perception, it does not specifically address the systematic measurement of the relationship between stimuli and responses, which is central to psychophysics.