Sensation
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1. The study of how physical sources of stimulation ( light,sound, etc.) relate to our experience in the form of sensation is called psychophysics.
2. Common characteristics that relate to functioning of our sensory systems are: thresholds, signal detection, and sensory adaptation.
2.1. Absolute threshold is the smallest amount of stimulus a person can reliably detect. Difference threshold or just noticeable difference is the minimal difference between two stimuli that a person can reliably detect.
2.1.1. Weber's Law states that the amount of change in a stimulus needed to detect a difference is given by a constant ratio or fraction called a constant, of the original stimulus.