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Sensation is. … the detection and encoding of stimuli. Psychophysics. of the mind. tangible or measurable. Absolute threshold:. …the minimum magnitude of stimulus that can be detected 50% of the time. The Ideal Threshold (does not exist in nature). The Absolute Threshold.
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Sensation is …the detection and encoding of stimuli. Psychophysics of the mind tangible or measurable
Absolute threshold: …the minimum magnitude of stimulus that can be detected 50% of the time.
The Ideal Threshold (does not exist in nature)
Difference threshold: …the minimum amount a stimulus must change in order for the change in sensation to be detected 50% of the time. the jnd
How well do you understand the statement: “The absolute threshold is really just a special type of a difference threshold.” • I understand. • I do not understand. • I will have to think about it more.
In the 1830s, E.H. Weber Weber Fraction = the amount of stimulation necessary to result in a “just noticeable difference” is a constant fraction of the stimulus intensity e.g., for weight: k = 1/50 (the Weber Fraction) 1 lb. = 2 lb. = 1/5 lb. 50lb. 100 lb. 10 lb. The Weber Fraction varies with sensory modality.
Gustav Fechner (1801 – 1887) jnds are units of psychological changes in sensation proposed a law describing the relationship between psychological and physical events: S = k log I Psychological Weber Physical (units: jnds) Fraction (units: lbs., dB, etc.)