1.2 Thresholds and the Dawn of Psychophysics Flashcards
What was the study of the senses early on?
A mix of experimental science and philosophy
Who was Gustav Fechner?
A nineteenth-century German Scientist who developed the field of Psychophysics.
What interested Gustav Fechner?
The relationship between mind and matter.
What philosophical debate did Gustav Fechner’s interest’s place him?
Between the debate of Dualism and Materialism.
What Philosophical Idea do Duelists hold?
Dualists believe that the mind has en existence separate from the material world of the body.
What Philosophical Idea do Materialists hold?
Materialists hold that the mind is not separate from the material world. They believe that the mind is what the brain does.
What did Gustav Fechner propose to the debate of Dualism and Materialism.
Gustav Fechner proposed to split the difference by imagining that the mind, or consciousness, is present in all of nature.
What is Panpsychism, who and what does this idea extend to?
Pansychism is an idea developed by Gustav Fechner that proposes that the mind exists in all property, of all matter.
Pansychism extends not only to humans, but animals and inanimate objects as well.
What hypothesis Gustav Fechner develop while recovering his eyesight in 1850?
Fechner believed it to be possible that one could describe the relationship between the mind and body using mathematics.
What is Psychophysics?
Psychophysics is the description of the relationship between sensation (mind) and the energy (matter) that gives rise to sensation.
Which German colleague inspired Gustav Fechner?
Ernest Weber.
What general sensation was Ernest Weber interested in?
Touch.
What was Ernest Weber’s compass like device used to measure?
The smallest distance between two points that was required for a person to feel touch on two points of the skin instead of one.
What is the Two-Point Touch Threshold?
The smallest distance between two points that was required for a person to feel touch on two points of the skin instead of one.
What did Ernest Weber discover?
He discovered that the smallest detectable change in stimulus, is a constant proportion of the stimulus.
What is the JND or “Just Noticeable Difference?”
The difference required for detecting a change in weight or the difference required for selecting a change between the standard and comparison stimulus.
What is the Difference Threshold?
The difference Threshold is the smallest change in stimulus that can be detected.
What is Weber’s ratio rule?
That virtually every measure, a constant ratio between the change and the standard could describe the threshold of detectable change. Except for extreme stimuli that reaches the minimum or maximum of our senses.
What are Weber Fractions?
The constant proportionality in Weber’s Law
What is the definition of Weber’s law?
The principle describing the relationship between stimulus and resulting sensation that says that the JND is a constant fraction of the comparison stimulus. Ex. 1/40
What are the components for S = k log R?
(S) is the psychological sensation, which is equal to the logarithm of the physical stimulus (log R), multiplied by constant (k)
What does S=k log R describe?
The equation describes the fact that our psychological experience of a particular stimulus increases less quickly than the actual physical stimulus.
What is Fechner’s Law?
A principle describing the relationship between stimulus and resulting sensation that says the magnitude of subjective sensation increases proportionally to the logarithm of the stimulus intensity.
As the intensity of a physical stimulus increases, a larger change in that physical stimulus is required to produce a just detectable difference in sensation.
What is the Absolute Threshold?
The minimum intensity of a stimulus that can be detected.
What is the Method of Constant Stimuli?
A psycophysical method in which many stimuli, ranging from rarely to almost always perceivable (or rarely to almost always perceivably different from a reference stimulus), are presented one at a time. Participants then respond to each presentation: “yes/no,” “same/different,” etc.
How can we measure an absolute threshold?
Using the Method of Constant Stimuli.
What percentage is usually dictated as the threshold in a Constant Stimuli test?
50%
Why’s is 50% designated as an individual’s absolute threshold?
Because of variability on the nervous system, stimulus close to the threshold will be detected sometimes and missed others.
What test is a more efficient way of measuring an individuals absolute threshold?
The Method of Limits.
Define Method of Limits.
