1.2 Thresholds and the Dawn of Psychophysics

Question 1

What was the study of the senses early on?

Answer 1

A mix of experimental science and philosophy

Question 2

Who was Gustav Fechner?

Answer 2

A nineteenth-century German Scientist who developed the field of Psychophysics.

Question 3

What interested Gustav Fechner?

Answer 3

The relationship between mind and matter.

Question 4

What philosophical debate did Gustav Fechner’s interest’s place him?

Answer 4

Between the debate of Dualism and Materialism.

Question 5

What Philosophical Idea do Duelists hold?

Answer 5

Dualists believe that the mind has en existence separate from the material world of the body.

Question 6

What Philosophical Idea do Materialists hold?

Answer 6

Materialists hold that the mind is not separate from the material world. They believe that the mind is what the brain does.

Question 7

What did Gustav Fechner propose to the debate of Dualism and Materialism.

Answer 7

Gustav Fechner proposed to split the difference by imagining that the mind, or consciousness, is present in all of nature.

Question 8

What is Panpsychism, who and what does this idea extend to?

Answer 8

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.

Question 9

What hypothesis Gustav Fechner develop while recovering his eyesight in 1850?

Answer 9

Fechner believed it to be possible that one could describe the relationship between the mind and body using mathematics.

Question 10

What is Psychophysics?

Answer 10

Psychophysics is the description of the relationship between sensation (mind) and the energy (matter) that gives rise to sensation.

Question 11

Which German colleague inspired Gustav Fechner?

Answer 11

Ernest Weber.

Question 12

What general sensation was Ernest Weber interested in?

Answer 12

Touch.

Question 13

What was Ernest Weber’s compass like device used to measure?

Answer 13

The smallest distance between two points that was required for a person to feel touch on two points of the skin instead of one.

Question 14

What is the Two-Point Touch Threshold?

Answer 14

The smallest distance between two points that was required for a person to feel touch on two points of the skin instead of one.

Question 15

What did Ernest Weber discover?

Answer 15

He discovered that the smallest detectable change in stimulus, is a constant proportion of the stimulus.

Question 16

What is the JND or “Just Noticeable Difference?”

Answer 16

The difference required for detecting a change in weight or the difference required for selecting a change between the standard and comparison stimulus.

Question 17

What is the Difference Threshold?

Answer 17

The difference Threshold is the smallest change in stimulus that can be detected.

Question 18

What is Weber’s ratio rule?

Answer 18

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.

Question 19

What are Weber Fractions?

Answer 19

The constant proportionality in Weber’s Law

Question 20

What is the definition of Weber’s law?

Answer 20

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

Question 21

What are the components for S = k log R?

Answer 21

(S) is the psychological sensation, which is equal to the logarithm of the physical stimulus (log R), multiplied by constant (k)

Question 22

What does S=k log R describe?

Answer 22

The equation describes the fact that our psychological experience of a particular stimulus increases less quickly than the actual physical stimulus.

Question 23

What is Fechner’s Law?

Answer 23

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.

Question 24

What is the Absolute Threshold?

Answer 24

The minimum intensity of a stimulus that can be detected.

Question 25

What is the Method of Constant Stimuli?

Answer 25

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.

Question 26

How can we measure an absolute threshold?

Answer 26

Using the Method of Constant Stimuli.

Question 27

What percentage is usually dictated as the threshold in a Constant Stimuli test?

Answer 27

50%

Question 28

Why’s is 50% designated as an individual’s absolute threshold?

Answer 28

Because of variability on the nervous system, stimulus close to the threshold will be detected sometimes and missed others.

Question 29

What test is a more efficient way of measuring an individuals absolute threshold?

Answer 29

The Method of Limits.

Question 30

Define Method of Limits.