Chapter 4: Sensation

Question 1

Weber’s Law (p. 137-139)

Answer 1

the size of the difference threshold is proportional to the intensity of the standard stimulus

the more intense the stimulus, the more stimulus intensity has to be increased before observer notices a change

ex) difference between a backpack weighing 25lbs and one weighting 25.5 lbs, but you won’t notice a smaller difference in lbs

Question 2

Fechner’s Law

Answer 2

strength of a sensation is proportional to the logarithm of physical stimulus intensity

Question 3

Muller

Answer 3

key to sensation lies simply in which nerves are being stimulated

stimulation of the optic nerve causes the sense of seeing ; stimulation of the auditory nerve cause the sense of hearing

Question 4

sensory coding

Answer 4

(Muller)

the process through which nervous system represents the qualities of the incoming stimulus

Question 5

perceptual sensitivity

Answer 5

ability to detect a signal

Question 6

decision criteria

Answer 6

organism’s rule for how much evidence it needs before responding

Question 7

signal detection theory

Answer 7

perceiving or not perceiving a stimulus is actually a judgement about whether a momentary sensory experience is due to background noise alone or to the bckgrnd noise + a signal

how people make decisions as to when a particular stimulus is present & when it isnt

Question 8

What 2 factors are at work in signal detection?

Answer 8

1. Sensitivity (how well subject can see/hear stimulus

2. Response Bias (how willing a subject is to say he heard stimulus when he is not certain)

Question 9

payoff matrix

Answer 9

pattern of benefits and costs associated with certain types of responses

(ratio of amount of reward for success to reward for failure)

Question 10

visible spectrum

Answer 10

light that we can see out of the broader electromagnetic spectrum

(ranges from 400-700)

Question 11

amplitude

Answer 11

determines brightness

Question 12

Fovea

Answer 12

area at the pupil’s center where cones are plentiful and visual acuity is greatest

Question 13

Optic Nerve

Answer 13

bundle of fibers that proceeds from each retina to the brain

Question 14

Blind spot

Answer 14

where there are no photo receptors (p.164)

Question 15

Rods

Answer 15

photoreceptors in the retina that respond to lower light intensities and give rise to colorless (achromatic)

Question 16

Rods (night vision)

Answer 16

photoreceptors in the retina that respond to lower light intensities and give rise to colorless (achromatic) sensations

contain photopigment rhodipsin

Question 17

Cones (day vision)

Answer 17

photoreceptors in the retina that respond to greatet light intensities and give rise to color (Chromatic) sensations

Question 18

Duplex Theory of Vision

Answer 18

Rod Photo receptors are much more sensitive to low levels of light and over a broader range of wave

Question 19

Duplex Theory of Vision

Answer 19

Rod Photo receptors are much more sensitive to low levels of light and over a broader range of wave frequencies than are the cone receptors

Unlike the cone receptors, they do not code for color

Question 20

Young-Helmholtz (Trichromatic) Theory

Answer 20

human color vision= 3 sets off cones

• one is sensitive to a wavelength of 440 nm (blue)
• one is sensitive to wavelength of 530nm (green)
• one is sensitive to wavelength of 570nm (orange/red)

Question 21

Why do we see multitudes of different hues by the use of only 3 color pigments in the cones?

Answer 21

“Recipe book” by whicyh each unique pattern is translated in its own color experience psycholohicall

Question 22

Why do we see multitudes of different hues by the use of only 3 color pigments in the cones?

Answer 22

“Recipe book” by which each unique pattern is translated in its own color experience psychologically

Question 23

Opponent Process Theory (p.172)

Answer 23

proposes 3 pairs of color antagonists: red-green, blue-yellow, and white-black

Excitation of neurons sensitive to one member of a pair automatically inhibits neurons sensitive to the other member q

Question 24

Feature Detectors

Answer 24

neurons in retina/brain (retina’s receptive fields & occipital cortex) that respond to specific attributes of the stimulus, such as movement, orientation etc.

Question 25

brightness constrast

Answer 25

effect that makes a stimulus LOOK much brighter on a dark background than on a bright one

Question 26

Lateral Inhibition

Answer 26

activity in one neuron inhibits adjacent neuron’s responses

Question 27

Hue

Answer 27

attribute that distinguishes blue from red from green; attribute shared by shades of orange

Question 28

Brightness

Answer 28

dimension of color that differentiates black from white and the various shades of gray in between

Question 29

Saturation

Answer 29

“purity” of a color ; the extent to which it is chromatic rather than achromatic

Question 30

cornea

Answer 30

transparent layer forming the front of the eye –focusing vision

Question 31

iris

Answer 31

responsible for controlling the diameter and size of the pupil (amount of light reaching the retina

Question 32

pupil

Answer 32

hole located in the center of the iris of the eye that allows light to strike the retina

Question 33

lens

Answer 33

When you try to focus on something the lens changes shape and then focuses the incoming light onto the retina

Question 34

Retina

Answer 34

area in the back of the eye that contains rods and cones