Sensation and Perception Flashcards
(43 cards)
The Detection Question
The limits on our ability to detect very faint signals.
Involves absolute threshold
Absolute Threshold
the minimum amounts of energy in a sensory stimulus detected 50% of the time
the amount of energy that has an equal probability of being detected or not detected
ex. how close to we have to be to see the candle on the mountain, how far from the clock can we be to still heat it tick
Subliminal
Stimuli detected less than 50% of the time, not enough energy to be sensed
What is subliminal advertising and does it work?
Giving hints to people that they cannot consciously detect that are supposed to be influencing them to buy something. No! it doesn’t work.
Signal Detection Theory
our ability to detect a faint sensory signal
has to do with the decision-making part of it, is there enough stimuli to decide that it is present
ex. a juror has to decide if they have enough info to choose innocent or guilty. people may have the same amount of information(stimuli) but choose differently if it is enough evidence to make a decision
4 types of outcomes in signal detection
a hit - saying yes when there is a signal
a miss - saying there is no signal when there is one
a false alarm - saying yes when there is none
a correct rejection - saying no when there is none
is detecting cancer on an x-ray a signal detection test
yes
lax decision criteria
-a tendency to say yes with little evidence
-makes many false alarms
-has few misses
strict decision criteria
-only says yes with a lot of evidence
-makes many misses
-has few false alarms
the difference question
how different does a stimulus have to be for us to notice the difference
difference threshold
just noticeable difference
jnd
the minimum difference between two stimuli to ne detected 50% of the time
Weber’s Law
for each type of sensory judgment that we can make, the measured difference threshold is a constant fraction of the standard stimulus value used to measure it
ex. for touch we can notice something 1/10 different. One box is 10 pounds, the other box will have to be 11 pounds to notice a difference.
- we notice proportional differences and not absolute differences
the scaling question
how do we perceive scale stimulus compared to how it physically is? if a light is 10 times brighter perceptually, how much brighter is the light physically?
Stephen’s Power Law
the perceived stimuli is changed by the increase of the physical change to a constant power.
ex. a light is 5 times brighter, physically it is 5^2 times brighter. that same light is 8 times brighter, physically is is 8^2 times brighter.
sensory adaptation
sensitivity to unchanging stimuli disappears over time (not including intense, painful stimuli)
ex. a humming of an air conditioner may bother you at first but eventually you won’t notice it
- we have adapted to detect changes, not constants
wavelength
700 - 400 = red - violet
amplitude
amount of energy in a wave
ex. larger amplitude = brighter light, larger amplitude = louder sound
frequency
number of waves in a second
higher pitch = higher frequency
lower pitch = lower frequency
McGurk Effect
conflicting audio and visual stimuli, brain blends sensory info together
- if u listen to sound “ba” and see someone mouthing “ga” you actually hear “da”
transduction
receptor cells transfer energy (like light, sound, touch) to neural impulses the brain can understand
retina
contains light receptor cells, back of the eyeball, where transduction occurs
made up of 3 layers, ganglion, bipolar, receptors (cones and rods)
cornea
clear, hard surface of the eye, bends light waves to focus on the retina
pupil
tiny hole where light enters the eye
iris
colored part of eye, muscle that makes pupil bigger/smaller to allowed more/less light in
