webers law Flashcards
What is luminance?
Quantity of light
What is brightness?
Describe the apparent quantity of light
What is a transducer function?
Describes how physical intensity is transformed into perceived intensity
What is a transducer?
A transducer is a process whereby physical stimuli are converted into neural signals
Who published to first book of psychopysics?
Gustav fechner in 19860s
What is the dependant variable ?
What the psychologist measures
what is independent variable ?
manipulating the data
What is a psychometric function?
A figure which shows relationship between physical quantity and some measurement of behaviour
What is noisy?
Observer did not always respond in same way to same stimuli
Explain experiment of 2AFC?
Two alternative forced choice test
- sit in the dark
- two beeps both with two bright lights
- lights not same intensity
- one has intensity =L
- one has extra intensity = delta L
- job is to detect the brighter intensity of light
Who came up with the wright and wrong case method?
Fechner
What is another name for wrong and write cases?
Multiple alternative forced choice test m
What are the two independent variable in 2AFC test?
baseline/ pedistal luminance =L
and extra luminance = delta L
What would happen if Transduction was flawless
The brighter light would always produce more bright light
however not always flawless its noisy
What does alot of overlapping of distribution mean?
The probability of incorrect responses was high correct response probability would be near 1 and half
What does little overlapping of distribution mean ?
The probability of correct responses is high the less intense light will never produce,
What does having same width on two curves mean?
Mild experience may be variable as intense experience
What does average brightness vary with?
Average brightness varies with the logarithm of luminance
How can you directly measure appearance?
You cannot it is impossible
How do you assign a value to SD of appearance noise?
Indirectly
ho demonstrated shadows?
Bouguers
Describe Bouguers experiment
- Two candles where light reflects from both candles reflect of the paper and cast shadows of the rod in between the candle and paper
- one candle set at a fixed distance - second candle increased distance until shadow disappeared
- Far enough till shadow just noticeable difference
What is just noticeable difference method of ?
Method of limits
Noticeability is what?
A judgment call no wrong or right answers
