Sensation & Perception: Psychophysics Flashcards
Psychophysics
The study of the relationships between physical stimuli and psychological responses to the stimuli
Types of Threshold
Absolute Threshold
Difference Threshold
Absolute Threshold
The minimum of stimulus energy that is needed to activate a sensory system
Examples of Absolute Threshold
Taste = 1 tsp sugar in 2 gal of water Sight = 1 lit candle 30 miles away
Difference Threshold
The difference between 2 stimuli before they are perceived to be different.
Standard Stimulus
The difference from which a different threshold will be tried.
Comparison Stimulus
The stimulus that is compared to the standard stimulus.
Process to determine Difference Threshold
- Identify the standard stimulus
- Create different comparison stimulus
- Collect data on perceived difference
- Average of the perceived difference = Difference Threshold.
Just Noticeable Difference (JND)
The amount of change necessary to predict the different between two stimuli.
Difference Threshold Vs. Just Noticeable Difference
The Difference Threshold is the amount of stimuli needed to identify difference. JND is the number of Difference Thresholds because Difference Threshold should be considered in ratios of differences.
Weber’s Law
The rule that the change in stimulus intensity needed to produce a JND divided by the stimulus intensity of the standard stimulus is the constant. ? I/I = K ? where I is change in intensity and K is the constant. The smaller the K the more sensitive the stimuli.
Fechner’s Law
The rule that the intensity of the sensation increases more slowly as the intensity of the stimuli increases.
Steven’s Power Law
An equation that proves Fechner’s Law incorrect
Signal Detection Theory
Nonsensory factors influence what the subject says she sense.
Examples of Nonsensory Factors
Experiences
Motives
Expectations
