Measurement Flashcards
(18 cards)
Subjective meaures
Likert scales - labelled levels
Anchored scales - proper scales
only endpoints are labelled
limited number of responses
Subjective measures - Visual analogue scale
only endpoints are labelled
distance to anchors are measured
Fechner’s concept of Psychophysics
stimulus ( physical)
excitation ( psychophysical)
sensation ( phenomenal)
Fechner’s concept
uses simple questions - how much of something can be detected - absolute threshold
How much can something be changed before the change is detected - difference threshold
What is the absolute sensory threshold
the smallest detectable limit of sensory stimulus - it can also be described as the lowest intensity at which a stimulus can be recognised or detected
Difference threshold
rather than the detection of a sensation this looks at the detection of a difference in a sensation
known as the Just noticeable difference
Methods of constant stimuli
Pairs of stimuli are presented with one always the same ant the participant indicates if they are the same or not
two alternative - force - choice- task
the JND is taken as the point at which discrimination is made
Methods of limits
staircase method
Measuring performance
accuracy
sometimes task accuracy is a more complicated measure
signal detection theraphy
not all responses to a stimulus or absent of stimulus are correct
signal detection theory assumes there is noise around any stimulus
signal detection theraphy
not all responses to a stimulus or absent of stimulus are correct
signal detection theory assumes there is noise around any stimulus
what is the difference between detection and discrimination
detection is the goal to detect the presence of a stimulus
discrimination the goal is to detect the presence of a difference between two or more stimuli
Sensitivity and Criterion
changes in performance can be a result of a change in sensitivity or in criterion
changes in discrimination are usually more interesting
Johnson, K,J Fredrickson 2005 - white and black faces tested - racial bias
Speed of response
different mental processes require different lenghts of time
Measuring the speed of mental processes
Herman Von Helmholtz
Frog legs experiment
neural impulses travel at 100 km/ hr
Donder’s method of subtraction
Simple reaction time vs Go/ No-go task vs choice task
can reaction time reveal mental processes
Donder’s ( 1968) subtraction method and Sternberg’s ( 1969) addition contentious
one process can begin before another is complete
