Chapter 2 Flashcards
What is a Psychophysical scale?
A scale where people rate their psychological experiences as a function of the level of a physical stimulus
What is the Scoville scale?
Its a psychophysical scale that measures our experience of piquancy (hotness) in different concentrations of capsaicin
The _______ scale measures the psychological construct of loundess
Decibel
What is the “Just Noticable Difference” (JND)?
Its the smallest amount of physical change observers notice as a perceptual change
The psychophysical apprpach focuses on the relation between what?
Physical properties and perception
Explain the “Method of Limits”
A participant must decide of a stimulu is present or not present at a number of different levels of intensity
Increasing stimulus intensity until its perceived (ascending series) or reducing it until its not percieved (descending series)
What are 2 “cons” for the Method of Limits?
Induces errors of Habituation (people disengage from experience) and of Anticipation (people engage too much, anticipating instead of percieving)
What is a “pro” for the method of limits?
It can track threshold changes over time
What is the difference between the Aboslute Threshold and the Difference Threshold?
An Absolute threshold is the point where a physical stimulation enters into consciousness, its the smallest amount of a stimulus necessary for an observer to detect it.
A Difference threshold is the same as the just noticeable difference, Its the smallest difference between two stimuli that can be detected (eg. holding 2 weights and attempting to determine if the masses are the same or different)
Detecting the absolute threshold is a ____ or ____ question.
Yes or no (you can either detect it or not)
The “absolute threshold” is also called what?
limen (from subLIMINal)
For an Absulute threshold and the difference threshold, the minimun stimulus energy (or chemicals) are required to be detected ____% of the time, what is another name for this percentage?
50% = Point of Subjctive Equality (PSE)
The PSE designates the settings of two stimuli at which the observer experiences them as identica
since 50% is the difference point between two stimuli, the upper difference threshold would be _____ and the lower difference would be _____. The difference in threshold calculation would be _____ - _____ divided by ___.
0.75, and 0.25.
0.75-0.25 divided by 2
The difference threshold is a judgement made between the _________ and _________ stimuli
Standard (doesnt change) and comparison (changes) stimuli (both are well over the absolute threshold)
eg. present a 100g standard vs multiple comparison stimuli, and then ask if there is a difference
What is the difference between an ascending series and a descending series? What are other names for this?
An ascending series (or an ascending staircase) is one in which a stimulus gets increasingly larger along a physical dimension.
A descending series (or a descending staircase) is one in which the stimulus gets increasingly smaller along a physical dimension.
Also called adaptive testing and the staircase method
The point at which people change from detecting to not detecting a stimuli (and vice versa) is known as the what?
Crossover point
Typically, the threshold will be different when measured by the ascending method versus by the descending method. Why?
With ascending series, people are likely to claim that they can detect a stimulus when in fact the stimulus is below the threshold. With descending series, people are likely to claim that they cannot detect a stimulus when it actually is above the threshold.
Explain the Two-point touch threshold
The minimum distance along the skin at which two touches are perceived as two touches and not one (if they are super close together they will feel like only one thing is touching)
If a person feels only one touch, then it is ________ the threshold, but if the person feels two touches, then they are ______ the threshold
Below; above
Does the two-point touch threshold vary across our skin?
Yes, our fingers can detect two touches even when close, but the skin on our backs requires a greater distance to feel two touches
What is the method of constant stimuli?
Its where you present the observer with a set of stimuli (some are below and some are above the threshold) that are at random, and the observer says “yes” when stimulus is percieved.
Explain how an audiologist uses the method of constant stimuli. (to test patients for hearing thresholds)
The audiologist will present the patient with an assortment of louder and softer tones to detect. if that threshold is higher than it should, then maybe that person is a candidate for hearing aids (for some frequencies, a person may be impaired but for others have normal hearing)
What are the pros and cons for using the method of constant stimuli
Pro = it gives a good estimate of the threshold (if you do it a lot of times)
Cons = its very time consuming (must know proper range) and it cant measure threshold changes over time as someones adaptability will change
eg. in dark adaptation
