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15 Cards in this Set
- Front
- Back
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Why is psychophysics?
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The study of relationship between sensory experience and sensory stimuli
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What is Webers Law (state it verbally and state it using an equation)
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The amount that a physical stimulus needs to be increased to be perceivably different is a constant ratio relative to the concentration
k = dI/I |
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What is Fechner’s Law (again state it both verbally and with an equation)
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There is a log-function psychophysical relationship between physical stimulus intensity and sensory intensity (which was constructed by adding up JNDs)
S = klog(I) S = sensation intensity I = Physical stimulus intensity |
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Describe the Method of limits
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Often used in threshold detection work - increasing/decreasing discrete concentration steps are presented and a change in response is noted.
Many trials are performed and the average change point is calculated. |
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Describe the method of constant stimuli
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Two samples are presented, one of which is always the same control of constant stumuli. Subject needs to respond "greater than" or "Less than"
Comparison sample presented at various intensities & many reps - psychometric function (s-shape curve) results |
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Describe the method of adjustment
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The subject is given control over stimulus intensity and adjusts it to match a standard - not widely applicable in foods
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Describe the “method of single stimuli”
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Historical term for the use of rating scales
Can be used to construct the psychometric curve |
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Describe the psychophysical power law (again state it both verbally and with an equation)
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Sensory intensity perceptions are a power function of stimulus intensity, and each stimulus has its own characteristic exponent
S = kI^n n = characteristic exponent --> almost always <1 with olfactory sensations |
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Sketch the power law in linear/linear and log/log coordinates
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Linear: concave up n >1 / straight n=1 / concave down n<1 quicker rise upward)
Log: straight line (larger n = steeper slope) |
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What is the meaning of a power function that has an exponent less than 1 (as is the case with most olfactory sensations)?
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A greater rise in stimuli intensity is required to increase the sensory intensity an proportion at high intensities - this matches what weber's law states
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What is cross modality matching?
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Matching the intensity of an experienced stimuli by adjusting the intensity of a different stimuli: one continua is scaled as a function of the other
(Can be used to predict power function exponents) |
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What are the advantages of equation 2.5 on page 37:
R = RmaxC / (k + C) for describing the relationship of stimulus and sensation compared with the Stevens and Fechner equations? |
Because this function approaches a maximum response, while the Fechner and Steven equations continue upward indefinitely
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What are the 4 main types of consumer testing in regard to the type of panel & product placement?
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- Employee panels
- Standing external panels - CLT - HUT |
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What is the Friedman test?
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A non-parametric test equivalent to the 2-way ANOVA without interactions
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What is the hedonic scale?
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A 9-point discrete scale with words chosen determined using Thurstonian methods. The words were chosen based on equal-interval spacing. This is important since it means we can apply parametric methods when using the scale.
The scale is said to have ruler-like properties. |
