Scoville scale
A measure of our detection of the amount of an ingredient called capsaicin in chili peppers
Capsaicin
The active ingredient in chili peppers that provides the experience of hotness, piquancy, or spiciness
Psychophysical scale
A scale on which people rate their psychological experience as a function of the level of physical stimulus
Method of limits
Stimuli are presented in a graduated scale, and participants must judge the stimuli along a certain property that goes up or down
Absolute threshold
The smallest amount of a stimulus necessary to be detected
Difference threshold (JND)
The smallest difference between two stimuli that can be detected
Ascending series
A series in which a stimulus gets increasingly larger along a physical dimension
Descending series
A series in which a stimulus gets increasingly smaller along a physical dimension
Crossover point
The point at which a person changes from detecting to not detecting a stimulus or vise versa
Two point touch threshold
The minimum distance at which two touches are perceived as two touches and not one
Method of constant stimuli
A method whereby the threshold is determined by presenting the observer with a set of stimuli, some above threshold and some below it, in a random order
Method of adjustment
A method whereby the observer controls the level of the stimulus and adjusts it to be at the perceptual threshold
Point of subjective equality (PSE)
The settings of two stimuli at which the observer experiences them as identical
Sensitivity
The ability to perceive a particular stimulus; it is inversely related to threshold
Magnitude estimation
A psychophysical method in which participants judge and assign numerical estimates to the perceived strength of a stimulus
Response compression
As the strength of a stimulus increases, so does the perceptual response, but the perceptual response does not increase by as much as the stimulus increases
Response expansion
As the strength of a stimulus increases, the perceptual response increases even more
Steve’s power law
A mathematical formula that describes the relationship between stimulus intensity and our perception; it allows for both response comprehension and expansion
Catch trial
A trial in which the stimulus is not presented
Forced choice method
A psychophysical method in which a participant is required to report when or where a stimulus occurs instead of whether it was perceived
Signal detection theory
In every sensory detection or discrimination, there is both sensory sensitivity to the stimulus and a criterion used to make a cognitive decision
False alarm
An error that occurs when a non-signal is mistaken for a target signal
Miss
An error that occurs when an incoming signal is not detected
Correct rejection
Occurs when a non-signal is dismissed as not detected
Hit
When a signal is detected and present
Criterion
An internal cutoff, determined by the observer, above which the observer makes one response and below which the observer makes another response
Sensitivity (signal detection theory)
The ease or difficulty with which an observer can distinguish signal from noise
Receiver operating characteristic (ROC) curve
A plot of false alarms versus hits for any given sensitivity, indicating all possible outcomes for a given sensitivity
Sensorineural hearing loss
Permanent hearing loss caused by damage to the cochlea or auditory nerve
Conductive hearing loss
The inability of sound to be transmitted to the cochlea
Audiologist
A trained professional who specializes in diagnosing hearing impairments
Audiometer
A device that can present tones of different frequencies, from low in pitch to high in pitch, at different volumes from soft to loud
Audiogram
A graph that illustrates the thresholds for the frequencies as measured by the audiometer
Optometrist
A trained professional who specializes in diagnosing visual impairments and diseases
Myopia
A condition causing an inability to focus clearly on far objects, also called nearsightedness; occurs because accommodation cannot make the lens thin enough
Presbyopia
A condition in which incoming light focuses behind the retina, leading to difficulty focusing on close-up objects; common in older adults, in whom the lens becomes less elastic