Sensation and Perception - Ch 2 Research Methodology

Absolute Threshold

the smallest amount of a stimulus necessary to allow an observer to detect its presence

Ascending series

a series in which a stimulus gets increasingly larger along a physical dimension

Capsaicin

the active ingredient in chili peppers that provides the experience of hotness, piquancy, or spiciness

Catch trial

a trial in which the stimulus is not presented

Correct Rejection

in signal detection analysis, a occurs when a nonsignal is dismissed as not present

Criterion

is an internal cut off determined by the observer, above which the observer makes one response and below which the observer makes another response

Crossover point

the point at which a person changes from detecting to not detecting a stimulus or vice versa

D’ (d prime)

a mathematical measure of sensitivity

Descending series

a series in which a stimulus gets increasingly smaller along a physical dimension

Difference threshold (JND)

the smallest difference between two stimuli that can be reliably detected

Electroencephalography (EEG)

using electrodes to measure the electrical output of the brain by recording electric current at the scalp

False alarm

in signal detection analysis, when an error occurs whena anonsignal is mistaken for a target signal

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

Hit

in signal detection analysis, when a signal is detected when the signal is present

Magnetoencephalography (MEG)

using a magnetic sensor to detect the small magnetic fields produced by electrical activity in the brain

Magnitude estimation

a psychophysical method in which participants judge and assign numerical estimates to the perceived strength of a stimulus

Masking

the difficulty in seeing one stimulus when it is quickly replaced by a second stimulus that occupies the same or adjacent spatial locations

Method of adjustment

a method whereby the observer controls the level of the stimulus and “adjusts” it to be at the perceptual threshold

Method of constant stimuli

a method whereby the threshold is determined by presenting the observer with a set of stimuli, some above the threshold and some below it, in a random order

Method of limits

stimuli are presented in a graduated scale, and participants must judge the stimuli along a certainty property that goes up or down

Miss

in signal detection analysis, when an error occurs when an incoming signal is not detected

Point of subjective equality (PSE)

the setting of two stimuli at which the observer experience them as identical

Psychophysical scale

a scale on which people rate their psychological experience as function of the level of a physical stimulus

Receiver operating characteristic (ROC) curve

in signal detection theory, a plot of false alarms versus hits for any given sensitivity, indicating all possible outcomes for a given sensitivity

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

Scoville scale

a measure of our detection of the amount of an ingredient called capsaicin in chili peppers

Sensitivity

the ability to perceive a particular stimulus; it is inversely related to threshold

Sensitivity (signal detection theory)

the ease or difficulty with which an observer can distinguish signal from noise

Signal detection theory

the theory that in every sensory detection or discrimination, there is both sensory sensitivity to the stimulus and a criterion used to make a cognitive decision

Steven’s power law

a mathematical formula that describes the relationship between stimulus intensity and our perception; it allows for both response compression and response expansion

Transmagnetic stimulation (TMS)

a procedure in which a magnetic coil is used to stimulate electrically a specific region of the brain

Two point touch threshold

the minimum distance at which two touches are perceived as two touches and not one