Exam 2: Chapter 2 Flashcards
The Scoville scale
is a psychophysical scale that measures our experience of piquancy or “hotness”. The more capsaicin is present in a particular food, the spicier it will taste.
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 experiences as a function of the level of a physical stimulus.
Scales are used to match changes in the physical amount of a stimulus with corresponding psychological changes in perception of the stimulus. Most often not linear.
exceptions: lines; coldness
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.
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.
Magnitude estimation:
a psychophysical method in which participants judge and assign numerical estimates to the perceived strength of a stimulus.
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.
Catch trial:
a trial in which the stimulus is not presented – used to check a study participant’s accuracy and honesty.
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. Technique prevents the need for catch trials because the observer can’t say yes in every trial, regardless of the presence of a stimulus.
Psychophysics:
study of the mathematical relationship between magnitude changes in physical stimuli and the resulting psychological perception
Detection:
minimum intensity that we can perceive (absolute thresholds)
example) a dog can smell blood better than a human
Discrimination:
minimum change in stimulus need to separate two stimuli (difference thresholds)
(looking at the change)
Scaling:
correlation of changes in magnitude between physical stimulus and psychological experience
sensation magnitude vs stimulus intensity graph
exponent is <1: exponential increase (example: electric shock- has a survival value)
exponent =1: linear (apparent length)
exponent < 1: concave ( brightness) (I think this is similar for audio and visual)
—visian and sound are NONlinear
when take the log: the electric shock will be greatest intensity
we think the curve is like this so we can see a wieder range of stimulus
Absolute threshold:
minimum of a stimulus required for detection
-of humans- no cut off point
look @ 50% mark for where can detect stimulus – finding the middle range
differing values for the threshold indicate that humans have top-down processing
see graph- be able to find on graph
can find experimentally through the method of descending limits: ex) making each light dimmer
—–method of limits
or methods of constant stimuli
theoretical threshold
stepwise- what a machine would give (ideal)
The method of limits
The participant must decide if a stimulus is present at a number of different levels of intensity. The stimulus is increased in even trials and decreased in odd trials. A Y indicates that the participant detects the stimulus, whereas an N indicates that the participant does not detect the stimulus.
The estimate of the threshold is considered to be the mean crossover point.
Threshold = mean crossover = 4.5
Average result of ascending and descending trails for absolute threshold
Ascending and Descending trials; errors of habituation and anticipation (subject learns pattern)
Difference threshold (the JND) Ascending series and Descending series Crossover point Two-point touch threshold
Difference threshold (JND):
Just-noticeable difference (JND), or 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.
start with canNOT see the light, until they can
note: will get slightly different answers between ascending and descending series
Descending series:
a series in which a stimulus gets increasingly smaller along a physical dimension.
start with a bright light and lower intensity
problem: can figure out the pattern; decreasing at a regular rate
note: will get slightly different answers between ascending and descending series
Crossover point:
the point at which a person changes from detecting to not detecting a stimulus or vice 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 way to measure absolute threshold
range of detectable and undetectable stimuli presented in random order
RANDOM stimuli - taking away the predictability
(this is different than the method of limits)
Fewer errors due to random procedure
Time consuming and subject may experience fatigue or boredom- try to reduce stimulus range to those values just around the threshold
—can reduce this by giving the participants a break
The threshold is the stimulus magnitude that the subject detected 50% of the time for that particular magnitude. The threshold is the value with 50% Yes and 50% No responses.
In this example, the light intensity value of 180 was detected 50% of the time when a value of 180 was presented to the subject. The value of 200 always produced a Yes response while 150 never got a Yes response.
The findings of absolute thresholds supports _________
top-down processing. A machine would have the same ‘cut-off’ regardless of direction and would give a graph like (a). But humans give a graph like (b).
FIGURE 2.6 Measuring Threshold
These graphs illustrate how we measure the threshold in psychophysical experiments. In Figure 2.6a, we see a hypothetical cutoff at a particular level of intensity that separates the stimulus level at which we see the stimulus and the stimulus level at which we do not see the stimulus. Figure 2.6b illustrates that in most cases, thresholds vary from trial to trial, and we must estimate the threshold from the point at which participants are 50% likely to say “saw it” and 50% likely to say “didn’t see it.”
Method of adjustment
! aka the staircase method: stimulus is presented and subjects response determines if next stimulus value is greater or lesser in magnitude (adaptive: Method of Adjustment)
-Observer controls the level of the stimulus: determines next stimulus value; subjects own response determines what we do next
(if starting with being able to see it, increase it when the subject cannot see it)
Best for testing adaptation to a stimulus over time (effects of alcohol on recognizing a brake light; temperature)
-Point of subjective equality (PSE): the settings of two stimuli at which the observer experiences them as identical (Two stimuli experienced as identical)
Sensitivity : Lower threshold–higher sensitivity
thresholds
Think about thresholds as if it were the threshold to a room. If you do not cross threshold then you have not entered the room (no perceptual experience). But once you cross threshold, you have entered the room (you have a perceptual experience).
unaware to aware
absolute thresholds: common examples Vision: Audition: Gustation: Olfaction: Tactile:
Vision: candle flame on clear night from 30 miles
Audition: watch ticking from 20 ft. in quite room
Gustation: 1 teaspoon of sugar in 2 gallons water
Olfaction: 1 drop perfume in 3 bedroom apartment
Tactile: Bee wing dropped one inch from skin of arm
if you are aware that your are going to be touched, or where you are touched on the arm: this can influence
absolute threshold affected by:
- humans have a lot of top-down processing
Sensitization and Habituatio: getting use to it
Cognitive penetration
Attention: example- if you are blind for the day then change in attention
people who shoot guns: the testing threshold; not as sensitive
subliminal perception
Disney is often mentioned regarding subliminal messages. You can use Google if you would like to see examples.
Is it real or just coincidence?
if it was real we would use it in education
Magnitude Estimation
Participants judge and assign numerical estimates to the perceived strength of a stimulus
a psychophysical method in which participants judge and assign numerical estimates to the perceived strength of a stimulus.
-Response compression
-Response expansion
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.
In response compression, as the physical intensity of a stimulus increase, its perceptual correlate increases as well, but not by as much.
Response expansion:
as the strength of a stimulus increases, the perceptual response increases even more.
In response expansion, as the physical intensity of a stimulus increases, its perceptual correlate increases by even more so.
The curve for brightness illustrates response ______ , whereas the curve for electric shock illustrates response __________.
The curve for brightness illustrates response compression, whereas the curve for electric shock illustrates response expansion.
Magnitude Estimation gives us
Scaling
Prothetic continuum:
changes in stimulus result in more/less of same aspect (quantity: loudness, brightness, more sugar in a solution)
quantity
example: proathletes play at college level first
Metathetic continuum:
changes in stimulus result in different experiences (quality: color of object, sweet vs. salt)
ex) different frequencies of light
Can be mixture: Metathetic continuum and Prothetic continuum
example:
touch is prothetic if testing same area, but metathetic if testing different areas
scaling 2 ways (which is used now?)
Indirect: subject asked to distinguish between two stimuli (used by Weber, Fechner)
Direct: subject asked to give value in estimating the magnitude (used by Stevens) and called magnitude estimation
Psychologist once used indirect scaling but now use direct scaling
Magnitude Estimation
Stevens’ power law
Stevens’ power law: a mathematical formula that describes the relationship between stimulus intensity and our perception; it allows for both response compression and expansion.
P = cIb P = perceived magnitude of a stimulus I = intensity of the actual stimulus c = constant
- perception of apparent length (sense= vision): exponent=1 (apparent length have 1:1 processing)
- cold testing on arm= 1:1 processing (raising exponent = 1 )
- perception of brightness (sense= vision): exponent= .3 (less than 1) (thus we are not psychologically overwhelmed by high or low levels
- perception of pain (sense= touch): exponent =3.5 (psychologically wil be more quickly, even a small change will result in big psychological difference)
- perception of sweetness (sense=taste): exponent=.8
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.
Catch Trials and Their Use
Problem of false reporting (2)
- to ensure paying attention
- can also be seen in surveys
Catch trial
Forced-choice method
Criterion -
value which decides decision making and can be low or high
-what is adjusted for the particular situation
Criterion: an internal cutoff, determined by the observer, above which the observer makes one response and below which the observer makes another response.
(Signal Detection Theory)
d′
- sensitivity of subject in judging criterion
- indicator and sensitivity
d¢ (d-prime): a mathematical measure of sensitivity.
there are individual differences: different subjects have different d’
example: muscians have better JND but same hearing ability
see graphs:
d’=0: no sensitivity; distributions that overlap: canNOT tell the difference between the 2
d’=1: moderate sensitivity
d’=4: high sensitivity (almost always can tell the stimuli apart)
(example: a noise from a road or a car)
–also professor has a problem with this being a normal curve
Receiver-operating characteristic (ROC) curve –
curve of decisions over a wide range of stimulus values; when the subject is correct or incorrect
The ROC curve is a graphical plot of how often false alarms occur versus how often hits occur for any level of sensitivity.
In signal detection theory, a plot of false alarms versus hits for any given sensitivity, indicating all possible outcomes for a given sensitivity.
Criterion (see graph)
-straight diagonal: chance diagonal= if overlap: cannot tell the difference between the two subjects
Notice the subject’s judgement curve is not linear. This reflects that the subject can discriminate the stimulus. The better the discrimination, the further away from linear the subject’s curve gets. A d’ of 2 indicates better discrimination that a d’ of 0.75. A linear diagonal represents chance discrimination that would happen with guessing.
When d′ = 0, sensitivity is zero, and the perceiver cannot discriminate between signal and noise. As d′ increases, hits and correct rejections increase, and misses and false alarms decrease. If d′ were perfect, we would get only hits and correct rejections, but in the real world, d′ is never perfect.
-in a perfect world want no overlap in d’ (a bigger d’): always able to tell stimulus apart
based on an individual (unique to a person)
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.
has to do with attention : discriminating a signal
False alarm: In signal detection analysis, a false alarm is an error that occurs when a nonsignal is mistaken for a target signal.
Miss: In signal detection analysis, a miss is an error that occurs when an incoming signal is not detected.
Correct rejection: In signal detection analysis, a correct rejection occurs when a nonsignal is dismissed as not present.
Hit: In signal detection analysis, a hit occurs when a signal is detected when the signal is present.
When we think we hear a noise associated with an engine malfunction, we adopt different criteria, depending on the situation. If we are driving the old clunker (a), we may adopt a more liberal criterion for hearing an engine problem. This will help us catch engine trouble (hits) but may also increase the rate of bringing the car to the shop when there is no problem (false alarm). If we are driving the shiny new sports car (b), we may adopt a more conservative criterion for hearing an engine problem. This will increase the likelihood of correctly dismissing a sound as noise rather than a mechanical problem (correct rejection), but may increase the likelihood that we do not hear a problem when there is one (miss).
Sensitivity
is the ability to distinguish a noise signal from an actual signal, such as the difference to distinguish random noise from the clunking sound in your car.
Masking
refers to the difficulty in seeing one stimulus when it’s quickly replaced by a second that occupies the same or adjacent spatial locations
The presence of odors influences performance on the visual task (Robinson et al., 2016)
Mint leaf
Orange
Rose
Men: no effect of odor on the masking variable
Women: sensitivity in females was helped by congruent odors, but sensitivity was also hurt by incongruent odors
The y-axis represents sensitivity. Lower values represent better detection of the masked stimuli. Sensitivity in females was helped by congruent odors, but sensitivity was also hurt by incongruent odors. In men, however, odor had no effect at all, either positive or negative.
(females have a lower threshold (good!) when have congruent smells)
Intersensory Perception: Masking
Priming: research shows that when thinking of a related item we can better recall a target item. Use this for exams!
Priming:
research shows that when thinking of a related item we can better recall a target item. Use this for exams!
spreading activation in the brain -> only one part active at a time
our brain is organized in a heirachy
- thinking of related things
ex) are cannaries yellow bc do canarries breath? - jogging your brain
- –would answer the color question faster
Neuroimaging:
techniques used to create detailed maps of the human brain and assign functions to particular regions.
Electroencephalography (EEG):
using electrodes to measure the electrical output of the brain by recording electric current at the scalp
numbers of neurons in the brain. The more electrodes that are placed on the scalp, the better the ability will be of the EEG to specify spatial locations in the brain.
(milllions of neurons measured)
-NOT using intracellular recordining
Magnetoencephalography (MEG):
using a magnetic sensor to detect the small magnetic fields produced by electrical activity in the brain.
Functional magnetic resonance imagery (fMRI):
magnetic fields create a three-dimensional image that can capture both the structure and function of the brain.
Magnetic Resonance Imaging (MRI)
Large magnetic fields align the oxygen molecules within our brains. Then, as blood flows into areas of the brain, the molecules’ organization is disrupted, which can be detected by sensors in the MRI machine.
fMRI (functional magnetic resonance imagery): magnetic fields create a three-dimensional image that can capture both the structure and function of the brain.
Transmagnetic stimulation (TMS):
a magnetic coil is used to stimulate electrically a specific region of the brain.
TMS techniques stimulate the brain via electric current. Researchers can see if perception or behavior changes in a particular domain as a function of that stimulation, allowing researchers to draw causal relations between that brain region and perception.
TMS (transmagnetic stimulation): a magnetic coil is used to stimulate electrically a specific region of the brain.
“zap” the brain
Hearing tests
-like a vision test, it will be adjusted with age
Optometrist:
Optometrist: a trained professional who specializes in diagnosing visual impairments and diseases.
Audiologists
Audiologists are trained to treat hearing loss. They assess hearing loss and help fit people with hearing aids. If medical issues arise, they will forward patients to medical doctors who specialize in auditory issues.
Audiometer
- A device for assessing hearing loss at various frequencies
- Method of Constant Stimuli
Audiogram
A graph that illustrates the thresholds for the frequencies as measured by the audiometer is known as an:
will show the: lowering of sensitivity for different frequencies in each ear
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.
Sensorineural hearing loss
hearing loss is 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 is known as:
