Sensory Methods and Signal Detection Theory Flashcards
Psychophysical measure of olfaction
Odour identification and odour naming
Odour detection
Intensity differentiation
method of adjustment
Participant adjusts the stimulus until detectable based on criterion
Method of limits
Stimulus intensity is presented in increased or decreased thresholds
Method of constant stimuli
Random presentation of stimuli at various intensities.
- reduces bias
name the four sensory differences tests
yes/no
2n alternative forced choice task
3n alternative forced choice task
same/different task
yes/no test
Identifying the presence or absence of a stimulus.
2-alternative forced choice task
Choosing between two presented options
3-alternative forced choice task
Choosing between three presented options.
Same/different task
Identifying if two stimuli are the same or different.
relationship between normal distribution and perception
Perceptual strength of the same stimulus follows a normal distribution.
percentage correct
correct trials/trials
- follows an S Curve
normal distribution criterion
set halfway between chance and perfect performance
signal detection theory and decision making
- Used to quantify how people make decisions under uncertainty
- Distinguished between an observer’s sensitivity to a stimulus and their decision making criteria
what are the two things that SDT measures
sensitivity and decision making
what is signal and noise
Signal: Relevant information being detected.
Noise: Irrelevant background information.
what is D’ (d prime)
Sensitivity measure, the distance between two distributions.
Recognises perceptual variation, pure sensitivity measure, measures response bias.
what do the two curves in the normal distribution represent
noise (no signal present)
signal (signal present)
what are the four possible outcomes of SDT
Hit: Correctly detecting a signal when it’s present.
Miss: Failing to detect a signal when it’s present.
False Alarm: Mistakenly detecting a signal when only noise is present.
Correct rejection: Correctly identifying that no signal is present.
What happens when the decision threshold is moved to the right
Fewer false alarms
More misses
What happens when the decision threshold is moved to the left
Fewer misses
More false alarms ⬆️
Cross modal sensory interactions
Where one function of one sense is changed by stimulation of another sense
e.g
- odour and taste
- audio and speech
McGurk Effect
Audiovisual speech perception
baa baa baa vs faa faa faa
Below threshold tastant + below threshold odorant
above threshold flavour
e.g vanilla and sucrose
factors influencing sensory interactions
previous experience: Familiar pairings enhance perception.
familiarity: Stronger effects with known combinations.
congruency: Stronger enhancement when taste and odour match.
how does colour influence taste
brighter food seems more intense in flavour vs dull food
Blackwell (1955) Juice example
orange juice, blackberry juice
- changed colours to see if people could still identify what they were
- found that the colour was rather important for identification
Synaesthesia
Perceptual phenomenon in which stimulation of one sensory or cognitive pathway leads to involuntary experiences in a second sensory or cognitive pathways
- E.g pairing colours and numbers
not cross modal
- Temperature: could change physical elements of stimulus so could be introducing new sensation
- Viscosity: changing the availability of molecules e.g spread
- Fat content: influence physical property of food, so will change its flavour
thermal taster
Thermally induced taste sensations may be elicited when the tongue is thermally stimulated in the absence of gustatory stimulus
- About 25% of the population have this
