Topic 1: Introduction Flashcards
What you see/hear/taste/smell/feel is the result of…
Nervous system activity alongside your knowledge gained from past experiences.
Focus is on the registration of physical stimuli on the sensory receptors that get transformed into information in our nervous system; “Detecting” that something is there
Sensation
Involves turning sensory input into a meaningful experience; “Interpreting” what is there
Perception
What are the seven steps in the perceptual process?
Step 1: Stimuli from the environment reaches our sensory receptors
Step 2: The distal stimuli get represented on the sensory receptors and become the proximal stimulus
Step 3: Involves the sensory receptors
Step 4: Neural processing
Step 5: Electrical activity becomes perception
Step 6: Perception leads to recognition
Step 7: Perception and (potentially) recognition lead to action
Stimulus that is “out there/distant” in the external environment
Distal stimuli (step 1)
“In proximity” to the receptors, in this case the image on the retina
Proximal stimulus
Describe the principle of representation
Our perception is based not on direct contact with the stimuli, but rather on representations of that stimuli (which is passed on into the nervous system)
Cells specialized to respond to environmental energy
Sensory receptors
What two things do sensory receptors do when they receive information from the environment?
Transduction
They can provide some immediate information about our perception
Transform environmental energy into electrical energy
Transduction
Our conscious awareness of something (not specific yet)
Perception
Ability to place an object in a category that gives it meaning
Recognition
Inability to visually recognize whole objects (perceive the parts, but can’t identify)
Visual object agnosia
Motor activities one makes in response to the stimulus
Action
Explain why the steps to perception are “dynamic and constantly changing”
As you move, the initial distal stimulus changes, constantly restarting the process
Any information that you (the perceiver) bring to a situation that can affect the perceptual process
Knowledge
Using knowledge to influence perception is an example of…
Top-down processing
—— is based solely on the stimuli information reaching the receptors
Bottom-up processing
What are the three major components of studying perception?
Stimulus
Physiology
Behaviour
The goal of perception research is to understand…
The relationships between stimuli, physiology, and behaviour
Describe the grating acuity example for the stimulus-behaviour relationship
Find the smallest width of lines for which the orientation of a black and white striped stimulus can be accurately judged.
Acuity is best for gratings that are horizontal and vertical as opposed to oblique
The stimulus-physiology relationship is often studied by…
Measuring brain activity
Describe the grating acuity example for the stimulus-physiology relationship
Presented with horizontal, vertical, and diagonal lines
Our environment is mostly verticals and horizontals, takes longer to process diagonals
Describe the example demonstrating the physiology-behaviour relationship
Decrease the intensity difference between light and dark bars until the participant can no longer detect the orientation
Ask them what the orientation is (behaviour), look at their brain activity (physiology)
Smallest stimulus level needed that can just barely be detected by a person
Absolute threshold
What are the three methods for measuring absolute threshold?
Method of limits
Method of constant stimuli
Method of adjustment
Describe the method of limits (measuring absolute threshold)
Stimuli presented on an ascending or descending scale and ask participants if they can detect it
The crossover point represents a switch from “I can perceive” and “I can’t perceive”
The stimuli are presented multiple times (in alternate order) and the mean crossover value indicates the threshold
Provide an advantage and disadvantage for the method of limits
Benefit is that it’s fast and can be found in relatively few trials
Disadvantage is that you can predict what’s next
Describe the method of constant stimuli (measure absolute threshold)
The intensities are presented in random order (many times)
Threshold = stimuli that results in detection on 50% of trials
Provide an advantage and a disadvantage for the method of constant stimuli
Advantage is that one is less likely to predict what’s next
Disadvantage is that its time-consuming (need more than a couple trials)
Describe the method of adjustment (measuring absolute threshold)
The participant adjusts the intensity of the stimuli themselves until they can just barely detect it.
Procedure is repeated multiple times, and the average threshold is taken.
Smallest difference between two stimuli that enables us to tell the difference between them
Difference threshold
Smallest amount of physical change observers notice as a perceptual change
Just noticeable-difference (JND)
Name four techniques for measuring perception when a stimulus is already above the threshold
Magnitude testing
Recognition testing
Reaction time
Phenomenological report
Participants judge and assign numerical estimates of the perceived strength of a stimulus
Magnitude estimation
Perceptual measure that indicates the magnitude of an experience
Perceived magnitude
Describe how to perform a magnitude estimation to evaluate the perceptual magnitude of a stimulus (when stimulus is above the threshold)
A “standard” stimulus (usually of moderate intensity) is initially given a score
Then ask participants to assign a value in proportion to the original score (perceived magnitude)
Often used to study perceptual difficulties in those with brain injuries (e.g. visual agnosia)
Recognition testing
Describe a recognition testing experiment and its typical outcome
How rapidly can you identify perceptual details when only given a short time?
Often successfully recognize the general features of rapidly presented stimuli but take much longer to recognize smaller details
Time between presentation of a stimulus and a person’s reaction to it
Reaction time
Give an example of a reaction time procedure and the expected outcome
Areas of screen labelled with different letters
Hit space when you see the x
Fixate on the + and pay attention to area A - how does reaction time compare if the dot appears in area A vs area B?
Longer reaction times when the dot doesn’t appear in the expected area
Describe phenomenological reports
“Look around you now. Describe what you see.”
Goes beyond just objective, quantifiable numbers
A more qualitative research method that helps us explain to someone what we perceive
