Chapter 1: Introduction to Perception Flashcards
Perception
Conscious experience that results from stimulation of the senses
Perceptual Process (Super basic, figure 1.1)
1) Stimulus in the environment
2) Light is reflected and focussed
3) Receptor Processes
4) Neural Processing
5) Perception
6) Recognition
7) Action
Sensation
Often identified as involving simple “elementary: processes that occur right at the beginning of a sensory system (detecting elementary properties of a stimulus)
-rather rare to use / see (taste receptors)
Perception
Identified with complex processes that involve higher-order mechanisms such as interpretation and memory that involve activity in the brain (Involves higher brain functions involved in interpreting events and objects)
-extremely common to see
Perceptual Process Step 1
Distal Stimulus (The object we observe, i.e a tree) -The persons perception of the tree is based on light reflected from the tree and reaching the visual receptors
Principle of transformation
States that stimuli and responses created by stimuli are transformed, or changed, between the distal stimulus and perception
Proximal Stimulus (Step 2)
The image on the retina (if the eye’s optics -the way the light enters the eye through the cornea and lens- are not working right, the image may be blurry
Principle of representation
States that everything a person perceives is based not on direct contact with stimuli but on representation of stimuli that are formed on the receptors and the resulting activity in the person’s nervous system
Sensory receptors (Step 3 between slides 9-13)
Cells specialized to respond to environmental energy, with each sensory system receptors specialized to respond to a specific type of energy
When visual receptors that line the back of the eye receive the light reflected from the tree, 2 things happen
1) they transform the environmental energy into electrical energy
2) the shape perception by the way they respond to different properties of stimuli
Visual receptors transform light energy into electrical energy because they contain a light-sensitive chemical called?
Visual pigament
Transduction
The transformation of one from of energy to another form
Visual pigment shape perception in two ways
1) The ability to see dim light depends on having a high concentration of light sensitive pigment in the receptors
2) There are different types of pigments, which respond best to light in different parts of the visible spectrum
Interconnected network of neurons that
1) Transmit signals from the receptors, through the retina, to the brain, and then within the brain
2) change (or process) these signals as they are transmitted
Step 4
Neural processing involves interactions between the electrical signals travelling in networks of neurons early in the system, in the retina; later, on the pathway to the brain, an finally, within the brain
Neural processing
The changes in these signals that occur as they are transmitted through this maze of neurons
Electrical signals for each sense arrive at the primary recieving are for that sense in the ___ of the brain
Cerebral cortex
Cerebral cortex
A 2mm thick layer that contains the machinery for creating perceptions, as well as other functions such as language, memory, and thinking
Occipital Lobe
The primary receiving area for vision occupies most of the occipital lobe
Temporal Lobe
The primary receiving area for hearing
Parietal lobe
The primary receiving area for skin senses-touch, temperature, and pain
Frontal lobe
Receives signals from all of the senses, and plays an important role in perceptions that involve the coordination of information received through two or more senses
Behavioural responses (Steps 5-7) (Cards 23-
After all that reflection, focussing, transduction, transmission, and processing, we reach the behavioural responses
This step is the most miraculous as electrical signals (step 4) are transformed into conscious experience. The person perceives the tree (Step 5) and recognizes it (step 6)
Perception in this case
conscious awareness of the tree (I see something)
Recognition in this case
Placing an object into category, such as “tree” (It is an oak tree)
Visual form agnosia
an inability to recognize objects
Action (step 7)
Involves motor activities (walk towards the tree)
Knowledge
Any information that the perceiver brings to a situation
Rat-man demonstration
Shows how recently acquired knowledge can influence perception
Bottom-up processing (data based processing)
Processing that is based on the stimuli reaching the receptors (this is the starting point as perception involves the activation of the receptors)
Top -down Processing (knowledge based processing)
Processing based on knowledge (When a women labels what she is seeing as a moth she accessing what she has learned about moths)
3 Relationships in the Perceptual Process
Relationship A: The stimulus-perception relationship
Relationship B: The stimulus-physiological relationship
Relationship C: The physiology-perception relationship
Oblique effect
People see vertical or horizontal lines better than lines orientated obliquely (any orientation other than vertical or horizontal) (Ferrets brains response better to straight and sideways line opposed to diagonal)
Stimulus-perception relationship
Relates stimuli to behavioural responses
Grating acuity
The smallest width of lines that a subject can detect
The stimulus-physiological relationship
Relationship between stimuli and physiological
Physiology-perception relationship
relates physiological responses and behavioural responses (subjects were able to see 90 degree and 0 degree lines at lower brightness)
Cognitive influence on perception
Researchers study cognitive influences by measuring how knowledge and other factors, such as memories and expectations, affect all of the relationships
Thresholds
Measure the limits of sensory systems, they are measure of minimums- the smallest line width can be detected, the smallest amount of of sound energy we can hear, smallest concentration of a chemical we can taste or smell
Gustuv Fechner (1801-1887)
Proposed the idea that the mind could be studied by measuring the relationship between changes in the physical stimulation (the body part of the relationship) and a person’s experience (the mind part)
E.G. Turn up brightness of light, increase perception
Psychophysics
The study of the relation between mental (psycho) and physical (physics)
Method of limits
Experimenter presents stimuli in either ascending order (intensity is increased) or descending order (intensity is decreased) (average results)
Absolute threshold
Smallest stimulus level that can just be detected
Difference Threshold
Smallest different between two stimuli that enables us to tell the difference between them
Dark adaption curve
Shows how the threshold becomes smaller as the person spends more time in the dark
What is the perceptual magnitude of a stimulus?
Technique: Magnitude Estimation
testing the difference between overpowering and faint, or loud and whisper
Magnitude Estimation Example
Showing someone a light of moderate intensity and calling it a 10. Now, changing that light brightness and asking for a new number. The number for “brightness’ is the perceived magnitude of the stimulus
What is the identity of the stimulus?
Technique: Recognition Testing (the process of categorizing)
How quickly can I react to it
Technique: Reaction Time
Reaction time
The time between presentation of a stimulus and the person’s reaction to it
How can I demonstrate what is out there?
Technique: Phenomenological report
Phenomenological report
Describing what is out there (Same or different colours, size, pattern of lights, etc)
How can i interact with it?
Technique: Physical tasks and judgement
Physical vs perceptual
a) shining a light in someone eye at brightness 10
b) shining the light of 2 bulbs in someones eye, totalling 20
Both a and b are physical right now, to figure out the perception we need to use a test such as the Magnitude estimation
indirect Approach / constructive
Nervous system processes perceptions, makes them up. When the nervous system makes up the wrong thing that when we get illusions
Method of adjustment
The subject adjusts the stimulus intensity continuously until they can barely detect the stimulus (turn a knob until you cant hear sound)
Method of constant stimuli
Experimenter presents 5-9 stimuli with different intensities in a random order (person says yes or no if they can hear, see, etc the stimuli) (most accurate test to do given the quantity of tests and the randomness)
Response compression
The increase in perceived magnitude is smaller than the increase in stimulus intensity
Response expansion
As intensity is increased, perceptual magnitude increases more then intensity
Weber fraction
The ratio standard for lifting weights is 0.02
Weber law
The fact that the weber fraction remains the same as the standard is changed
Response criterion
A way to describe the difference between two people
False alarm
Person has detected a signal when one was not sent
