Chapter 6: Sensation and Perception Flashcards
1
Q
What is sensation?
A
The process by which our sensory receptors and nervous system receive and represent stimulus energies from our environment…
aka the information the nervous system transmits to the brain.
2
Q
What is perception?
A
The processes by which one’s brain organizes and interprets sensory input, enabling us to recognize meaningful objects and events.
3
Q
In our everyday experiences, sensation and perception…
A
Blend into one continuous process.
4
Q
What is bottom-up processing?
A
Starts at the sensory receptors, works up to higher levels of processing.
Sensory –> Integration of sensory information
5
Q
What is top-down processing?
A
Constructs perceptions from the sensory input by drawing on our experience and expectations.
Processing guided by higher-level mental processes.
6
Q
What three steps are basic to all our sensory systems?
A
- RECEIVE sensory stimulation –> Specialized receptor cells
- TRANSFORM stimulation –> Neural impulses
- DELIVER the neural information to our brain
7
Q
What is transduction?
A
The process of converting one form of energy into another that our brain can use.
8
Q
What is psychophysics?
A
The study of the relationships between the physical energy we can detect and its effects on our psychological experiences.
9
Q
What are absolute thresholds?
A
The minimum stimulation necessary to detect a particular stimulus 50% of the time
=Half the time, you can detect, half the time, you cannot detect.
10
Q
What is signal detection theory?
A
Prediction of how/when we will detect weak signals in the presence of background stimulation, as detecting weak stimulus depends on both strength and psychological state - experience, expectations, motivations, stress.
Why do people respond differently to the same stimuli? Why do reactions vary as circumstances change?
11
Q
What are subliminal stimuli?
A
Stimuli you cannot detect 50% of the time - below your absolute threshold for conscious awareness.
12
Q
What is priming?
A
The activation, often unconsciously, of certain associations, thus predisposing one’s perception, memory, or response.
13
Q
When can we evaluate a stimulus?
A
Even when we aren’t aware of it, and unaware of our evaluation.
14
Q
What is the dual-track mind, in terms of sensation and perception?
A
Much of our information processing occurs automatically, out of sight, off the radar screen of our conscious mind.
15
Q
What is the difference threshold?
A
The minimum difference between two stimuli required for detection 50% of the time. We experience the difference threshold as a ‘just noticeable difference’.
16
Q
The difference threshold _________ with the size of the stimulus.
A
Increases
17
Q
Does subliminal sensation enable subliminal persuasion?
A
Subliminal = Below consciousness
Though subliminal sensation can subtly influence people, they don’t have a powerful, enduring effect.
18
Q
What is Weber’s law?
A
For an average person to perceive a difference, two stimuli must differ by a constant minimum PERCENTAGE, no a constant amount.
The proportion varies depending on the stimulus.
19
Q
What is sensory adaptation?
A
When constantly exposed to an unchanging stimulus, we become less aware of it – our nerve cells fire less frequently = Less sensitive
20
Q
How does the sensory adaptation not apply to vision?
A
Our eyes are always moving, whether we are aware of it or not! This ensures that the stimulation on the eyes’ receptors continually changes.
21
Q
What is the pro to sensory adaptation?
A
It allows us to focus on informative changes in our environment, without being distracted by background chatter –> USEFULNESS
22
Q
What is a perceptual set?
A
A set of mental tendencies and assumptions that affect, top-down, our sensations.
Expectations that come with experience.
23
Q
What determines our perceptual set?
A
Through experience, we form concepts/schemas that organize and interpret unfamiliar information.
24
Q
How does the immediate context affect our perception?
A
The context creates an expectation that, top-down, influences our perception.
25
How are perceptions influenced by our emotions and motivation?
Depending on how we feel and what our needs are at that moment, we perceive things differently.
This also alters our social perceptions.
26
How do we see?
Our eyes receive light energy and transduce (transform) it into neural messages that our brain processes, into what we see consciously.
27
What do we see as visible light?
A thin slice of the whole spectrum of electromagnetic energy.
28
What two physical characteristics of light help determine our sensory experience?
1. WAVELENGTH: The distance from one wave peak to the next, determining its HUE (colour we experience) and its FREQUENCY (number of complete wavelengths in a given time).
2. INTENSITY: Amount of energy in light waves, determined by the wave's amplitude, influencing BRIGHTNESS.
A great amplitude = bright colours;
A small amplitude = dull colours.
29
How does the eye work?
1. Light enters through the cornea
2. The cornea bends light to help provide focus
3. Light passes through the pupil: small adjustable opening
4. The iris surrounds the pupil and controls its size (dilates/constricts), in response to light intensity and to cognitive & emotional states
5. The lens, behind the pupil, focuses incoming light rays into an image on the retina - multilayered tissue on the eyeball's sensitive inner surface.
6. The lens focuses the rays, by changing its own curvature and thickness in a process called accommodation.
30
How come the image on the retina appears upside down and reversed?
Light rays reflected from the object pass through the cornea, pupil, lens.
The curvature and thickness of the lens change, to bring nearby/distant objects into focus on the retina.
Rays from the top of the object strike the bottom of the retina;
rays from the left side of the object strike the right side of the retina.
31
What is the pupil?
The adjustable opening in the center of the eye, through which light enters.
32
What is the iris?
A ring of muscle tissue that forms the coloured portion of the eye around the pupil and controls the size of the pupil opening.
33
What is the lens?
The transparent structure behind the pupil which changes shape to help focus images on the retina.
34
What is the retina?
The light-sensitive inner surface of the eye, containing the receptor rods & cones, plus layers of neurons that begin the processing of visual information.
35
What is accommodation?
The process by which the eye's lens changes shape, to focus near/far objects on the retina.
36
How does retinal processing work?
1. Light entering the eye triggers a chemical reaction in the rods and the cones at the back of the retina.
2. The chemical reaction activates bipolar cells.
3. Bipolar cells activate ganglion cells, whose combined axons form the optic nerve.
The optic nerve transmits information, via the thalamus, to the brain.
37
What are rods?
Retinal receptors that detect black, white, and gray. They are necessary for peripheral and twilight vision when cones don't respond.
38
What are cones?
Retinal receptor cells concentrated near the centre of the retina, and function in daylight/well-lit conditions.
The cones detect fine detail and give rise to colour sensations.
39
What is the optic nerve?
The nerve carrying neural impulses from the eye to the brain = Information highway.
The thalamus is ready to distribute the information it receives from your eyes.
40
What is the blind spot?
The point at which the optic nerve leaves the eye, creating a "blind" spot because no receptor cells are located there.
41
How do rods and cones differ in where they're found and what they do?
Cones cluster in/around the FOVEA: Retina's area of central focus.
Each cone transmits its message to a single bipolar cell = "Personal hotline" = Direct connection, preserving the cones' precise information = Better able to detect fine details.
Cones enable colour perception.
Rods share bipolar cells which send combined messages = Funnel their faint energy together.
Rods enable B/W vision, sensitive in dim light.
42
What is the Young-Helmholtz trichromatic (three-colour) theory?
The theory that the retina contains three different colour receptors, one most sensitive to red/green/blue, which, when stimulated in combination, can produce the perception of any colour.
43
What do colour-deficient people lack?
Functioning red or green-sensitive cones, or sometimes both.
44
What is the afterimage effect?
When we stare at a colour, then look at a white sheet of paper, we see its opponent colour.
45
What is Hering's opponent-process theory?
There exist three sets of opponent retinal processes, red-green, yellow-blue, white-black, which enable colour vision.
Some cells are stimulated by green, inhibited by red, and vice-versa.
46
How does colour-processing occur?
In two stages...
1. The retina's red, green, and blue cones respond in varying degrees to different colour stimuli, as the Young-Helmholtz trichromatic theory suggested.
2. The cones' responses are processed by opponent-process cells, as Hering's theory proposed.
47
What are feature detectors and where are they located?
Feature detectors are nerve cells in the brain that respond to a scene's specific features - particular edges, lines, angles, movements.
They are specialized neurons in the occipital lobe's visual cortex, which receive information from individual ganglion cells in the retina.
Feature detectors pass this information to other cortical areas, where cell teams ('supercell clusters') respond to more complex patterns.
48
What is the right temporal lobe area dedicated to in social humans?
Face recognition!
49
What is parallel processing?
The processing of many aspects of a problem simultaneously; the brain's natural mode of information processing for many functions, including vision.
50
How does the visual system illustrate the dual processing of our two-track mind?
After the damage to the brain's visual cortex, people experience BLINDSIGHT.
They report seeing nothing, but when asked to guess whether the sticks are horizontal/vertical, they offer the right response!
--> Separate visual systems for action and perception
51
How does visual information processing work?
1. Scene
2. Retinal processing: Receptor rods and cones --> Bipolar cells --> Ganglion cells
3. Feature detection: Brain's detector cells respond to specific features
4. Parallel processing: Teams of brain cells, to process information about colour, movement, form, depth
5. Recognition: Brain interprets the constructed image, based on information from stored images
52
What is the concept of a gestalt?
When given a cluster of sensations, people tend to organize them into a gestalt - our conscious perception is an integrated whole.
The whole may exceed the sum of its parts.
OUR BRAIN DOES MORE THAN REGISTER INFORMATION ABOUT THE WORLD. IT FILTERS INCOMING INFORMATION AND CONSTRUCTS PERCEPTIONS.
53
What is the figure-ground relationship?
We organize a stimulus into a figure seeing against a ground.
Our first perceptual task is to perceive any object (figure) as distinct from its surroundings (ground).
54
What is grouping?
The way in which the mind organizes the figure into a meaningful form, by creating coherent groups.
55
What are the three types of grouping we apply?
PROXIMITY: We group nearby figures together.
CONTINUITY: We perceive smooth, continuous patterns rather than discontinuous ones.
CLOSURE: We fill in gaps to create a complete, whole object.
56
What does depth perception allow us to do?
Enables us to estimate an object's distance from us.
57
What is the visual cliff experiment?
A miniature cliff with a glass-covered drop-off to determine whether crawling infants and newborn animals can perceive depth.
Even when coaxed, infants are reluctant to venture onto the glass over the cliff.
58
How do we transform two differing 2D retinal images into a single 3D perception?
BINOCULAR CUES: Depth cues, such as retinal disparity, that depend on the use of two eyes.
Because your eyes are 2 1/2 inches apart, the retinas receive slightly different images. The brain compares these images to judge how close an object is to you.
The greater the RETINAL DISPARITY (the difference between the two objects), the closer the object. The retinal disparity shrinks as the object moves away.
MONOCULAR CUES: Depth cues available to each eye separately,
59
What are the different types of monocular depth cues?
Relative height: We perceive objects higher in our field of vision as farther away.
Relative motion: As we move, objects that are actually stable may appear to move.
Relative size: If we assume two objects are similar in size, the one that casts the smaller retinal image seems farther away.
Linear perspective: Parallel lines appear to meet in the distance.
Interposition: If one object partially blocks our view of another, we perceive it as closer.
Light and shadow: Shading produces a sense of depth consistent with our assumption that light comes from above.
60
How does the brain compute motion?
Shrinking objects are retreating; enlarging objects are approaching.
When large and small objects move at the same speed, the large objects appear to move more slowly.
61
What is stroboscopic movement?
The phenomenon in which our brain perceives a rapid series of slightly varying images as continuous movement. We construct the motion in our heads!
62
What is the phi phenomenon?
An illusion of movement created when two or more adjacent lights blink on and off in quick succession.
63
What is perceptual constancy?
Perceiving objects as unchanging, thus with consistent colour, brightness, shape, and size, despite illumination and retinal images changing = Top-down process
64
Our experience of colour depends on...
The object's context --> The relative colour of the objects surrounding it.
This also applies to brightness, in which it all depends on how the object appears relative to its surroundings.
65
What is colour constancy?
Perceiving familiar objects as having consistent colour, even if changing illumination alters the wavelengths reflected by the object.
66
_________ govern our perceptions.
Comparisons!
67
What is shape constancy?
In which, though an object's actual shape cannot change, it seems to change shape with the angle of our view, but we know it is still constant.
68
What is size constancy?
In which we perceive as having a constant size, even while our distance from them varies.
**Size-distance relationships
69
What does research on restored vision, sensory restriction, and perceptual adaptation reveal about the effects of experience on perception?
Experience guides, sustains, and maintains the brain neural organization that enables our perception.
If a man born blind is made to see, he could not distinguish between a cube and a sphere, because he would never have LEARNED to see the difference.
70
What is the critical period?
An optimal period when exposure to certain stimuli or experiences is required. This is when the effect of sensory restriction plays a huge role!
Use it soon, or lose it! We retain the imprint of some early sensory experiences far into the future.
71
What is perceptual adaptation?
In vision, the ability to adjust to an artificially displaced, or even inverted visual field. We adapt to distorting lenses!
72
What are the characteristics of air pressure waves that we hear as sound?
The amplitude of sound waves determines their loudness.
```
Their length (frequency) determines the pitch we experience.
Long waves = Low frequency = Low pitch
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73
What is the unit by which we measure sounds?
Decibels!
74
How does the ear transform sound energy into neural messages?
1. Sound waves enter the outer ear.
2. The visible outer ear channels the waves through the auditory canal to the eardrum, a tight membrane, causing it to vibrate.
3. In the middle ear, a piston made of three tiny bones (hammer, anvil, stirrup) picks up the vibrations.
4. The piston transmits the vibrations to the cochlea, a snail-shaped tube in the inner ear.
5. The vibrations cause the cochlea's membrane (the oval window) to vibrate, jostling the fluid that fills the tube.
6. This causes ripples in the basilar membrane, bending the hair cells ("carpet fibers") lining its surface.
7. Hair cell movement triggers impulses in the adjacent nerve cells.
8. Axons of the nerve cells converge to form the auditory nerve.
9. The auditory nerve sends neural messages via the thalamus to the auditory cortex in the brain's temporal lobe.
75
What causes sensorineural hearing loss?
Damage to the cochlea's hair cell receptors, or their associated nerves.
76
What causes conduction hearing loss?
Damage to the mechanical system that conducts sound waves to the cochlea.
77
What is a cochlear implant?
A device for converting sounds into electrical signals and stimulating the auditory nerve through electrodes threaded into the cochlea.
78
How do we detect loudness?
The brain interprets loudness from the NUMBER of activated hair cells.
79
How do we discriminate pitch?
Place theory: Helmholtz's theory, in which we hear different pitches because different sound waves trigger activity at different places along the cochlea's basilar membrane.
The brain determines pitch by recognizing the SPECIFIC PLACE on the membrane generating the neural signal.
Frequency theory: In which the brain reads pitch by monitoring the frequency of neural impulses traveling up the auditory nerve. The whole basilar membrane vibrates with the incoming sound waves, triggering neural impulses to the brain at the same rate as the sound wave.
**Place theory best explains how we sense HIGH pitches.
**Frequency theory best explains how we sense LOW pitches.
**For pitches in the INTERMEDIATE range, some combination of place and frequency theories applies.
80
How do we locate sounds?
Thanks to the placement of our two ears, we enjoy stereophonic (3D) hearing!
Sound waves strike one ear sooner and more intensely than the other. This allows our brain to compute the sound's location!
81
How do we sense touch?
It is a mix of four basic and distinct skin senses, in the variations of...
- Pressure
- Warmth
- Cold
- Pain
82
What affects our experience of pain?
Our experience of pain reflects both BOTTOM-UP sensations, and TOP-DOWN cognitions.
83
What are nociceptors?
Different nociceptors, sensory receptors in our skin, muscles, and organs, detect hurtful temperatures, pressure, or chemicals.
The nociceptors respond to potentially damaging stimuli --> Impulse to the spinal cord --> Message to brain --> Signals as pain!
84
What is the gate-control theory?
In which the spinal cord contains a neurological "gate" that blocks pain signals or allow them to pass on to the brain.
When tissue is injured, the small fibres activate and open the gate --> you feel pain
Large-fibre activity closes the gate, blocking pain signals and preventing them from reaching the brain.
--> One way to treat chronic pain is to stimulate (massage, electric stimulation, acupuncture) "gate-closing" activity in the large neural fibres.
85
What is the phantom lib sensation?
In which the brain creates pain, even after a limb has been amputated.
86
We feel, see, hear, taste, and smell with our ________.
Brain! The brain can sense, even without functioning senses.
87
What is a powerful influence on our perception of pain?
The attention we focus on it!
We tend to edit our MEMORIES of pain - differs from the pain we actually experience.
88
When do we tend to perceive more pain?
When others seem to be experiencing pain.
89
What are the biological influences of pain?
- Activity in the spinal cord's large and small fibres
- Genetic differences in endorphin production
- Brain's interpretation of CNS activity
90
What are the psychological influences of pain?
- Attention to pain
- Learning based on experience
- Expectations
91
What are the social-cultural influences of pain?
- Presence of others
- Empathy for others' pain
- Cultural expectations
92
Our experience of pain _______ when we are distracted from pain.
This is thanks to the release of _________________.
Our experience of pain DIMINISHES when we are distracted from pain, and soothed by the release of our natural painkilling ENDORPHINS.
93
What is the relationship between placebos and pain?
Even an inert placebo can help, by dampening the central nervous system's attention and responses to painful experiences.
"Believing becomes reality".
94
How does distraction alleviate pain?
It activates pain-inhibiting circuits, and increases pain tolerance.
95
What is hypnosis?
A social interaction in which one person suggests to another that certain perceptions, feelings, thoughts, or behaviours will spontaneously occur. This can lessen pain!
96
How does hypnosis work, from a biological perspective?
It inhibits pain-related brain activity.
97
How does hypnosis work, from a social perspective?
It is a form of social influence - a by-product of normal social and mental processes.
98
What is the hypnosis theory of dissociation?
A view of hypnosis as being a special dual-processing state, a split between different levels of consciousness.
This allows some thoughts and behaviours to occur simultaneously with others.
**SELECTIVE ATTENTION!
99
What is posthypnotic suggestion?
Suggestion made during hypnosis, to be carried out after the subject is no longer hypnotized.
100
What are the survival functions of our basic tastes?
Sweet = Energy source
Salty = Sodium is essential to physical properties
Sour = Potentially toxic acid
Bitter = Potential poison
Umami = Proteins to grow and repair tissue
101
Taste is a ________ sense.
Chemical! Each taste bud pore contains taste receptor cells that project antenna-like hairs to sense food molecules.
Some receptors respond to a certain taste, while others to another.
102
How often to taste receptors reproduce themselves?
Every week or two!
103
What happens to the number of taste buds, as you grow older?
Decreases!
As such, you have less taste sensitivity.
104
Smell is a _________ sense.
Chemical!
Your olfactory receptor cells respond selectively, and alert the brain through their axon fibers.
105
True or false: Your olfactory neurons bypass the thalamus?
TRUE! These neurons bypass the brain's sensory control centre, being an old, primitive sense.
106
What affects our ability to identify scents?
- Gender
- Age
- Physical condition
+ Odor molecules come in many shapes and sizes, and requires many different receptors to detect them!
107
What distinguishes senses of sights/sounds from the sense of smell?
We can easily experience and remember sights and sounds, but smells are primitive, and harder to describe and recall.
108
What does the attractiveness of smell depend on?
Learned associations! When good experiences are linked with a particular scent, people come to like that scent.
109
How do taste, smell, and memory interact?
A "hotline" runs between our taste buds/nose to our brain!
The brain area receives this information and associates it with the brain's limbic centres associated with memory and emotion.
110
What is kinesthesia?
The system for sensing the position and the movement of individual body parts.
**For example, our vision interacts with kinaesthesia. If you were to close your eyes and stand with your right heel in front of your left toes, it's harder and you will wobble!
**The receptors are located in our tendons, joints, and muscles.
111
What is vestibular sense?
The sense of the head's (and thus body's) movement and position, including the sense of balance.
112
What are the biological gyroscopes for this sense of equilibrium (vestibular)?
Two structures in your inner ear!
1. SEMICIRCULAR CANALS: 3D pretzels
2. VESTIBULAR SACS: Pair of sacs that connect those canals with the cochlea, which contain fluid that moves when your head rotates or tilts.
113
What is sensory interaction?
The principle that one sense may influence another.
Example: Smell + texture + taste = Flavour!
114
What is the McGurk effect?
A phenomenon that occurs when the eyes and the ears disagree (we hear a speaker saying one syllable, see him say another).
As a result, we may perceive a third syllable that blends both inputs.
115
What two types of judgments does our brain blend?
Our tactile and social judgments!
116
What is embodied cognition?
In psychological science, the influence of bodily sensations, gestures, and other states on cognitive preferences and judgments.
We think from within a body!
As we attempt to decipher our world, our brain blends inputs from multiple channels.
117
How is perception a biopsychosocial phenomenon?
BIOLOGICAL INFLUENCES
- Sensory analysis
- Unlearned visual phenomena
- Critical period for sensory development
PSYCHOLOGICAL INFLUENCES
- Selective attention
- Learned schemas
- Gestalt principles
- Context effects
- Perceptual set
SOCIAL-CULTURAL INFLUENCES
-Cultural assumptions and expectations
