Perception Flashcards
1
Q
4 types of sensation:
A
Light, chemicals, mechanical forces (pressure), temperature.
2
Q
Stimuli from the physical world:
A
Distal stimuli.
3
Q
Stimuli from the mental world:
A
Proximal stimuli.
4
Q
Philosophy stating that knowledge that comes from outside the mind, that our environment shapes us.
A
Empiricism.
5
Q
Philosophy stating that certain fundamental principles shape knowledge, that we shape ourselves.
A
Rationalism.
6
Q
What transforms physical information into neural signals?
A
Receptors.
7
Q
4 types of receptors in humans:
A
Photoreceptors, mechanoreceptors, chemoreceptors, thermoreceptors.
8
Q
What is light?
A
Electromagnetic radiation.
9
Q
What do lightwaves contain?
A
Information about surfaces.
10
Q
What happens when light hits a photopigment?
A
It splits, activating the photoreceptor cell, which is called the “moment of transduction” from lightwave to neural impulse.
11
Q
What is the cause for dark adaptation?
A
Photopigment depletion.
12
Q
Why does the pupil constrict and widen?
A
To control the amount of light coming in, optimising sensitivity of the photoreceptors for the light conditions.
13
Q
Where do photoreceptors exist?
A
At the back of the eye.
14
Q
Why do photoreceptors exist at the back of the eye?
A
So that photopigments can be readily replenished.
15
Q
2 types of photoreceptors:
A
Rods and cones.
16
Q
Rods:
A
Highly sensitive but not very accurate. Slow response, peripheral and low-light achromatic vision, one type of rod, 120 million.
17
Q
Cones:
A
Highly accurate but not very sensitive. Rapid response, detailed, central, chromatic vision, 3 types of cones (short/b, medium/g, long/r), 6 million.
18
Q
Colour blindness:
A
Most commonly lose red/green differentiation, common in caucasian males.
19
Q
Where are cones concentrated?
A
On the fovea.
20
Q
Where are rods on the retina?
A
Fewer in the periphery, increase towards the fovea, but none at the fovea.
21
Q
What are eye movements good for?
A
Bringing new objects of interest to the fovea, keeps eyes fixed and stable when head and body move, prevent images from fading by shifting their position on the fovea.
22
Q
Why do we have a blindspot?
A
Because the eye needs a place where the axons of 1.2 million retinal ganglion cells come together to form the optic nerve. You can’t have any photoreceptors there.
23
Q
Why are edges important?
A
They signal the presence of an object or boundary, and the visual system exaggerates edges.
24
Q
2 retinal mechanisms for edge enhancement:
A
Lateral inhibition, center-surround retinal ganglion cells.
25
Lateral inhibition:
Disables the spreading of action potentials from excited neurons to neighboring neurons in the lateral direction. This creates a contrast in stimulation that allows increased sensory perception.
26
Center-surround retinal ganglion cells.
????
27
Receptive field:
The place/type of stimulus that elicits a response in a given neuron.
28
How do neurons respond to the stimulus?
They respond selectively to specific regions/stimuli, from sensory receptors all the way through to cortical brain areas. Respond = change firing rate (increase/decrease).
29
Mapping the receptive field. Easy or difficult?
Easier at the early stages, more difficult the further you go into the visual system.
30
2 types of retinal ganglion cells:
Midget cells, parasol cells.
31
Midget cells:
Receive input from cones, smaller number of cells, project to the parvocellular pathway (high acuity color pathway to the brain)
32
Parasol cells:
Receive input from rods, large number of cells, project to the magnocellular pathway (low acuity but highly sensitive pathway to the brain, low light, peripheral vision)
33
What's color?
Differences in the pattern of cone activation to different wavelengths of energy. Cone/rod distribution determine the experience of central/peripheral vision. Edges are exaggerated.
34
Mechanoreceptors:
Sense mechanical pressure. Physically deforming a mechanoreceptor causes ion channels to open, which causes the cell to fire.
35
3 classes of mechanoreceptors:
Inner ear, skin, muscles & tendons
36
Movement of hair cells in the inner ear:
Hearing, inertia, gravity.
37
Pressure and stretch receptors in the skin:
Light touch, texture, stretch, pain.
38
What's sound?
A (sine) wave of moving air, the amount of pressure over a certain period of time.
39
The frequency of sound.
High frequency, high-pitched/low frequency, low-pitched.
40
The amplitude of sound.
High amplitude, loud sound, low amplitude, soft sound.
41
Auditory hair cells:
Ion channels on adjacent hairs are connected by a 'tip link.' Movement of the hair cells pulls the ion channels open, depolarizing (activating) the cell.
42
Mechanoreceptors in the cochlea provide:
Loudness, pitch, timbre, NOT location (that's time and volume differences).
43
The liquid in the semicircular canals.
Endolymph. Viscosity can change which will interfere with perception.
44
What do the inner ears contain?
Otolith organs. (sense of gravity)
45
Mechanoreceptors in the skin.
Light touch, firm pressure, vibration, pain & skin stretch. All are specialised for different types of pressure.
46
Haptic touch.
Exploring objects with your subcutaneous mechanoreceptors.
47
Proprioception, kinesthesis, interoception.
Body position, movements, state.
48
Where are chemoreceptors found?
Tongue, nasal epithelium, lungs, stomach.
49
What are the papillae and what does it contain?
Part of the tongue, contains multiple taste buds.
50
What does each taste bud contain?
Multiple chemoreceptors.
51
Five known chemoreceptor types.
Salty, sweet, bitter, sour & umami (savoury).
52
Ageusia.
Inability to taste. Usually caused by nerve damage or deformity.
53
How do odorants get processed?
They bind to proteins n the cilia of the receptor cells and activate the cells. Each cell only has a single receptor type.
54
Orthonasal vs. Retronasal
Differences in perception/recognition.
55
Pheromones.
Odorants that communicate and control conspecific behaviour.
56
Anosmia.
Loss of sense of smell.
57
Four types of thermoreceptors.
Fast cold, fast hot, slow cold, slow hot.
58
Thermoreceptors are found in:
The skin, the cornea (trigger blinking), the brainstem (to regulate core temp).
59
Unmyelinated C-fibers in the skin:
Myelin speeds up neural transmission, so unmyelinated nerves are slow (taking several seconds to get to the brain)
60
A-delta fibres:
Fast, extreme heat/cold. No adaptation.
61
Where does all the input from audition, vision and touch go?
They go through the thalamus first, then to specialised areas in the cerebral cortex.
62
Primary visual pathway:
Optic nerve, optic chiasm, lateral geniculate nucleus (LGN) in the thalamus, optic radiations, primary visual cortex.
63
Where do the axons of retinal ganglion cells end up?
In the lateral geniculate nucleus (LGN) of the thalamus.
64
Parvocellular cells:
Receive input primarily from cones/midget cells. Pathway for high-acuity vision and colour.
65
Magnocellular cells:
Receive input primarily from rods/parasol cells. Pathway for detecting contrast and motion, low-light vision.
66
LGN has layers with primarily two different types of cells:
Parvocellular and magnocellular cells.
67
What are the maps of the primary visual cortex called?
The retinotopic maps.
68
What does the primary visual cortex contain?
Multiple detailed maps of visual space organised into layers.
69
What corresponds to the primary visual cortex?
The receptive fields. Each point in the receptive field corresponds to a tiny part of the primary visual cortex.
70
Blindsight:
Being able to accurately guess about stimuli presented in someone's blind field, when that part of the primary visual cortex is damaged.
71
The four components of the primary auditory pathway:
Superior olive (pons), Inferior colliculus (midbrain), Medial geniculate nucleus (MGN) in the thalamus, auditory cortex.
72
Superior olive:
Receives input from both ears, critical for detecting interaural time and volume differences, giving information about the location of sounds.
73
Inferior colliculus:
Primarily receives auditory input, also receives somatosensory and visual input. Multisensory integration occurs here. Auditory input is influenced by other modalities before it reaches the cortex.
74
The medial geniculate nucleus (MGN):
Right next to the lateral geniculate nucleus. Like the LGN, acts as a relay station on the way to primary auditory cortex.
75
Primary auditory cortex:
Contains a tonotopic map of all frequencies (pitches), and selectivity for location, timing, and amplitude.
76
What does damage do to the primary auditory cortex?
Damage leads to an analogous condition to blindsight: inability to consciously identify certain tones, but guessing is above chance.
77
Auditory deprivation: tinnitus.
Can be a tone, buzz, white noise, squeaking, clicking, crickets, music, etc. Usually results from hearing loss. 10-20% of the population. More common in elderly and males.
78
Three components of the primary somatosensory pathway:
Dorsal root ganglion, ventroposterior nucleus in the thalamus, somatosensory cortex.
79
Dorsal root ganglion:
Skin receptors are just one part of the nerve cell. The cell body is in the dorsal root ganglion, next to the spinal cord.
80
Primary somatosensory cortex:
Post central gyrus. Damage leads to lowered sensitivity to touch and an inability to identify objects by touch. Damage can also lead to a sense of disownership of body parts.
81
Tactile deprivation / phantom limb:
Continued perception of a missing limb. 5-10% of amputees.
82
The process of perception:
Sample physical information, integrate and encode it in the brain, interpret and use it.
83
What is important to perceive the scene correctly?
Disambiguate the stimulus on the receptors, recognise hidden/blurred objects, from different viewpoints, across different sizes or scales.
84
How do we perceive the scene correctly?
Looking at objects/scenes from different viewpoints using experience, context and previous knowledge we have about objects and scenes.
85
Object recognition in structuralism:
Perceptions are created by combining elements called sensations.
86
Object recognition in Gestalt psychology:
The whole differs and is greater than the sum of its parts. Perception is a result of perceptual organisation.
87
Principles of perceptual organisation:
Simplicity, Similarity, Good Continuation, Proximity, Common Region, Connectedness, Synchrony, Common Fate, Familiarity.
88
Law of Simplicity:
Reality is organised to the simplest form possible.
89
Perceptual segregation:
Seeing two different things in one image.
90
Componential recovery:
We can identify an object rapidly if we can identify its individual geons.
91
View-invariance:
Can be identified when viewed from different angles.
92
Geons:
Basic shapes. There are 36.
93
Non-accidental properties:
Properties that do not change with orientation in depth.
94
View-point dependent recognition:
Object recognition is affected by the viewpoint, objects seen in less familiar viewpoints are less well recognised.
95
Face recognition is important for:
Identification, Communication, Emotions, Gender
96
Acquired prosopagnosia:
Lesions in right occipital, temporal or fusiform brain regions.
97
Developmental prosopagnosia:
Lifelong deficit that manifests itself in early childhood and cannot be attributed to brain damage.
98
Capgras syndrome:
A disorder in which a person holds a delusion that a friend, spouse, parent, or other close family member has been replaced by an identical-looking impostor.
99
Divided attention:
Paying attention to more than one thing at a time. There's a single pool of attentional resources that can be freely divided between tasks.
100
Selective attention:
Paying attention to one thing at a time.
101
Saccades:
Small, rapid eye movements.
102
Fixations:
Pauses in eye movements that indicate where a person is attending.
103
How many fixations per second?
Approx. 3.
104
Why is selective attention necessary?
It is efficient, there is too much incoming stimulation to process everything.
105
What determines how we scan a scene?
Stimulus salience (color, orientation, contrast), knowledge about scenes, nature of the observer's task, learning from past experience.
106
Inattentional blindness:
Failure to notice an unexpected stimulus that is in one's field of vision when one performs other attention-demanding tasks. Not a visual but an attentional blindness.
107
Change blindness:
When a large change within a visual scene is undetected by the viewer.
108
Akinetopsia:
Motion blindness.
109
Electrical stimulation in MT causes:
Changes in motion perception.
110
Neuronal adaptation:
Neurons coding a particular movement reduce their responses with time of exposure to a constantly moving stimulus.
111
Aperture problem:
Observation of a small portion of a moving object makes it difficult to perceive in what way the object is moving.
112
Corollary discharge theory:
A copy of a motor command that is sent to the muscles to produce a movement. This copy or corollary does not produce any movement itself but instead is directed to other regions of the brain to inform them of the impending movement.
113
Peripheral drift illusion:
The image that moves in your periphery when you focus on the middle.
114
Proprioception:
The sense of the relative position of the body parts.
115
Vestibular ocular reflex:
Movement of the eyes to compensate rotation of the head.
