Sensation and Perception Flashcards
1
Q
Sensation
A
Is the process by which our sense organs and receptors detect and respond to physical stimuli that stimulates them
- a passive and automatic process
2
Q
Perception
A
Is the process of assigning meaning to raw information
- active process; brain constructs personal understanding and reality from raw sensory info
3
Q
Key Processes of Sensation and Perception
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Reception and Receptive Fields
Transduction
Transmission
Interpretation
4
Q
Reception
A
Sensory receptors receive and process sensory info
5
Q
Receptive Field
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Area of space on a receptor site where receptors can respond to stimuli
6
Q
Transduction
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Receptors change energy of sensory info into a form that can travel along neurons as action potentials
7
Q
Transmission
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Sensory info sent to relevant are of brain via thalamus (except for smell)
8
Q
Interpretation
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Sensory info is given meaning. Use of existing info such as info from memory to make sense of sensory input.
9
Q
Visual Sensation
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Is the detection or awareness of the presence of light energy produced by stimulation of visual receptors in the eye
10
Q
Visual Perception
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Is the selection, organisation and interpretation of visual sensations by the brain into meaningful objects and events
11
Q
Structures of the Eye
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Cornea Aqueous Humour Pupil Iris Lens Ciliary Muscles Virteous Humour Retina (Rods and Cones)
12
Q
Cornea
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Transparent, convex-shaped covering that protects the eye and helps focus light rays on the retina
13
Q
Aqueous Humour
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Watery fluid that helps to maintain the shape of the eyeball and provide nutrients and oxygen to the eye
14
Q
Pupil
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Black circle in the centre of the eye. The pupil is an opening in the iris that helps control the amount of light entering the eye
15
Q
Iris
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Coloured part of the eye that contains muscles that control the size of the pupil (dilation or contraction)
16
Q
Lens
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Transparent, flexible, convex structure located behind the pupil. Focuses light onto the retina by adjusting its shape according to the distance of the object being viewed
- Bulges to focus on nearby objects
- Flattens to focus on distant objects
17
Q
Ciliary Muscles
A
Attached on each end of the lens; control the shape of the lens
18
Q
Virteous Humour
A
Helps maintain shape of eyeball and focuses light
19
Q
Retina
A
Recieves and absorbs light; processes images
Consists of visual receptors cells called photoreceptors (rods and cones)
The image focused on the retina is upside down (inversed) and reversed (back to front). The brain rearranges this image to represent what is in reality
20
Q
Rods
A
- 120 million
- Respond to very low levels of light
- Responsible for night vision and peripheral vision
- Black and white vision
- Poor at detecting fine detail
- Sensitive to movement
21
Q
Cones
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- 6 million
- Respond to high levels of light
- Detect fine detail and are involved in colour vision
- Detect long, medium and short wavelengths = trichromatic vision
22
Q
Optic Nerve
A
Transmits visual info from the retina to the primary visual cortex of the brain
- exists eye at back of retina - no photoreceptors here = blind spot
23
Q
Optic Chiasm
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Point where axons cross from optic nerve into cortexs’
24
Q
Visual Perception Principles
A
Rules that we apply to visual info to assist our organisation and interpretation of the info in consistent and meaningful ways
25
Gestalt Principles
Refers to how we organise the features of a visual scene by grouping them to perceive a whole and complete form
"The whole is greater than the sum of its parts"
26
List the Gestalt Principles
Figure Ground Organisation
Closure
Similarity
Proximity
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Figure Ground Organisation
We organise visual info by perceptually dividing a visual scene into a figure which stands out from the background
Usually achieved by separating figure and ground by a line or boundary (contour)
- Reversibility
- Camouflage
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Reversibility
When the figure and ground are ambiguous, our perception is dependent on which aspect of the visual scene we label as the figure
29
Camouflage
Occurs when the figure and ground are not easily separated, but instead blend together
Occurs when the figure and ground are of similar colours and textures
30
Closure
The perceptual tendency to mentally 'close up', fill in or ignore gaps in a visual image. This is so we can perceive objects as a complete or whole.
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Similarity
The perceptual tendency to perceive parts of a visual image that have similar features
We often group features of an image according to size, shape, texture or colour, perceiving them as a whole
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Proximity
The perceptual tendency to perceive parts of a visual image which are positioned close together as a whole
33
Depth Perception
The ability to accurately estimate the distance of objects and therefore perceive the world in 3D (despite or retina only holding 2D images)
- Binocular and Monocular depth cues
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Binocular Depth Cues
Require the use of both eyes working together to provide information to the brain about depth and distance
Important when determining distance of nearby objects
35
List the Binocular Depth Cues
Convergence
| Retinal Disparity
36
Convergence
The brain detects and interprets depth and distance from changes in tension in the eye muscles when the two eyes turn in to focus on close objects
Greater Tension = close object
Less Tension = object further away
Useful for objects up to 6m away
37
Retinal Disparity
The different in location of the visual imagine on each retina is combined to judge the depth/ distance of an object
Each eye receives slightly different visual image from a diff angle; the info about difference is combined and interpreted by the brain to give us the depth and distance of an object
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Monocular Depth Cues
Require the use of only one eye to provide info on the depth and distance to the brain
39
List the Monocular Depth Cues
```
Accommodation
Linear Perspective
Interposition
Texture Gradient
Relative Size
Height in visual field
```
40
Accommodation
Lens of the eye bulges or flattens to accommodate close or distant objects on the retina
Brain monitors the ciliary muscles to judge depth and distance
Automatic focusing mechanism of the lens
41
List the Pictoral Depth Cues
```
Linear Perspective
Interposition
Texture Gradient
Relative Size
Height in Visual Field
```
42
Pictoral Depth CUes
Secondary external depth cues - depth and distance on 2D surfaces
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Linear Perspective
Apparent convergence of parallel lines as they recede into the distance
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Interposition
Overlapping objects, front object appears closer than object behind
45
Texture Gradient
Judgement on depth and distance influenced by amount of fine detail seen on surfaces
46
Relative Size
Tendency to visually perceive object with largest image on retina as closest and vice versa
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Height in Visual Field
Location of objects in visual field determines perceived distance
Closer to horizon = more distant
48
Perceptual Constancies
Refers to the tendency to perceive an object as remaining stable and unchanged (constant) despite any changes that may occur to the image that is casted onto the retina
49
List the Perceptual Constancies
Size Constancy
Shape Constancy
Brightness Constancy
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Size Constancy
The tendency to perceive an object as maintaining its size, despite any changes to the size of the image cast on the retina
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Shape Constancy
The tendency to perceive an object as maintaining its shape despite any change in shape of the image of the object on the retina
52
Brightness Constancy
The tendency to perceive an object as maintaining its level of brightness in relation to its surroundings, despite changes in the amount of light being reflected from the object to the retina
53
Perceptual Set
The predisposition or readiness to perceive something in accordance with what we expect it to be
54
List the Factors that influence Perceptual Set
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Context
Motivation
Emotional State
Past Experience
Culture
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Context
Refers to the setting or environment in which a perception is made. When interpreting visual info, we take into account the setting and pay more attention to those aspects that are immediately relevant
Focusing role = allows for quick interpretation of setting
56
Motivation
Visual perception can be influenced by our motivation when we see what we want to see, rather than what is actually there
Influenced by psychological and biological factors
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Emotional State
Different emotions can set us to perceive info in a particular way consistent with the emotion being experienced
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Past Experience
Refers to our personal experience throughout our lives (including everything we have learnt both intentionally and unintentionally)
Unique combination of experiences can set us to perceive info in a particular way
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Culture
Refers to the way of life of a particular community or group that sets it apart from others (customs, traditions, beliefs)
Experience within these particular cultures can influence the way that we process and interpret visual info
60
Taste (Gustation)
Starts with the physical stimulation of taste receptors in the mouth
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Process of taste sensation and perception
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Stimulus
Reception
Transduction
Transmission
Interpretation
```
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Stimulus of Taste Sensation
Chemical molecules combine with saliva on your tongue (=tastant)
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Reception of Taste Sensation
The molecules stimulate sensory taste receptors, which are located in the taste buds that are grouped within papillae
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Transduction in Taste Sensation
Taste receptors convert chemical molecules into electrochemical energy that can travel as action potentials
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Transmission in Taste Sensation
Electrochemical energy travels along facial cranial nerve via thalamus to the primary gustatory cortex
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Taste Receptors
Sensory receptors that detect the chemical molecules that enable taste
10 day lifespan
Centre of tongue = blind spot for taste (no taste receptors)
Specialised taste buds are spread evenly throughout tongue
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Taste Buds
Taste receptors are located within taste buds. Most on tongue but also found under tongue or in mouth
Number of taste buds decreases with age
68
Papillae
Small bumps on tongue surface that contain taste buds. May contain one or more taste buds.
69
Taste Pores
Open into taste bud. Connect the surface of the tongue to taste receptors that are in the taste buds. Achieved via gustatory hairs
70
List the Influences on Taste Perception
Age
Genetics
Perceptual Set
Culture
71
Age on Taste Perception
Taste buds become more numerous during physiological development
Evolutionary predisposition to avoid bitter tastes at a young age
Because less responsive to taste as we age
Taste perception evident at birth - sucking on sweet substances
72
Genetics on Taste Perception
We are more or less sensitive to taste depending on our genetic predisposition
Supertasters experience intense taste sensations 2-3 times more intense than the majority of people; thought to have inherited a very high no of taste receptors
73
Perceptual Set on Taste Perception
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We taste what we expect to taste
We expect food to look a certain way
Process of taste perception begins with the eyes
Past experiences shape our expectations
Can benefit survival
```
74
Culture on Taste Perception
We generally prefer tastes that we grow up with
These start in utero and directly after birth (breastfeeding)
We can change taste preferences as we develop, due to families, socio economic factors etc
75
A Perceptual Distortion
An inconsistency or mismatch between our perceptual experience and our physical reality
76
Visual Illusions
A consistent misinterpretation (distortion or mistake) of real sensory info
Mismatch between our visual perception and physical reality
77
Muller-Lyer Illusion
The line with the feather tail at each end is periceved as being longer than the line with the arrow head at each end
78
Biological Explanation 1 of Muller-Lyer Illusion
Eye Movement Theory proposes that the lines require different types/ amount of eye movement. The feather tailed line is longer so lengthens eye movement required to view line therefore perceived as longer
Rejected bc occurs when no eye movement occurs
79
Biological Explanation 2 of Muller-Lyer Illusion
Specific brain areas have been found to be active and inactive when viewing the illusion
Not satisfactory explanation
80
Psychological Explanation of Muller-Lyer Illusion
We experience the illusion due to the fact that it contradicts what we have learned throughout life about physical reality
81
Carpentered World Hypothesis
Learning based explanation that suggests the illusion occurs because of its similarity to familiar architectural features in the real 3D world
Our brain overrides the info from the retinal images showing two vertical lines as equal in length
Line that appears further away is perceived as longer
82
Social Perspective of Muller-Lyer Illusion
Environment is a key factor in perceiving the illusion
Some cultures, people live in a non carpentered world - past experience and learning - likely to view lines in their actual 2D forms therefore perceive lines as equal length
83
Ames Room Illusion
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Room's trapezium shape combined with the restriction of only being able to use monocular vision through the peephole provide the basis for the illusion
Size constancy manipulated, shape constancy consistent
Perceptual Set (Carpentered World)
```
84
Flavour
A perceptual experience produced by a combination of taste and other sensations
A multi-sensory process and is influenced by numerous factors including perceptual set, colour intensity and texture
85
Perceptual Set on Flavour
The flavour we experience is influenced by our expectations
This is based on preconceived ideas about how something should taste
Colour plays a crucial role in our expectation of how something will taste - we associate particular colours w certain flavours
If colour of food/ drink is different, our brain can interpret that it tastes differently too
86
Colour Intensity on Flavour
There tends to be an expectation that more intensely coloured foods are likely to be more intensely flavoured
A brighter coloured food item can seem to taste differently to a blander coloured one, even when there is no change in ingredients
87
Texture on Flavour
Texture is the property of food/ drink that is felt in the mouth and contributes to flavour along with taste, vision and other sensations
Affects flavour by:
- texture of food determines how much its surface area can stimulate taste receptors
- texture affects how long the food stays in the mouth and is exposed to taste receptors
88
Synaesthesia
A perceptual experience in which stimulation of one sense produced additional unusual experiences in another sense
89
Characteristics of Synaesthesia
- real not imagined
- involuntary
- automatic response to relevant sensory stimulation
- vivid, highly memorable and consistent
- synaesthesia is one way
90
Research Findings about Synesthesia
- unusual brain processes involved
- relatively rare (1/2000)
- some types more common than others eg grapheme colour synesthesia
- individual differences in experience/ severity of condition
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Possible Explanations of Synesthesia
- high sensitivity to external stimuli
- breakdown of sensory and perceptual processes
- excess of neural connections from early development
- unique structure/ function of brain - abnormal neural pathways that cross activate each other
