Perception and Sensation Flashcards
What is sensation?
The detection of simple properties of stimuli such as brightness, colour, warmth and sweetness
What is perception?
The detection of objects, their locations, their movements and their backgrounds
What is functional validation?
The notion that the nervous system has to be stimulated during development in order for it to develop properly
Transduction is…
The process by which the sense organs convert energy from environmental events into neural activity
What is anatomical coding?
Coding dependent on the anatomical location of the nerve, for example, you can distinguish between a touch on the arm or the knee as different nerves are stimulated
What is temporal coding?
Coding information in terms of time, the simplest form is rate, firing at a faster or slower rate according to the intensity of the stimulus
Just-Noticeable difference
- Ernst Weber
- The smallest change in magnitude of a stimulus that a person can detect
What is the JND for weight?
1 in 40
What is the JND for brightness of white light?
1 in 60
What are the ratios of JNDs called?
Weber ratios
What is the difference threshold?
The minimum detectable difference between two stimuli
What is an absolute threshold?
The minimum value of the stimulus that can be detected from no stimulus at all
According to signal detection theory, every stimulus event requires discrimination between ____ and _____
Signal (stimulus); noise (both background and nervous activity)
The systematic study of the relation between the physical characteristics of stimuli and the sensations they produce is called
Psychophysics
An important principle of signal detection theory is that detection of any stimulus requires that we discriminate between __________ and __________
Signal; noise
The human retina contains two types of photoreceptors; they are
Rods and cones
The chemosenses are our senses of
Taste and smell
Unlike information from other sensory modalities, olfactory information is sent directly to the
Limbic system
The Gestalt principle which states that elements that are positioned closely together as a group will be perceived as belonging together is the __________ principle
Proximity
Bottom-up processing is to __________ as top-down processing is to __________
Data driven; context driven
A series of studies by Perrett et al. has demonstrated that perceived facial attractiveness is related to having a(n)
Thinner jaw
Stereopsis occurs because
Each eye receives a slightly different image of a visual scene
The top of a convex object appears light coloured while the bottom appears darker. Thus, our visual system appears to interpret this object as if it were illuminated from above. The cue to depth at work in this context is
Shading
The Sapir-Whorf hypothesis states that
Language can determine thought
If you wanted to make a white card look whiter you would place it
On a grey background
Tootell et al. (1995) asked people to watch series of concentric rings moving outwards. When the rings suddenly stopped moving, participants reported seeing
Continued movement in an inward direction
It is possible to create the illusion of movement by alternately turning on and off two small lights in a darkened room. This apparent movement of the light between two positions is called the
Phi phenomenon
What is a dichromat?
An individual who is missing a photopigment and therefore use only two primary colours
What is an anomalous trichromat?
An individual who has an altered photopigment
What is protanopia?
- A lack of the photopigment in red cones (red cones filled with green photopigment)
- Red looks much darker than green, reds and oranges look very dark as the red end of the spectrum cannot be seen
What is deuteranopia?
Green cones are filled with red photopigment
What is tritanopia?
- Loss of blue cones (not determined whether they are missing or filled with another pigment)
- See the world in green and red, a blue sky looks bright green and yellow looks pink
What is synaesthesia?
Individuals who can sense colours when hearing words or those who can sense shapes from tastes
The human ear perceives vibrations between approximately ____ and _____
30 Hz; 20000 Hz
What qualities of sound are used to locate it?
- Relative loudness
- Difference in arrival time
What are the principles of Gestalt psychology
- The adjacency/proximity principle
- The similarity principle
- The good continuation principle
- The principle of common fate
What is the adjacency/proximity principle?
Elements that are closest together will be perceived as belonging together
What is the similarity principle?
Elements that are similar in looks will be perceived as belonging together
What is the good continuation principle?
It is simpler to perceive a line which takes a smooth course rather than making a sharp bend
What is the principle of common fate?
Elements that move in the same direction will be perceived as belonging together and forming a figure
What is the law of closure?
Our visual system often supplies missing information and ‘closes’ the outline of an incomplete figure
What is bottom-up processing?
- Also called data-driven processing
- Perception is constructed out of the elements
What is top-down processing?
- Use of contextual information to aid perception
Binocular cues of depth
- Convergence
- Retinal disparity
Monocular cues of depth
- Pictorial cues
- Motion parallax
When the eyes converge on a distant object, the angle between them is ______ than when they converge on a close object.
Smaller
The perception of depth using retinal disparity is called _______
Stereopsis
What is backwards masking?
If two visual stimuli are presented, one after the other, the second stimulus can sometimes erase the image of the first
Why is backwards masking important?
It allows us to read without the image of what we have previously read masking the next sentence
What is achromatopsia?
- Damage to the lingual and fusiform gyri in the visual cortex
- A form of colour blindness which causes the world to be seen in shades of grey
What is the geniculostriate pathway responsible for?
Identifying stimuli and discriminating between patterns
What is the retinotectal pathway responsible for?
Locating objects in space
Which part of the brain appreciates an objects qualities?
The inferior temporal cortex
What part of the brain has the ability to locate an object?
The posterior parietal cortex
Where did DF experience?
Bilateral damage to the occipital cortex
What could DF not do?
Discriminate between geometric shapes and recognise or identify objects (no language or sensory impairment)
What is blindsight?
Then phenomenon that some people can lose substantial areas of the PVC, meaning they are ‘cortically blind’, but still show evidence of perceiving objects
Name a famous case of blindsight
DB
What is visual agnosia?
Difficulty in recognising objects
Name a famous case of visual agnosia
Patient DF
What is the difference between apperceptive agnosia and associative agnosia?
Apperceptive = the inability to recognise objects whereas associative = the inability to make meaningful associations to visually presented objects
What is prosopagnosia?
An impairment in the ability to recognise familiar faces
What is spatial neglect?
Difficulty in perceiving objects on one side of the body (left caused by right perietotemporal cortex damage and right caused by left damage)
Yellow light stimulates which cones in the eye?
Red and green
People have ______ senses
More than 5
An area of complete blindness in the visual field is called a(n)?
Scotoma
______ is the binocular cue that we use to judge the distance of objects close to our faces
Convergence
Weiskrantz’s famous patient DB suffered from _____ following surgery to remove a brain tumour in the area of ______
Blindsight; visual cortex
Signal detection theory and the _____ are two methods used by scientists to measure people’s sensations
Just noticeable difference
Because the brain has no direct information about the physical energy impinging on a given sense organ, it uses ______ to interpret the type of sensory stimulus according to which incoming nerve fibres are active
Anatomical coding
Traditionally, the tip of the tongue was thought to be particularly sensitive to ______ substances, the back of the tongue to _____ substances, and the sides of the tongue to _____
Sweet and salty; bitter; sour
