Lecture 5&6: Sensation And Perception Flashcards
What is perception?
An active process where the brain selects, organises and interprets sensory inputs/information
What is sensation?
The stimulation of sense organs: eyes, nose, ears, tounge, skin
Process by which body gathers info about the environment and transmits the info to the brain for initial processing
What are a baby’s hearing capacities at birth?
Babies can hear BEFORE birth
Prefer complex sounds
Able to discriminate sounds
What are human hearing capacities at 2-3 months?
Babies can distinguish phonemas (e.g. Between ba and pa)
Likes mothers voice
What are human hearing capacities later in life?
Hearing loss occurs with age (presbycusis)
Decrements are greatest at high frequencies
Can’t detect soft sounds at particular frequencies
Responsiveness to startling noises lessens
What are the effects of hearing loss?
Impacts self care (although visual impairment has a larger impact)
Affects safety and enjoyment of life - decline in spec perception is the greatest impact on life satisfaction
What are vision capabilities of a new born?
Pattern and face perception
sensitivity to contrast
Preference to contour contrast and movement
Preference of complex over simple patterns
What are our visual capabilities as we age?
Becomes harder to focus on nearby objects, see in dim light, perceive colour
Cornea is more translucent and scatters light (doesn’t focus on the retina, blurry image)
Lean continues to yellow
What occurs to our vision from middle to older age?
Cataracts increase as a result of:
Reduction in light reaching retina
Acquity worsens, there is a sharp drop after 70
Macular degeneration - loss of vision in central visual field (retina)
What are the impacts of visual difficulties?
Older people’s self confidence
Extensive vision loss may affect leisure pursuits and be isolating (can’t drive)
What are the face perception capabilities of babies at 1,2 and 3 months of age?
Face perception is not innate, it is learned.
At 1 month- baby scans separate parts of face
2 months- integrate characteristics
3 months- can discriminate between photos of different strangers and recognise mother
What does perception of human face support?
An infants earliest social relationship
What are our taste and smell capabilities after 60?
Reduced sensitivity to tastes
Decreased smell receptors, leading to declines in sensitivity to odours (floral, musky, fruit or sweet)
What are our touch capabilities as we age?
Touch is crucial for blind people
There is a sharp decline of sensitivity in hands
All adults are affected after 70
What is the role of attention in perception?
Actively search environment to make sense of it
Can only process a finite amount of info
What we attend to determines what we perceive
What is perception influenced by?
Motives e.g. When hungry, hunger is the motive, we are more likely to notice the smell of food.
Expectations:
1) context e.g. In a bakery, more food, or at work, less food
2) schemas I.e. an enduring knowledge of structures
What are some specific medical applications of perception?
Symptom perception
What is symptom perception.
Internal and external stimuli compete for our attention
If the environment is boring we are more likely to pay more attention to our body and notice mor symptoms
Distraction can reduce symptoms (e.g. Thinking of something else to distract from pain)
What is a schema?
A cognitive framework that helps organize and interpret information in the world around us.
What is a schema in symptom perception?
Can drive searches for symptoms and influence interpretation e.g. Medical student disease (mass psychogenic illness)
What is the gate control theory of pain?
A theory about pain modulation that proposes that certain cells n the spinal cord acts as gates to interrupt and block some pain signals while sending other ones to the brain
What happens when the gate is closed? (Gate control theory)
Pain perception is inhibited by activity in a-β fibres, relaxation, distraction, positive emotion
What happens when the gate is open? (Gate control theory)
Pain perception is facilitated by anxiety, depression, attention
What causes pain stimulus in the gate control theory?
Activity in A-δ and C fibres
What is perceptual organisation?
The organisation of a continuous array of sensations into meaningful units.
What are the four aspects of perceptual organisation?
Form perception
Depth or distance perception
Motion perception
Perceptual constancy
What is form perception?
Perception which organises sensory info into meaningful shapes and patterns e.g. Gestalt view, where the whole is more than the sum of the parts
What are the 5 gestalt principles?
The law of proximity- people to to group together the nearest elements
The law of similarity- people tend to group together the most similar elements
The law of good continuation- people experience lines as continuous even when they are interrupted
The law of closure- people tend to fill in small gaps to experience objects as wholes
The law of common fate- people tend to group together objects that appear to be moving in the same direction
What is depth or distance perception?
The organisation of perception in three dimensons
What are the two kinds of visual info that provides important information about depth and distance?
Binocular cues: visual input integrated from the 2 eyes
Monocular cues: visual input from 1 eye
What are some monocular depth perception cues?
Interposition Linear perspective Texture gradient Shading Aerial perspective Familiar size, Relative size
What is interposition?
When an object blocks out part of another object
Gives depth info indicating that the blocked out object is further away
What is linear perspective?
A depth cue that depends on the size/distance relation.
E.g. When parallel lines recede into the distance, they converge towards a point on the horizon in your retinal image
Your visual interpretation will give the Ponzo illusion where the image looks long and like its going into the distance as the parallel lines converge
What is texture gradient?
Depth cues due to the density of a texture becomes greater as a surface recedes in depth,
The units that make up the texture become smaller as they recede into the distance. Your visual system interprets this diminishing texture as greater distance in 3dimensional space
What is shading?
Concluding surfaces block out lights creating shadows that can be used as an additional source of depth info.
What is aerial perspective?
the effect the atmosphere has on the appearance of an object as it is viewed from a distance. As the distance between an object and a viewer increases, the contrast between the object and its background decreases, and the contrast of any markings or details within the object also decreases.
What is familiar size?
A perceptual cue in which the known (familiar) size of an object is used to judge its distance from the observer.
What is relative size?
Involves the basic rule of light projection in which objects of the same size at different distances project images of different sizes on th retina,
The closest object projects the largest image and the furtherest object, the smallest image.
This is called the size/distance relation
What are the 2 sources of binocular depth perception?
Retinal disparity: each eye gets a different picture of the world. The greater the difference between the pictures, the closer the object
Convergence: eyes point inwards when looking toward close objects and move out wards when looking at distant objects
