PSYC1003 Lecture Notes - Lecture 2: Symmetry, Akinetopsia, Ataxia
Sensation and Perception
Sensation
The process by which sense organs (eyes, ears, smell, taste, touch) gather
information about the environment and transmit this information to the brain for
initial processing
The registration of physical stimuli from the environment by the sensory organs
Sensory impressions are affected by context, experience, and emotional states
Perception
An active process (closely related to sensation) by which the brain selects, organises,
and interprets sensations
What we do with the information from sensation- e.g. turns shapes and colours into
recognising the world and creating a meaningful picture
Our perceptual experience is not an objective reproduction of what is out there,
instead it is a construction of reality that is manufactured by the brain
Three principles emerge from the study of sensation and perception:
There is no one-to-one correspondence between physical and psychological reality,
measuring this is called psychophysics (reaction time, accuracy)
Sensation and perception are active processes
Sensation and perception are adaptive (facilitate survival and reproduction)
Difference between perception and sensation
Sensory stimulation might be the minor task of the cortex, whereas its major task is
to predict upcoming stimulations as precisely as possible
Neural signals are related less to a stimulus than to its congruence with internal
goals and predictions, calculated on the basis of previous input to the system
Visual Perception
Organising Sensory Experience- Perceptual organisation (organises a continuous
array of sensory experience into meaningful units)
oForm perception
oDepth or Distance Perception
oMotion Perception
oPerceptual Constancy
Interpreting Sensory Experience
oInfluence of Experience
oBottom-up and Top-down Processing
oExpectations and Perceptions
oMotivation and Perception
Form Perception
Organises sensations into meaningful shapes and patterns
Gestalt psychologists introduced five basic principles:
oFigure-Ground Perception
E.g. birds vs sky
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oSimilarity
E.g. circles form the letter r
oProximity
E.g. three pairs of lines seen together in pairs
Things close together must have similar form
oGood Continuation
E.g. continuous lines and shapes rather than pie with extended lines
Impose continuation
oSimplicity
Simplest interpretation
oClosure
Incomplete figures are seen as complete
Impose some closure, try to make an object from what is presented
The brain automatically and unconsciously follows these as it organises sensory
inputs into meaningful wholes
Gestalt principles are based on the view that perception is not like taking a
photograph, instead perception is an active experience of imposing order on an
overwhelming panorama of details by seeing them as parts of larger wholes (or
gestalts)
Preserved figure-ground segregation and symmetry perception
Figure-ground is a low-level process that happens before the brain processes
information
Patients with stroke in right side of brain that can't process or perceive left side of
vision are still separating figure-ground
Happening on a lower level of the brain that is still functioning and sending signals
Can see the outline because it is on the right side of the object but don't properly
perceive it or understand the difference between object and background
Perceptual Constancy
We are imposing things on everything we see
Size: objects do not differ in size when viewed from different distances
Colour: we perceive object colour as stable, even under conditions of changing
illumination
Shape: we recognise an object as having the same shape, even when we view it from
a different angle at a different distance
Interpreting Sensory Experience
Expectations about perception are influenced through:
oContext
oSchemas
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Document Summary
The process by which sense organs (eyes, ears, smell, taste, touch) gather information about the environment and transmit this information to the brain for initial processing. The registration of physical stimuli from the environment by the sensory organs. Sensory impressions are affected by context, experience, and emotional states. An active process (closely related to sensation) by which the brain selects, organises, and interprets sensations. What we do with the information from sensation- e. g. turns shapes and colours into recognising the world and creating a meaningful picture. Our perceptual experience is not an objective reproduction of what is out there, instead it is a construction of reality that is manufactured by the brain. Three principles emerge from the study of sensation and perception: There is no one-to-one correspondence between physical and psychological reality, measuring this is called psychophysics (reaction time, accuracy) Sensation and perception are adaptive (facilitate survival and reproduction)
