Sensation and perception

Question 1

Sensation

Answer 1

• The process by which our sensory receptors and nervous system receive and represent stimulus energies from our environment
• The brain receives input from the sensory organs

Question 2

Perception

Answer 2

• The process of organizing and interpreting sensory information, enabling us to recognize meaningful objects and events
• The brain ‘makes sense’ out of the input from sensory organs

Question 3

Bottom-up processing

Answer 3

• Taking sensory information and then assembling and integrating it
• What am I seeing?
  1. Reception: the stimulation of sensory receptor cells by energy
  2. Transduction: transforming this cell stimulation into neural impulses
  3. Transmission: delivering this neural information to the brain to be processed

Question 4

Top-down processing

Answer 4

• Using models, ideas, and expectations to interpret sensory information
• Is that something that I’ve seen before?

Question 5

Signal detection

Answer 5

: whether or not we detect a stimulus
- Our detection is influenced by:
 physical intensity of the stimulus
 psychological factors: experience, expectations, motivations, and alertness

Question 6

Subliminal detection

Answer 6

• Below our threshold for being able to consciously detect stimulus
• We cannot consciously learn from subliminal stimuli
• We can be primed by these stimuli (the effect of subliminal stimuli appears in our subsequent choices and behaviour)

Question 7

Perceptual set

Answer 7

• What we expect to perceive influences what we do perceive (example of top-down processing)

Question 8

Vision: energy, sensation, and perception

Answer 8

• Light is waves of electromagnetic radiation
• Our eyes respond to some of these waves
• Our brains turn our eyes’ responses to these waves into visual information

Question 9

Colour and brightness

Answer 9

• The colour or hue of light is related to its wavelength or frequency
• The brightness or intensity of light is related to the height or amplitude of light waves

Question 10

How we perceive visual information:

Answer 10

• Light enters through the cornea
• Light makes it way through the pupil
• The pupil is controlled by the iris
• Light is refracted through the lens and focuses the light on
• The retina which contains photoreceptors
• Most photoreceptors are found in small section of the retina called the fovea
• The photoreceptors turn the light energy to neural signals
• The optic nerve carries the signals to the rest of the brain

Question 11

Photoreceptors

Answer 11

• Light activates photoreceptor cells in the retina
• Rods: permit black-and-white, low-detail vision
• Dense in periphery of retina, much more common than cones
• Cones: permit high detail colour vison
• Dense in center of retina (‘fovea’)

Question 12

Information processing

Answer 12

• The images we ‘see’ are not made of light, they are made of neural signals by stimulating photoreceptors
• Signals are carried through the optic nerve to the thalamus and then to the visual cortex (occipital lobe)
• Neurons in primary visual cortex responds to certain basic features (orientations of lines, edges, direction of movement)
• In association areas of cortex, neurons respond to more complex combinations of features ( permit perception of more complex forms, such as faces
  Light waves  chemical reactions  neural impulses  objects

Question 13

Parallel processing

Answer 13

Allows for different components of perception to be processed at the same time (instead of serially)

Question 14

Prosopagnosia

Answer 14

• inability to recognize faces
• associated with damage to fusiform gyrus of temporal lobe

Question 15

Colour vision

Answer 15

• We perceive colour based on the wavelengths of light reflected by objects
• Young-Helmholtz Trichromatic (Three-colour theory)
   three types of colour receptors (cones): red, green, and blue
   each cone type is sensitive to particular wavelengths of light
   everything we perceive are created by light waves stimulating combinations of these cones

Question 16

Opponent-process theory

Answer 16

 neural process of perceiving white as the opposite of perceiving black
 yellow VS blue
 red VS green

Question 17

Perceptual organization

Answer 17

1. How do we perceive complex shapes and forms from individual details?
2. Distinguishing figures from background
3. Grouping parts into wholes (‘Gestalt’)
4. Perceiving form, motion, and depth
5. Maintaining shape and colour constancy despite changes in visual information
6. Using past experience to guide visual interpretation