Sensation

1
Sensation Perception

• Unit 3
• Chapter 4

2
Sensation

• Stimulation of sensory receptors and transmission
  of sensory info to the central nervous system
  (spinal cord/brain)
• Sensory receptors
• Stimulation automatic
• Presence of chemicals

3
Absolute Threshold

• Weakest amount of stimulus that can be sensed
• Vision, hearing, smell, taste, touch
• Differ from person to person
• Psychological factors
• Biological factors

4
Examples of Absolute Thresholds
Sense Absolute Threshold
Vision A candle flame seen at 30 miles on a dark clear night
Hearing The tick of a watch under quiet conditions at 20 feet
Taste One teaspoon of sugar in two gallons of water
Smell One drop of perfume diffused into entire volume of a six room apartment
Touch The wing of a fly falling on your cheek from a distance of 1 centimeter
5
Difference Threshold

• Minimum amount of difference detected between 2
  stimuli

6
Signal-Detection Theory

• Method for distinguishing sensory stimuli that
  accounts for stimuli strengths, and setting, your
  physical state, your mood, your attitude
• Also considers psychological factors
• Motivation
• Expectations
• Learning

7
Perception

• Psychological process through which we interpret
  sensory stimulation
• Reflects learning, expectations, attitudes
• Way in which we organize our sensory information

8
Closure

• Tendency to perceive a complete or whole figure
  even when there are gaps in what your senses tell
  you
• Fill in the blanks

9
Ground-Figure Perception

• Figures against a background
• What we perceive as figure and what we perceive
  as background influence our perception

10
(No Transcript)
11
Proximity

• Group together events that are near each other
• Things which are close together are seen as
  belonging together

12
Continuity

• Perceive things as belonging together if they
  form some type of continuous pattern

13
Similarity

• Occurs when objects look similar to one another
• See groups which have the same characteristics

14
Common Fate

• Tendency to perceive objects that are moving
  together as belonging together

15
Depth Perception

• Monocular Cues
• Need only one eye to be perceived
• Cause certain objects to appear more distant from
  the viewer than others
• pictorial depth cues-
• clues about distance given in a flat picture

• Binocular Cues
• Visual cues for depth that require the use for
  both eyes
• retinal disparity- images projected to different
  locations on right and left retinas
• convergence- sensing the eyes converging toward
  each other as they focus on closer objects

16
Stroboscopic Motion

• illusion of movement
• rapid progression of images or objects not moving
  at all
• our perceptions
• fill in the gaps

17
Stroboscopic Photography
18
Vision

• Unit 2.2

19
The Human Eye

• cornea- transparent tissue where light enters the
  eye
• pupil- opening in center of iris that allows
  light to pass into the eye
• iris- controls pupil size

• lens- focuses the light rays on the retina
• retina- contains sensory receptors that process
  visual information and send it to the brain
• optic nerve- carries visual info to brain

20
Near Far

• Nearsightedness
• Close objects are seen clearly but distant
  objects appear blurry
• Eyeball is too long
• Farsightedness
• Distant objects seen clearly but close objects
  appear blurry
• Eyeball is too short

21
Rods and Cones

• 2 kinds of photoreceptors
• Neurons that are sensitive to light
• Rods are sensitive to only brightness
• Allow us to see black/white
• Cones provide color vision

22
Dark and Light Adaptation

• Dark- adjustment to lower lighting
• Continues to improve for up to 45 minutes
• Light- adjustment to bright lighting
• Occurs within minutes

23
Visual Acuity

• Sharpness of vision
• Determined by ability to see visual details

24
Color Vision

• Cones enable us to perceive color
• Sensitive to blue, green, red
• Multi cone stimulation allows for other colors to
  be seen
• Other colors are created through combinations of
  red, blue, green

25
Color Compliment

• Afterimage of a color is its complimentary color

26
Color Blindness

• People who dont have normal color vision
• Partially or totally unable to distinguish color
• Malfunction of cones
• Total color blindness is rare
• Sensitive to only light and dark
• Partial color blindness is more common
• See red green but have hard time distinguishing
  between the two

27
Depth Perception

• Monocular Cues
• Need only one eye to be perceived
• Cause certain objects to appear more distant from
  the viewer than others
• Perspective, clearness, shadow

• Binocular Cues
• Visual cues for depth that require the use for
  both eyes
• retinal disparity- depth of an object
• convergence- both eyes focus on the same object

28
Hearing

• Unit 2.4

https//www.youtube.com/watch?vflIAxGsV1q0
29
The Ear

• Outer ear- collects and sends sounds to the
  eardrum
• Cochlea- transforms sound vibrations to auditory
  signals
• Auditory nerve- transmits neural impulses to brain

30
Deafness

• Conductive
• damage to middle ear
• Affects sound amplification
• Can be corrected with hearing aids

• Sensorineural
• Damage to inner ear, auditory nerve
• Absence of sound perception for certain
  frequencies
• artificial ear

31
Other Senses

• Unit 2.5

https//www.youtube.com/watch?vEJud8MKrvBE
32
Smell

• Essential to taste
• Odors are detected by receptor neurons in
  nostrils
• React when molecules come into contact with them
• Send information about odor to brain via
  olfactory nerve
• Adapts quickly

33
Taste

• Sweet, sour, salty, bitter
• Flavor of food is more complex than taste
• Odor, texture, temperature, taste
• Receptors on taste buds of tongue
• Sensitivity to different tastes can be inherited
• Bitter taste blind
• Taste cells reproduce rapidly

https//www.youtube.com/watch?vkyrIxAXZISc
34
Skin Senses (Touch)

• Combination of pressure, temperature, pain
• Distinct sensory receptors
• Receive more than one type of sensory input

35
Pressure

• Sensory receptors (pacinian corpuscle) located
  around the roots of hair cells
• Fire where skin is touched
• Different parts of body more sensitive
• more fingertips, lips, nose, cheeks
• less shoulders, thighs, calves
• Rapidly adapts

36
Pain

• Receptors located all over body
• Not all equally sensitive to pain
• prostaglandins- help body transmit pain messages
  to brain
• Can experience pain in limbs no longer there
  phantom limb

https//www.youtube.com/watch?v1mHIv5ToMTM
37
The Gate Theory of Pain
38
Body Senses

• Vestibular- position of the body
• sensory organs located in the ears
• Enables balance
• Kinesthesis- position and movement of individual
  body parts
• Sensory organs in joints, tendons, muscles