The study of psychophysics

1

• The study of psychophysics

2
Sensation

• A message our brain receives from our senses.
• Genetic factors are more influential on sensation
  whereas cultural factors are more influential on
  perception.

3
What do you see?

• Influenced by genetics

4
cont. What do you see?

• Influenced by environment/culture

5
Psychophysics

• Is the study and measurement of the functioning
  of the senses.
• In studying psychophysics there are some key
  terms
• Detection active, usually conscious sensing of a
  stimulus
• Absolute threshold minimum detectable amount of
  physical energy for a sensation influenced by
  fatigue, distractions, a cold.

6
Signal-detection theory

• 4 possible stimulus/response outcomes
• Hit(stimulus/detection)
• Miss(stimulus/undetected)
• False alarm(no stimulus/detection)
• Correct rejection(no stimulus/undetected)

7
continue key terms

• Discrimination distinguish one stimulus from
  another
• Just noticeable difference minimum amount of
  difference that can be dtected between 2 stimuli
  (Weber)

8
Biological properties common to all senses

• Receptor cells
• Tranduces (converts) incoming energy to
  electrochemical form of energy
• Sensory coding (intensityamount of
  energy)/qualitynature of stimulus
• Sensory adaptation

9
Visiondetect wavelengths from about 350-750
nanometers

• Anatomy
• Cornea clear dome-shaped window
• Pupil hole in the center of the eye
• Iris circular muscle/ eye color
• Retina network of neurons transforming
  electromagnetic light

10
cont. vision

• energy into neural electrochemical impulses.
• Ganglion cells first layer of neuronal tissue
  whose axons constitute the optic nerve
• Amacrine cells/ horizontal cells/ bipolar cells
  second layer of interneuron

11
cont. vision

• Photorecptors 2 kinds
• Rods black/white
• Cones colors
• Blind spot

12
Hearing

• Sound travels 750 mph in air 3000 mph in water
• Sound has 3 physical properties
• Amplitude loudness
• Pitch high/low
• Frequency fast/slow
• Frequency/wavelength are inversely related ie.,
  short wavelength higher/faster frequency.

13
Anatomy of the ear

• Outer
• Middle
• Inner
• How do we hear
• Place theory
• Frequency theory
• Duplicity theory

14
Taste

• 4 primary tastes
• Saltiness
• Bitterness
• Sweetness
• sourness

15
Smell

• Anatomy of smell
• Olfactory epithelium
• Pheromones chemical substances secreted by
  animals which trigger specific reactions in
  another animal
• Humans react psychologically to smell

16
Skin and body senses

• Skin senses
• Pressure
• Temperature
• pain

• Body senses
• Kinesthesis awareness of skeletal movement/
  positioning
• Vestibular balance

17
Perception

• The process by which we recognize, organize, and
  make sense of sensations.
• 2 types of perception
• Space perception
• Form perception

18
Space perception 2 types

• Monocular depth cues
• Relative size
• Texture gradient
• Interposition
• Linear perspective
• Location in the picture plans
• Aerial perspective
• Binocular depth cues

19
Form perception 2 types

• Feature-detector approach
• Various neurons in visual cortex can be mapped to
  specific receptive fields on the retina
• Differing cortical neurons respond to different
  kinds of forms, such as lines.

20
cont. feature-detector

• Visual perception seems to depend on increasing
  complexity in cortical neurons.

21
Gestalt approach

• Figure ground
• Proximity
• Similarity
• Closure
• Continuity
• symmetry

22
Cont. Gestalt Approach
23
Perceptual constancy

• Perception of an object remains the same even
  when our immediate sensation of the object
  changes.

24
Problems with perception

• Agnosia deficit in ability to perceive sensory
  information
• There is normal sensation.