Sensation and perception

Question 1

Sensation

Answer 1

The active process of sensory organs detecting stimuli and information about the environment and translating them into nerve impulses to transmit to the brain for processing (transduction).

Question 2

Perception

Answer 2

The active process of the brain selecting, organising and interpreting sensation.

Question 3

Three principles for all senses

Answer 3

No one-to-one correspondence between physical and psychological reality, sensation and perception are active not passive and they are adaptive.

Question 4

Steps of sensation to perception

Answer 4

Stimulus received by sensory receptors.

Receptors translate stimulus properties into nerve impulses (transduction).

Feature detectors analyse stimulus features.

Stimulus features are reconstructed into neural representation.

Representation is compared with previously stored info in brain.

Matching process results in recognition and interpretation of stimulus.

Question 5

Absolute threshold

Answer 5

Minimum level of a stimulus needed to notice it at a hit rate of 50% in experimental conditions.

Question 6

Psychophysics

Answer 6

Studies relationships between physical attributes of stimuli and the psychological experience of them.

Question 7

Difference threshold

Answer 7

The lowest level of stimulation required to sense a change in stimulation has occurred - just noticeable difference JND.

Question 8

Signal detection theory

Answer 8

Judgment on whether a stimulus is present or absent, is reflected on the observer’s sensitivity to the stimulus and response bias (expectation and motivation).

Question 9

Sensory adaption

Answer 9

Tendency of sensory system to respond less to stimuli that continue without change.

Question 10

Subliminal perception

Answer 10

Tendency to perceive info outside of conscious awareness.

Question 11

Weber’s law

Answer 11

Regardless of the magnitude of two stimuli, the second must differ by a constant proportion from the first to be perceived as different. Expressed as a Weber fraction e.g. weight 1/50 and sound around middle C 1/10.

Question 12

Fechner’s law

Answer 12

Physical magnitude of stimulus grows logarithmically (1,2,4,8), as subjective experience of intensity grows arithmetically (1,2,3,4). People only experience a small percentage of actual increase in stimulus intensity.

Question 13

Steven’s power law

Answer 13

Perceived intensity grows in a linear fashion and actual magnitude of the stimulus grows exponentially. Perceived pain works the opposite as the greater the pain, the less additional intensity is required for a JND.

Question 14

Vision

Answer 14

Stimulus is electromagnetic energy (light) that travels in wavelengths of 400 (violet) -700 (red) nanometres, higher wavelengths is less energy. Light travels nearly 300,000 km per second. Light travels in straight lines and is absorbed or reflected.

Question 15

Transmission of visual information

Answer 15

Rods and cones> bipolar cells> ganglion cells> optic nerve. Light is focused on retina by cornea, pupil then lens through aqueous humour and vitreous humour.

Question 16

Cornea

Answer 16

Tough transparent tissue covering front of eye.

Question 17

Aqueous humour

Answer 17

Chamber of clear fluid that supplies cornea and lens with oxygen and nutrients.

Question 18

Pupil

Answer 18

Opening in centre of iris that dilates and constricts with muscle fibres.

Question 19

Lens

Answer 19

Elastic disc-shaped structure that focuses eyes (flattens for distance and becomes round for closer objects - accommodation).

Question 20

Vitreous Humour

Answer 20

Clear gelatinous liquid filling eye ball.

Question 21

Retina

Answer 21

Light sensitive (photosensitive) tissue at back of eye that translates light.

Question 22

Rods

Answer 22

Light recpetor/photoreceptor. 120 million in retina that are more sensitive to light allowing vision in dim light. Only produce sensation of black, grey and white. Concentrated off centre of retina. Does not transmit fine detail but excites bipolar cells more easily.

Question 23

Cones

Answer 23

8 million cones are in the retina. They are concentrated in the centre of the retina, this area is called the fovea. Clarity is achieved in bright light looking directly at the object. Cones respond to colour and black and white. They require more light to excite bipolar cells.

Question 24

Bipolar cells

Answer 24

Rods and cones excite bipolar cells by changing chemical structure in response to light (bleaching) by graded potentials.

Question 25

Ganglion cells

Answer 25

They have receptive fields that are excited or inhibited by bipolar cells’ sensory information. Axons make up the optic nerve and transmit visual information to the brain for processing.

Question 26

From eye to brain

Answer 26

Impulses from the optic nerve pass through the optic chiasm where the nerve splits. Information from the left half of each retina (right visual field) goes to left hemisphere and vice versa. Information then goes to the brain via the optic tracts. One pathway to vision is to the superior colliculus in mid brain, involved in controlling eye movements. The other pathway is to the lateral geniculate nucleus of the thalamus, then to the primary visual cortex in the occipital lobes. 25% of the visual cortex is devoted to the central 2% of visual field.

Question 27

Feature detectors

Answer 27

Specialised cells in cortex that only respond when stimulation in their receptive fields matches a particular pattern or orientation.

Question 28

What pathway

Answer 28

From primary visual cortex in occipital lobes through lower part of temporal lobes (inferior temporal cortex) determines what object is.

Question 29

Where pathway

Answer 29

Locates object in space, following its movement and guides movement towards it. It runs from priamary visual cortex to middle and upper temporal and parietal lobes.

Question 30

Young-Helmholtz or trichromatic theory

Answer 30

The eye contains three types of sensory receptors, sensitive to red, green or blue. Short-wavelength (S cones) sensitive to 420nm (blue) Middle (M cones) 535nm (green) and long wavelength (L cones) sensitive to 560nm (red). Operates at retina.

Question 31

Opponent process theory

Answer 31

Primary colours are linked in pairs: Blue-yellow, red-green, and black-white. Operates at neural levels.

Question 32

Psychological dimensions

Answer 32

Hue= colour, saturation= colours purity, lightness= light or dark.

Question 33

Audition

Answer 33

Hearing, the stimulus is vibrations of objects through the air. Sound waves travel 340 metres per second and gets weaker over distance. Sound can travel through objects.

Question 34

Frequency

Answer 34

Number of cycles per second expressed in Hertz (Hz). Adult hearing range is 15 to 20,000 Hz. Higher frequency = higher pitch. Doubled frequency is perceived an octave higher.

Question 35

Complexity

Answer 35

Most sounds are a combination of frequencies. Complexity corresponds to psychological property of timber or texture of sound.

Question 36

Amplitude

Answer 36

Is height and depth of a wave expressed in decibels (dB). Corresponds to psychological property of loudness.

Question 37

Transduction of sounds

Answer 37

Sound waves directed to middle ear with outer pinna (skin covered cartlidge) into auditory canal (amplifies sound by 2). Eardrum or tympanic membrane vibrates ossicles (amplifies sound by 2 or 3) transmitting vibration to oval window in inner ear. Vibration then causes pressure waves in cochlea fluid of vestibular canal which transmit to tympanic canal and both cochlea chambers flexing basiliar membrane and tectorial membrane. Transduction occurs in organ of corti and both membranes with hair like cells between them moving and triggering action potentials in sensory neuron forming the auditory nerve. Mechanical energy from cilia (hairs) and membranes seperating cochlea canals transduced into neural energy.

Question 38

Ossicles

Answer 38

Malleus, incus, and stapes, the small bones connected to eardrum. Stapes strikes oval window.

Question 39

Eustachian tube

Answer 39

Connects middle ear to throat to equalise ear pressure.

Question 40

Semicircular canals

Answer 40

Involved in balance.

Question 41

Cochlea

Answer 41

Hearing organ, technically a hollow bone that spirals 2.75 turns. Contains hearing organs.

Question 42

Place theory

Answer 42

Different areas of the basiliar membrane respond to different frequencies, accurate for higher frequencies.

Question 43

Frequency theory

Answer 43

Basilar membrane’s rate of vibration reflects the frequency with a sound wave cycles, explains sensation of low frequency sounds.

Question 44

Ear to brain

Answer 44

Information passes through cochlear nucleaus in medulla to olivary nucleus to inferior colliculus in mid brain to medial geniculate nucleus of thalamus to auditory cortex in temporal lobes.

Question 45

Sound localisation

Answer 45

Binaural neurons that respond to relative differences in loudness and timing of sensory signals transduced by ears.

Question 46

Olfaction

Answer 46

Smell, stimuli are invisible molecules of gas in the air. Air flows through olfactory epithelium where they are detected by 10 million olfactory receptors. The axons of these nerves form olfactory nerves transmit information to olfactory bulbs then to primary olfactory cortex in frontal lobes. Smell is not relayed through thalamus but olfactory cortex projects to thalamus and limbic system connecting smell to taste and emotion.

Question 47

Gustation

Answer 47

Taste, stimuli is molecules soluble in saliva. Most of flavour experience is contributed to smell. Taste occurs at tastebuds on tongue and throughout mouth (10,000). There are 50-150 taste receptor cells on each taste bud (replaced every 10 days). Neurons travel to medulla and pons then to thalamus and primary gustory cortex for identification or to limbic system for immediate emotional and behavioral responses.

Question 48

Touch

Answer 48

Touch includes three senses: pressure temperature and pain. The human body contains 5 million touch receptors. Sensory neurons synapse with spinal interneurons that stimulate motor neurons (produce reflexes) as well as neurons that carry information up the spinal cord to the medulla where nerve tracts cross over and information travels through thalamus to the somatosensory cortex.

Question 49

Gate control theory

Answer 49

Experience of pain is heavily influenced by CNS through the action of neural fibres that can close the gate on pain, preventing messages from other fibres getting through.

Question 50

Proprioceptive senses

Answer 50

Register body position and movement.

Question 51

Vestibular sense

Answer 51

Provides information on the position of the body in space by sensing gravity and movement in inner ear - semicircular canals and vestibular sacs - to crebellum and temporal cortex.

Question 52

Kinaesthesia

Answer 52

Provides information about the movement and position of the limbs and other parts of the body relative to one another.

Question 53

Perceptual organisation

Answer 53

Organisation and interpretation of sensory experience.

Question 54

Form perception

Answer 54

Organisations of sensations into meaningful shapes and patterns (percepts).

Question 55

Principles of form perception

Answer 55

Gestalt psychologists described figure-ground perception. similarity, proximity, good continuation, simplicity and closure.

Question 56

Recognition by components

Answer 56

Objects in environment are perceived and categorised by breaking them down into component parts.

Question 57

Depth perception

Answer 57

Organisation of perception in 3D based on binocular and monocular cues.

Question 58

Motion perception

Answer 58

Perception of movement by calculating motion from the changing image on the retina and using information from eye muscles’ movements of eyes.

Question 59

Perceptual constancy

Answer 59

Organisation of changing sensations into stable percepts. Three types of contancy are colour, shape and size. Can result in perceptual illusions.

Question 60

Perceptual interpretation

Answer 60

Generating meaning from sensory experience. Nervous system has innate potentials but some require environmental input to develop.

Question 61

Bottom up processing

Answer 61

Processing that begins with raw sensory data that feeds to the brain.

Question 62

Top down processing

Answer 62

Begins with observations, expectations and knowledge. Both happen simultaneously.

Question 63

Perceptual set

Answer 63

Perceptual expectations created by experience with the environment. Aspects of perceptual set are current context and enduring knowledge structures called schemas. Motives can also influence perceptual interpretation.

Question 64

Schemas

Answer 64

Organised knowledge about objects, people and situations.

Question 65

Direct perception

Answer 65

We automatically recognise the memory of well organised stimuli.