Chapter 4: Sensation and Perception Flashcards
Psychophysics
study of the relationship between physical stimuli and sensation they evoke in human body
Transduction
The senses transduce physical energy into neural signals
that are sent back to the brain for further processing
Sensations
neural information detection in the brain from
the sensory organs (eye, ear, etc.)
where does perception happen
Realizing that we are seeing or hearing takes place at
brain, and not sensory organs
Data Reduction System
selecting and analyzing only most important data by the brain (we do not process everything)
Sensory adaptation
change in sensory receptor responsiveness towards unchanging stimuli e.g. pressure from wearing a watch
Absolute threshold
the minimum amount of physical energy necessary to produce a sensation
Difference threshold
the minimal difference between two stimuli required before the two stimuli can be coded as different
Sensory analysis
the process by which the senses divide the world into important perceptual features e.g. lines, shapes, color
Weber’s Law
Principle that two stimuli must differ by a minimum percentage to be perceived as different – depends on intensity too
Subliminal Perception
Detection of information below level of conscious
awareness
Subliminal Perception uses
To suggest or influence
Synaesthesia
One sense induces experience in another sense
Phantom Limb Pain
Experiencing sensations in a limb that does not exist
Occurs among amputees
Extrasensory perception (ESP)
- Perception in absence of concrete sensory input
Light
a form of electromagnetic radiation (aka electromagnetic wave
or energy) that is detected by the eye
Wavelength
– determines the nature of light i.e. hue or color. As an
example, red light has a different wavelength as compared to blue light
Amplitude
– tells us the intensity or brightness of the light
Structure of Eye
sclera, retina,iris,cornera,pupil,Lens
Sclera
- White, outer part of eye
- Helps maintain shape of eye
- Protects eye from injury
Iris
Coloured circular muscle that controls entering
amount of light
Pupil
Opening in center of iris through which light passes
* Size controlled by muscles in iris
Cornea
Transparent membrane covering front of eye
Lens
Transparent, somewhat flexible, disk-like structure
Retina
The multilayered, light-sensitive surface at the back of the eye
* Converts visual stimuli to neural impulses
Photoreceptors> Rods,Cones
Cells on the retina which convert electromagnetic energy into
electrochemical impulses – to be read by the brain
Rods
Photoreceptors for dim light
* Only produce black and white
* Function well under low illumination
Cones
Photoreceptors for colors and bright
light
*Require more light than rods
Fovea
Tiny area in the center of the retina at which
vision is best
* Highly dense with cones; rods
absent
Blind spot
Place on retina containing neither
rods nor cones
* Where the optic nerve leaves eye
Colour Vision Theories
Trichromatic theory
Opponent process theory
Trichromatic theory
The trichromatic theory that states we have 3 types of cones of varying lengths; red, green, and blue (sensitive to different wavelengths)
Opponent process theory
Opponent process theory: color vision theory based on three
“systems”: red vs green, blue vs yellow, black vs white
* Exciting one color in a pair (red) blocks the excitation in the other member of the pair (green)
After Image Effect
Fatigue caused by one response, will produce afterimage of the opposite colour
Colour blindness
– inability to perceive colours due to lacking or
faulty cones
Sound
vibrations/rhythmic movements in the air that are captured by the auditory system
Structure of Ear
3 main parts – outer, middle & inner
Outer
Outer – External part of ear that collects and channels sound
Middle
Middle – Channels sound to inner ear
Inner
Inner – Converts sound into neural impulses i.e. hair receptor cells within the cochlea that transduce vibrations
Frequency Theory
As pitch rises, nerve impulses of a corresponding frequency
are fed into the auditory nerve e.g. 800-hertz tone produces
800 nerve impulses a second
Place theory
Place theory – Higher and lower tones excite specific
areas of the cochlea e.g. higher tones are registered most
strongly at the base of the cochlea
Skin
Touch (pressure), temperature (hot/cold), pain
* Each with own specific receptors in the skin
Chemical Sense
Taste – sweet, salty, sour, bitter, umami (receptors in
tongue)
- Smell – receptors in the Olfactory Epithelium (roof of
nasal cavity)
Kinesthetic
– information on movement (kinesthesia) and bodily position (proprioception)
Muscle memory e.g. in playing sport & walking without
looking at feet
Vestibular
balance and orientation – semicircular canals (ear as an organ of balance and not just hearing)
- Motion sickness or dizziness – senses from eyes & ears
don’t match up (sensory conflict theory)
How sensations are organized into meaningful patterns
Pre-existing ideas and expectations guide our interpretations
Bottom-Up Processing
Bottom-up processing: analyzing information starting at the bottom (small units i.e. your senses) and going upward (to
the brain) to form a complete perception
Top-Down Processing
Top-down processing: pre-existing knowledge in mind that is used to rapidly organize features into a meaningful whole
Gestalt Principles of Organisation
change in focus also changes our attention towards other objects
Ambiguous stimuli
Ambiguous stimuli: patterns allowing more than one interpretation e.g.Rorschach test
Size & Shape Constancy
Perceived size and shape remains constant despite
changes in retinal image
Inattentional blindness
failure to perceive a stimulus that is in plain view but not the focus of attention e.g. driving accidents
Relative size
if two objects of the same size appear at different distances, the distant object looks smaller
Light and shadow
most objects are lit in ways that create clear patterns of
light and shadow, resulting in a three-dimensional appearance e.g. 3D drawings
Overlap
when one object partially blocks another, it appears to be closer
Perceptual habits
ingrained patterns of organization and attention – perceiving things as they usually are e.g. laptop model (Microsoft vs Apple)
Perceptual habits
ingrained patterns of organization and attention – perceiving things as they usually are e.g. laptop model (Microsoft vs Apple)
Perceptual habits
ingrained patterns of organization and attention – perceiving things as they usually are e.g. laptop model (Microsoft vs Apple)
Perceptual habits
ingrained patterns of organization and attention – perceiving things as they usually are e.g. laptop model (Microsoft vs Apple)
