Psych1011 WEEKS 9+10 Flashcards
Sensation and Perception
PERCEPTION
The brain’s interpretation of raw sensory input.
SENSATION
Detection of physical energy by sense organs which then send info to the brain.
ILLUSION
Perception in which the way we perceive a stimulus doesn’t match physical reality.
TRANSDUCTION
The process by which the nervous system converts an external stimulus (like light or sound) into electrical signals within neurons.
SENSE RECEPTOR
Specialised cell responsible for converting external stimuli into neural activity for a specific sensory system.
SENSORY ADAPATION
Activation is greatest when a stimulus is first detected.
Level of sense receptor.
PSYCHOPHYSICS
The study of how we perceive sensory stimuli based on their physical characteristics.
Gustav Fechner, 1860.
ABSOLUTE THRESHOLD
Lowest level of stimulus needed for the nervous system to detect it, 50% of the time.
Lowest level of light, sound, etc.
WEBER’S LAW
There is a constant proportional relationship between the Just Noticable Difference and the strength of the stimulus.
→ The stronger the stimulus the bigger the changed needed.
Weber’s constant = K
K = ΔL/S
JUST NOTICEABLE DIFFERENCE
The smallest change in the intensity of a stimulus that we can detect, 75% of the time. Internet says 50%.
Also called Limen (ΔL)
SIGNAL DETECTION THEORY
Theory regarding how stimuli are detected under different conditions. Random or meaningful patterns.
David Green and John Swets (1966)
Response biases, signal-to-noise ration.
Possible responses-
Signal yes: true positive, false negative
Signal no: false positive, true negative.
MCGURK EFFECT
We integrate visual and auditory information when processing spoken language.
Audio = Ba
Visual = Ga
We hear “Da”
SYNESTHEIA
A condition in which people experience cross-modal sensations.
Hearing colours, etc.
Sir Francis Galton, 1880.
PARALLEL PROCESSING
The ability to attend to many sense modalities simultaneously.
BOTTOM-UP PROCESSING
Processing in which the whole is constructed from parts.
→ Perceiving an object on the basis of it’s edges.
→ Begins with activity in the primary visual cortex followed by association cortex.
Also known as data driven processing.
TOP-DOWN PROCESSING
Conceptually driven processing influenced by expectations and beliefs.
→ association then visual cortex.
Use of context.
PERCEPTUAL SETS
Set formed when expectations influence perceptions.
→ Young or old woman cartoon thing.
We expect to see something. Perception is an active process.
PERCEPTUAL CONSTANCY
Process by which we perceive stimuli consistently across varied conditions.
→ shape, size, colour.
SELECTIVE ATTENTION
Process of selecting one sensory channel and ignoring or minimising the others.
- reticular activating system.
- forebrain
Donald Broadbent - dichotic listening.
IN-ATTENTIONAL BLINDNESS
Failure to detect stimuli that are in plain sight when our attention is focused elsewhere.
- video with the guy dressed as a bear.
SUBLIMINAL INFORMATION PROCESSING
Subliminal perception
→ processing of sensory information below the limen (level of conscious awareness).
Subliminal persuasion = not effective.
HUE
Colour of light.
- white reflects all light, absorbs none.
- black absorbs all light, reflects none.
ADDITIVE MIXING
Mixing light.
All = white
Red, green, blue
SUBTRACTIVE MIXING
Mixing pigment.
All = black
Yellow, cyan, magenta.
SCLERA
Sclera = whites of eyes.
IRIS
Coloured bit of eyes. Controls how much light enters the eye.
PUPIL
Circular hole though which light enters the eye.
Closes when light increases or objects are coming towards us = pupillary reflex.
Dilated pupils = more attractive.
CORNEA
Part of the eye containing transparent cells that focus light on the retina.
Curved transparent layer covering the iris and pupil.
Doesn’t move or change.
LENS
Part of the eye that changes curvature to keep images in focus.
- transparent cells.
ACCOMMODATION (LENS)
Lens shape changes.
Flat = distant
Fat = close
MYOPIA AND HYPEROPIA
Myopia = nearsighted. Cornea too curved. Can see close, but not far. Hyperopia = opposite.
RETINA
Membrane at the back of the eye responsible for converting light into neural activity.
- some say actually part of the brain.
FOVEA
Central portion of the retina
ACUITY
Sharpness of vision.
RODS
Receptor cells in the retina.
Most plentiful. Long and narrow ("rods")
Basic shapes. Work in low levels of light.
No rods in the fovea.
Dark adaption.DARK ADAPTION
Time in the the dark before rods regain maximum light sensitivity.
Approx. 30 mins.
CONES
Receptor cell in the retina.
Less plentiful. Cone shaped.
Give colour vision.
Sensitive to detail, but need more light.
OPTIC NERVE
Axons of ganglion cells.
Blind spot = where optic nerve connects to the retina.
Most go to primary visual cortex.
Some go to midbrain, especially superior colliculus.
SIMPLE CELLS AND COMPLEX CELLS
In visual cortex.
Simple = response to specific slits, specific location.
Complex = specific slits, more locations.
→ Hubel and Weisel, experiments on cats.
FEATURE DETECTION CELLS
Cells that detect lines and edges.
Detect specific features.
Hubel and Wiesel - Nobel Prize
GESTALT PRINCIPLES
How we perceive objects as a whole within overall context.
- proximity
- similarity
- closure
- continuity
- symmetry
- figure-ground
FACE RECOGNITION
Lower part of temporal lobe.
PHENOMENOLOGICAL METHOD
Qualitative measurement.
- ask someone to describe an object.
CONVERGENCE IN THE RETINA
126 million rods and cones connect to 1 million ganglion cells.
Higher concentration of rods than cones.
Average 120 rods - 1 ganglion
6 cones - 1 ganglion
Within fovea cones 1-1 with ganglion.
LATERAL INHIBITION
Mach band illusion.
Helps define edges.
Cells in retina inhibit each other.
Can respond to certain patterns, etc.
TRICHROMATIC THEORY
Idea that colour vision is based on our sensitivity to three primary colours.
Blue, green, red.
Have 3 types of cones.
From 1800s.
COLOUR BLINDNESS
Inability to see some or all of the colours.
Monochromat - only 1 type of cone. No colour vision. Rare. Hereditary. Only rods, no cones.
Dichromats - 2 types of cones. Lots of colours, but trouble with red. More common, and more common in males.
OPPONENT PROCESS THEORY
Theory that we perceive colours in terms of three pairs of opponent colours.
Specialised cells. AFTER red/green/blue. Retina and LGN.
Red / green
Blue / yellow
Black / white
After images - visual cortex processing.
Hering, 1800s.
DEPTH PERCEPTION
Ability to judge distance and 3D relations.
Monocular and binocular depth cues.
MONOCULAR DEPTH CUES
Stimuli that enable us to judge depth using only one eye. - relative size - interposition - linear perspective - height in plane - light and shadow - texture gradient also motion parallax.
BINOCULAR DEPTH CUES
Stimuli that enable us to judge depth using both eyes.
1/2 axons in optic nerve stay same side.
1/2 axons cross.
Can compare.
- binocular disparity
- binocular convergence
BINOCULAR DISPARITY
Two eyes
- different information from objects that a near
similar information from objects that are far.
BINOCULAR CONVERGENCE
Eye muscles turn our eyes inwards to see nearby objects - convergence.
Brain uses this information to estimate distance.
PITCH
Corresponds with the frequency of a sound wave. Higher frequency = high pitch. Hertz (cycles per second). Humans can hear 20-20,000 Hz. Older people lose high pitch.
LOUDNESS
Amplitude (height) of the sound wave.
Decibels (dB)
Pain at 125 dBs.
TIMBRE
Quality or complexity of sound.
Human voices have different timbe. And musical instruments.
COCHLEA
Bony, spiral - shaped sense organ used for hearing.
Inner ear.
BASILAR MEMBRANE
Membrane supporting the organ of corti and hair cells in the cochlea.
ORGAN OF CORTI
Tissue containing the hair cells necessary for hearing.
OUTER EAR
Pinna - external ear
Ear canal - to ear drum.
MIDDLE EAR
Ossicle - 3 tiny bones.
Hammer, anvil, stirrup.
Transmit vibrations from inner ear to eardrum.
INNER EAR
Cochlea
Organ of corti
Basilar membrane.
Auditory nerve to brain.
PLACE THEORY
For high pitched sounds. Specific place along the basilar membrane matches a tone with a specific pitch. Membrane base = high pitch Membrane top = low ptch. Also matching in auditory cortex.
FREQUENCY THEORY
Low pitched tones.
The rate at which neurons fire the action potential reproduces the pitch.
100Hz volley theory.
THE BINDING PROBLEM
Refers to the process used by the brain to combine (or bind) the results of many sensory operations into a single percept. This occurs, for example, when sensations of color, shape, boundary, and texture are combined to produce the percept of a person’s face. No one knows exactly how the brain does this. Thus the binding problem is one of the major unsolved mysteries in psychology.
RETINAL RECEPTIVE FIELD
The receptive field of the ganglion cell, the region of retina over which we can influence the ganglion cell’s firing by light stimulation.
Excitatory and inhibitory areas.
NERVE
Axons of many neurons.
PROPAGATED RESPONSE
Action potential.
Once the response is triggered it travels all they way down the axon without decreasing in size.
Also remains the same size no matter how intense the stimulus is. But firing rate can increase.
NEURAL CIRCUIT
Groups of interconnected neurons. Can be just a few or hundreds or thousands.
SPECIFICITY CODING
Representation of particular objects in the environment by the firing of neurons that are tuned to respond specifically to that object.
ROD VS CONE DETAIL
Rods are more sensitive because have more convergence.
Cones have better visual acuity because they have less convergence.
HERMANN GRID AND MACH BANDS
Result of lateral inhibition.
SIMULTANEOUS CONTRAST
Our perception of the brightness or colour of one area is affected by the presence of an adjacent or surrounding area.
Lateral inhibition.
OSSICLES
Hammer, anvil, stirrup.
Convert vibrations in air (outer ear) to vibrations in liquid (inner ear).
INTENSITY
Changes the perceived brightness of colours.
Doesn’t change the hue.
SATURATION
Adding white to reduce the saturation.
Changes the hue.
Red becomes pink, etc.
WAVE LENGTH OF LIGHT
Determines the colour. Short = blue and violet Medium = green and yellow Long = orange and red
COLOUR OF OBJECT
Determined by the light they reflect.
Absorb other colours.
Chromatic = colour
Achromatic = no hue (white, black, grey)
SCALA TYMPANI AND SCALA VESTIBULI
Scala vestibuli = upper
Scala tympani = lower
Partitions in the cochlea. Basilar membrane and organ of corti are in between the two.
AUDITORY LOCALISATION
Azimuth = left right Elevation = up down Distance = how far or close NOT POSSIBLE FROM JUST AUDITORY, NEED TO LOOK AT IT TO DETERMINE DISTANCE Good at front. Less so behind and to the sides.
BINAURAL CUES
Slightly different sounds in each each (azimuth). Takes longer to get to further ear.
Also slightly different volume (azimuth).
MONAURAL CUES
Pinna calculate elevation. Where sound came from.
SLIGHT distance, but not really.
IDENTIFYING SOUND SOURCES
Not in vibrations, not in cochlea.
Auditory scene = the array of all sound sources in the environment.
Auditory scene analysis = separated into individual perceptions. Like watching a band. Can tell what sound is from singer. Guitar. Etc.
Apply heuristics, gestalt stuff, whatever.
Onset. Location. Similarity of timbre and pitch.
