Perception

heuristics are...

rules-of-thumb that can be applied to guide decision-making based on a more limited subset of the available information

The brain continuously makes predictions about the world and tests these against ______________

sensory evidence

the brain has evolved to __________

reconstruct reality in a way that is useful to us

one way to learn how a complex system is organised is...

by studying situations where it makes mistakes

mental life gets more complex with more ______

sensory stimuli

Define psychophysics

scientific method for investigation of relationships between physical stimuli and psychological experience

The "absolute threshold" is...

the smallest amount of stimulation needed for a person to detect that stimulus 50% of the time

Example of absolute sensory threshold: Vision

candle flame 30 miles away on a dark, clear night

Example of absolute sensory threshold: Hearing

a clock's tick 20 feet away when all is quiet

Example of absolute sensory threshold: Touch

a fly's wing falling on the cheek from 1 cm away

Example of absolute sensory threshold: Smell

a single drop of perfume diffused through an area equivalent to the volume of six rooms

Define difference threshold.

the minimum difference in stimulus intensity necessary to tell two stimuli apart

What is another name for the difference threshold?

just noticeable difference (JND)

What is the difference threshold or JND dependent on?

the magnitude of the stimuli

Weber-Fechner law:

CHANGE in INTENSITY over INTENSITY equals WEBER FRACTION (K)

Weber-Fechner law states that...

JND is a constant proportion of standard stimulus intensity

Weber fraction - light intensity

0.079

Weber fraction - sound intensity

0.048

Weber fraction - salt taste

0.083

Psychophysics marked the beginning of ___________

experimental psychology

Define signal detection theory.

a method of differentiating a person's ability to discriminate the presence and absence of a stimulus (or different stimulus intensities) from the criterion the person uses to make responses to those stimuli.

Hits are ______

identifying correct stimulus

A false alarm is when _______

subject identifies stimulus but there is no stimulus there

Light is ______

the visual part of the electromagnetic spectrum

Define visual acuity.

The ability to see fine detail

Visible light is ________

The portion of electromagnetic spectrum seen

Colour _______ exist in the outside world

does

Colour _________ exist in the outside world

doesn't

The lens of an eye expands and contracts to ____________

control how light falls on the retina

The optic nerve has ______

photoreceptors

There are no photoreceptors in the _________

blind spot

retinal image is ________ in passing through the lens

inverted

topographic meaning

map like -> reflects real world spatial relationships

visual signals relay to primary visual cortex via ___________

lateral geniculate nucleus

Receptive field

Region of sensory surface that, when stimulated, causes a change in the firing rate of that neuron

The visual system represents the world __________

Topographically

The basic elements within the visual world (e.g. edges, colour, movement) are delivered by ________

bottom-up hierarchical processes

feature detectors are _________

the building blocks of perception

Our feature detectors are wired to _______

detect changes

the brain can solve complex tasks by _________

breaking them down into many, much simpler sub-tasks

High-level phenomena can be understood in terms of _____

simple low-level mechanisms

motions perception is _______

relative

space constancy is __________

when we factor out self-generated movement, to perceive only movement arising in the world

motion is a powerful cue for __________

alerting, orienting and for form perception

perceptual constancies mean we can see real, unchanging properties in the world despite _____________

LARGE changes in stimulation

What does colour vision do for us?

1. helps us classify and identify objects
2. is important signalling mechanism in nature
3. facilitates perceptual organisation of scene into distinct objects

The colour of an object or substance is determined by __________________

the wavelengths of light that it reflects (or that pass through it)

There are two basic classes of ___________

Photoreceptor

What are the two basic classes of photoreceptor?

rods and cones

Modalities

sensory brain regions that process different components of the perceptual world

sensation

simple awareness due to the stimulation of a sense organ

perception

the organisation, identification and interpretation of a sensation in order to form a mental representation

transduction

what takes place when many senses in the body convert physical signals from the body into neural signals sent to the central nervous system.

D prime (D')

A statistic that gives a relatively pure measure of the observer's sensitivity or ability to detect signals

Sensory adaptation

sensitivity to prolonged stimulation tends to decline over time as an organism adapts to current conditions

retina

light-sensitive tissue lining thew back of the eyeball

accomodation

the process by which the eye maintains a clear image on the retina

Cones

photoreceptors that detect colour, operate under normal daylight conditions and allow us to focus on fine detail

Rods

photoreceptors that only become active under low light conditions for night vision

Fovea

an area of the retina where vision is the clearest and there are no rods at all

Trichromatic Colour Representation

the pattern of responding across the three types of cones that provides a unique code for each colour

colour opponent system

pairs of visual neurons that work in opposition

Area v1

the initial processing region of the primary visual cortex

topographic visual organisation

adjacent neurons process adjacent portions of the visual field

visual form agnosia

the inability to recognise objects by sight

affordances

potentials for possible actions by agents acting on the environment

binding problem

how features are linked together so that we see unified objects in our visual world rather than free floating or miscombined features

illusory conjunction

a perceptual mistake where features from multiple objects are incorrectly combined

feature integration theory

a theory that proposes that attention binds individual features together to comprise a composite stimulus

synaesthesia

the perceptual experience of one sense that is evoked by another sense

modularisation

the process of relatively encapsulated function

perceptual constancy

a perceptual principle that even as aspects of sensory signals change, perception remains constant

template

a mental representation that can be directly compared to a viewed shape in the retinal image

structural enconding

how a pattern is represented

monocular depth cues

aspects of a scene that yield information about depth when viewed with only one eye

binocular disparity

the difference in the retinal image of the two eyes that provides information about depth

motion parallax

a depth cue based on the movement of the head over time

apparent motion

the perception of movement as a result of alternating signals appearing in rapid succession in different locations

pitch

how high or low a sound is

loudness

a sound's intensity

timbre

a listener's experience of sound quality or resonance

cochlea

a fluid-filled tube that is in the organ of auditory transduction

basilar membrane

a structure in the inner ear that undulates when vibrations from the ossicles reach the cochlear fluid

hair cells

specialised auditory receptor neurons embedded in the basilar membrain

area a1

a protion of the temporal lobe that contains the primary auditory complex

place code

the cochlea encodes different frequencies at different locations along the basilar membrane

temporal code

the cochlea registers low frequencies via the firing rate of action potentials entering the suditory nerve

visual orienting

a behavioural response to move the eye towards a target

multisensory integration

the perceptual representation of events from more than one sensory modality

haptic perception

the active exploration on the environment by touching and grasping objects with our hands

referred pain

feeling of pain when sensory information from internal and external areas converge on the same nerve cells in the spinal cord.

gate-control theory

a theory of pain perception based on the idea that signals arriving from pain receptors in the body can be stopped, or gated, by interneurons in the spinal cord via feedback from two directions

vestibular system

the three fluid-filled semicircular canals and the adjacent organs located next to the cochlea in each inner ear

olfactory receptor neurons (orns)

receptor cells that initiate the sense of smell

olfactory bulb

a brain structure located above the nasal cavity beneath the frontal lobes

pheromones

biochemical odourants emitted by other members of their species that can affect an animal's behaviour or psychology

taste buds

the organ of taste transduction

neural coding of colour is an _______

opponent process

chromatic adaptation ___________

reduces our sensitivity to the dominant wavelengths in the light within our current environment

colour constancy

our tendency to perceive an object as the same colour, across changes to illumination