Perception terms midterm #1

adaption

reduction in response caused by prior or continued stimulation

perceptual priming

change in perception due to exposure to a previous stimulus

sensory transducer

receptor that converts physical energy into neural activity

nativism

the mind produces ideas that are not derived from external sources

dualism

there are two distinct principles of being in the universe; spirit and matter

monism

mind and matter are united in a signal ultimate substance

idealism

reality is indistinguishable and inseperatable from human perception

reality is a mental construct

materialism

physical matter is the only true reality

the mind can be explained in terms of matter

empiricism

experience is the only source of knowledge

panpsychism

all matter has consciousness

psychophysics

science of defining quantitative relationships between physical and psychological/subjective events

just noticeable difference

JND

difference threshold

smallest detectable difference between two stimuli

minimum change in stimulus that can be correctly judged as different

two point threshold

minimum distance between two stimuli that can be distinguished

Fechner’s Law

magnitude of subjective sensation increases proportional to the logarithm of the stimulus intensity

absolute threshold

minimum amount of stimulation necessary for a person to detect a stimulus 50% of the time

method of constant stimuli

stimuli presented range from rarely to always perceivable, respond with yes/no

stimuli presented are rarely to always perceivably different from standard stimulus (more/less adj.)

method of limits

dimension of a stimulus is changed incrementally until participant responds differently

difference between two stimuli is changed incrementally until responded differently

method of adjustment

participant changes dimension of a stimuli or the different between two stimuli until they can detect a difference

magnitude estimation

assign values based on perceived magnitudes of stimuli

cross modality matching method

matching intensities of sensation from unrelated stimuli

ex - matching brightness and loudness

Steven’s Power Law

magnitude of a sensation is proportional to the stimulus’ magnitude raised to an exponent

signal detection theory

quantified the response of an observer to the presentation of a signal in the presence of noise

false alarm, correct rejection, hit, miss

doctrine of specific nerve energies

the nature of sensation depends on which sensory fibers are stimulated, not how they are stimulated

vitalism

a special/vital force drives living organisms

Hodgkin Huxley cycle

electrochemical process involving Na+ and K+ moving in/out of the neuron

accommodation

ciliary muscles change the shape of the lens, altering its refractive power

opsin

light sensitive protein

absorbs light of a specific wave length

myopia

image converges in front of the retina

hyperopia

image converges behind the retina

emmetropia

image converges on the retina

fundus

dark spot observed when looking at an eye through an ophthalmoscope

houses the fovea

duplex retina

able to have day and night vision

presence of both rods and cones

astigmatism

different refractory values vertically and horizontally due to having a non-spherical cornea

scotopic vision

black and white vision

only rods are functioning

photopic vision

colourful vision

only cones are functioning

mesopic vision

combination of colour and black/white vision

both cones and rods are functioning

chromophore

captures photons

rhodopsin

visual pigment found in rods

contributes to scotopic/black&white vision

graded potential

potential depends on amount of phots hitting the receptors, not simply a photon hitting it

lateral pathway

horizontal cells and amacrine cells

diffuse bipolar cell

receives input from rods and peripheral cones

input from multiple photoreceptors

high sensitivity, low acuity

midget bipolar cell

receives input from a single foveal cone

high acuity, low sensitivity

midget ganglion cell

parvocellular ganglion cell

p ganglion cell

sustained, sensitve, smaller, finer

parasol ganglion cell

magnocellular ganglion cell

m ganglion cell

transient response (change in light), insensitivity to colour, large receptive field, coarse spatial resolution

ON centered cell

middle region is activated by light and outer region is deactivated

bipolar or ganglion

OFF centered cell

middle region is deactivated by light and outer region is activated

bipolar or ganglion

lateral inhibition

horizontal and amacrine cells interact with vertical pathway cells and allows them to be more sensitive to contrast

concentric

ganglion cells have ________ receptive fields

contrast

sensitive to differences in light intensity

less interested in ambient light intensity

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Mach bands

illusory edges

pupils

can go from 2-8mm

16-fold improvement in sensitivity

abundance of photopigments

can detect photos easier, more sensitive

occurs in darkness

bleaching of photopigments

less sensitive, harder to detect photons

occurs in light

amacrines

during the daylight ______ cells care inhibited

retinitis pigmentosa

hereditary disease involving progressive death of photoreceptors and degeneration of the pigment epithelium

gabors

sine wave within a circular contrast function

cycles per degree

number of dark/bright bars seen per 1 degree of visual angle

0\.017

1/60

minimum visual angle to detect a cycle of grating for a normal eye

fourier transform

breaks down a function/image into sine waves of different frequencies

spatial frequencies

SF

visual images can be decomposed into since waves with different ________

number of cycles of a grating per unit of visual angle

acuity

smallest spatial detail that can be resolved

aliasing

signal is not reconstructed correctly, detail is missing from the original signal

Snellen test

block letters with strokes 5x its size used to test vision

contrast sensitivity function

CSF

relationship between contrast and spatial frequencies

harder to see spatial frequencies at a low contrast

heteronymous

different detects for the two eyes

homonymous

same defects for the two eyes

hemianopia

half the visual field is blind

quadrantanopia

a quarter of the visual field is blind

scotoma

small visual field defect

lateral geniculate nucleus

LGN

6 layered structure present in both hemispheres where ganglion cells synapse

2, 3, 5 is from ipsilateral (same) eye

1, 4, 6 is from contralateral (different) eye

topographical mapping

retinotopic mapping

neighbouring points in the visual field are projected onto neighbouring patched of neural tissue (LGN, V1)

cortical magnification

the fovea gets greater representation on neural structures compared the peripherhy

orientation tuning

neurons in the striate cortex respond optimally to certain orientations and less to others

simple cells

respond to edges or bars of a certain orientation in a certain part of the visual field

complex cells

do not have clearly defined exhibitory/inhibitory regions

phase-insensitive

prefer moving stimuli

have large receptive fields

magnocellular system

layers 1 & 2 of LGN

high luminance sensitivity, motion/flicker

parvocellular system

layers 3-6 in LGN

high spatial frequency, colour

koniocellular system

layers within the LGN 6 layer system

end stopping

cells in the cortex increase their firing rate as the bar length increases to fill up its receptive field, then decreases as the bar leaves there receptive field

seen in both simple and complex cells

ocular dominance

LGN cells response to one eye or the other

striate cortex cells respond to inputs from both eyes, but has a preference for one eye

column

vertical arrangement of neurons

cells have the same preferred orientation at different depths in V1

hypercolumn

1mm block of striate cortex with all machinery necessary to look at everything

all orientations preferences are found within 0.5mm laterally

CO blobs

systemic columnar arrangement of V1 discovered through cytochrome oxidase straining

title aftereffect

adapting to a pattern of a given orientations allows the perceptual illusion of tilt

Zöllner illusion

local tilt causes global tilt

dorsal stream

processes *where* information

fast & colour blind

ventral stream

processes *what* information

contains LOC, PPA, FFA, EBA

superior temporal sulcus pathway

processes biological motion and social perception

lateral occipital complex

LOC

responsible for object recognition

parahippocampal place area

PPA

responsible for recognizing scenery and locations

fusiform face area

FFA

processes and recognizes faces

also used to recognize things you are a specialist in

extrastriate body area

EBA

recognizes and processes bodies

perceptual committee models

middle vison is like a collection of specialists for a certain feature who vote on their opinion

pandemonium model

used to explain the parallel processing of letter recognition using demons

demons represent neurons at different levels of the brain, each responsible for detecting a certain feature

middle vision

combines features into objects resulting in perception

object recognition

matching perceived object representations to a representation in our memory

figure ground assignment

determines that some regions in a scene/image belong to the object in the foreground while others belong to the background

uses Gestalt principles of surroundedness, size, symmetry, and parallelism

relatability

the degree to which two line segments appear to be apart of the same contour

global superiority effect

properties of a whole object take precedent over parts of the object

recognition by components

RBC

objects are recognized by the identities and relationships of their geons/component parts