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percep 2B lec 1-3
perception lec 1-3
| Term | Definition |
|---|---|
| optic array | spatial dist of light, determined by positions of light sources and reflectors of light (objects) |
| visual encoding | - Light (wavelength + intensity) - Storage |
| Structure of vis syst | light > eye > retina > optic chiasm > LGN > striate cortex > extrastriate cortex |
| optic chiasm | - decussation point = info from right goes to left half of brain + vice versa) - no binocular neurons |
| encoding principles | - princip of least commitment - princip of leas redundancy - princip of graceful degradation |
| Principle of Least Commitment | Not lose info might need later on |
| Principle of Least Redundancy | Encode info as effish as poss |
| Principle of Graceful Degradation | If part of system breaks, should still be able to use it |
| Retina | - Light sensitive sheet at back of eye - where rods + cones found (photoreceps), bipolar + amacrine cells, ganglion cells, optic nerve |
| Receptive Field | - Region of retina that when stimulated infl firing rate of neuron - Pattern that is schematic of what neuron does |
| phototransduction | - Turning light into electricity through photons of light absorbed by pigment molecs which isomerise to pass on elec signal |
| Photoreceptor | - Diff receps = diff spectral sensitivities - Retain info abt wavelength content of light by diff activation of LMS cones - Can be fooled, lots of diff lights that stimulate same colour |
| Spectral Sensitivity | - S = short - M = medium - L = long Rods = single spectral sens |
| Visual Electrophysiology | - Experiments - Tiny electrode placed close to or in vis neuron - Visual stim presented to animal (anaesthetized, paralysed= - Record signals from neuron |
| Retinal Ganglion Cell | - Responds w spike train - More stim from more interesting/intensity edges - Responds to contrast btwn centre + surround - Colour + intensity edges |
| Spike Train | - Aciton potential = electrical activ send message down nerve - Spike = action potential - Spike train = response rate of neuron, series of nerve impulses |
| Centre/Surround Structure | - Of ganglian cells - Excitatory centre, inhib surround |
| Lateral Geniculate Nucleus (LGN) | - 6 layers - Some layers from contra some from ipsilateral side of head - Contra = 1, 4, 6 - Ipsi = 2, 3, 5 - Retinotopic organisation, map of retina - Neurons = centre surround receptive fields - regulate info flow from ret to cort |
| Optic nerve | - Cable that carries signals to comp that is brain - Convert light into elec signals - L + M = achromatic channel - L vs M = red-green channel - (M+L) vs S = blue -yellow channel |
| Retinotopy | - LGN, V1, optic nerve channels encoding = retinotopic |
| M, P & K Cells | - Parvo = midget/P ganglion cells = fine detail, red/green - Konio = bistratified ganglion cell/K cell = blue/yellow - Magno cellular layers = parasol ganglion = fed into by M cell = fast temporal changes - on optic nerve |
| V1/Striate Cortex/Primary Visual Cortex | - striate = stripey - 1.5 mill axons from LGN - contains 250 mill neurons - 6 layers, diff from LGN - receptive field = type of neuron (simple, complex, end stopped cells) |
| simple cells | elongated, orientation sensitive (orientation of light) |
| complex cells | direction + orientation selective |
| End stopped cells | length tuned, respond to short but not long bars, moving angles + corners |
| Hierarchical Structure | - Huber + wiesel - LGN and retinal ganglion = centre surround - Elongated receptive field of simple cell = centre surround responses added up (4 centre surround = 1 simple cell) - Complex cell = 4 simple cells added |
| Encoding in v1 | - Retinotopic - Orientation (angle + posish of smthn) - Spatial freq = size of vis feat - Binocular disparity (diff of posih btwn receptive fields in 2 eyes) - Motion (complex cells) - Colour |
| Extra-Striate Cortex | - receptive fields = bigger + more specialised - retinotopic posish less imp - v2 = colour, form, depth - v3 = motion, form - v4 = colour, shape - v5/MT = complex cells joined, partic direc of mosh - IT/FA = faces - MST = mosh in depth |
| Dorsal/Ventral Pathways | - Areas in exstri cortex = divided into pathways - dorsal = higher up in brain, parietal, controls action, involved in feeding in motion system Ventral = lower, temporal cort, percep + identifying objects |
| Scene Perception | - view of real world environ - mult objects + backgrnd elements - objects organised in meaningful way relative to each other + bckgrnd - Acted within |
| Object Perception | Objects = acted upon |
| Natural Scene | natural in sense that it comes from real world, can have man made objects |
| Gestalt Rules | - grouping rules - Whole is greater than sum of parts -Combine elementary feats into extended contours + shape - proximity, similarity (clr), good continuation |
| Good Continuation | - Hidden shapes = continuous as opposed to two diff shapes - Lines going same way = connected - more likely to perceive continuous as opposed to jagged lines |
| Elongated contours | - v1 simple cells detect bars + edges, small = fine detail, big = course detail - join simple cells = favour elongated contours (joined end wise wxcite each other, joined right angles inhibit each other) |
| Perceptual Segregation | - Distinguish objects in a scene - Figure/ground segragation = understand what is in foreground + what is background - Smaller = usually foreground - Observers discrim details more accurately in foreground |
| Illusory Contours | - Inferred contours, lines based on other objects - V2 - Kanicza triangle (eg of illusory contours, 3 pacmen + 3 chevron lined up) |
| Object Categorization | - Superordinate lvl = vaguest = animal - Basic lvl = most common = dog -Subordinate = most specific = border collie |
| Viewpoint Invariance | - How are objects encoded/stored - 3D model vs mult snapshots - 3D = object rotated in head and interpd from diff angles - Snapshots = snapshot mems of diff angles of objects |
| Scene Gist | - General description of a scene - Available after fraction of sec |
| Global image features | - Degree of naturalness (natural vs man made) - Degree of openness (horizon vis?) - Degree of roughness (many or few objects) - Degree of expansion (looking into dist or not?) - Colour (are colours characteristic of given locash) |
| Perceptual Inference | - What expected from a vis scene based on experiences of world - Assumptions abt identities of objects in scenes based on size + placement - Inferences can affect our judgements |
| Superstitious Perception | - Gosselin + schyns 2003 ○ Look at pics of vis noise + told there was an S shape, in reality, no S shape ○ Diff ppl = diff patterns of S (diff font) - Holy toast (virgin mary's face on toast) |
| Cognitive Toponymy | - Science of place names, names = often based on way they look - Eg: cobbler/ben arthur |
| Inferetemporal cortex | face processing |
| TE, TEO | - subregions of IT - At end point of ventral/what stream |
| Fusiform Face Area (FFA) | face percep |
| occipital face area | face percep |
| visual word form area | specialised for words |
| Diagnosticity | - Essensh vis feats that distinguish and object from other objects |
| Grandmother Neurone | - Horris barlow =neuron responds to granny - Most say no, not just one neuron responds when see perosn, it’s a bunch that respond to diff feats + combine (one resp to hair, one resp to eyes) |
| Jennifer Aniston Neurone | - Neuron that responds only to pictures of aniston |
Created by:
melissa.sjolin