Lecture 4.docx

Lec 4 Most of the visual field we see from both eyes, closer to the peripheries its contralateral Nasal parts of the eye crosses over Short answer? Hetero hemianopia outer side of visual fields aren’t there, has to do with optic chiasm Contrast sensitivity concept: upside down ushape curve spatial frequency on x axis and on the vertical axis is contrast sensitivity More centrered to contrast, higher sensitivity, curve means at a certain range 60cpd at some point we cant resolve spatial frequencies anymore -there is a limit to see lower frequencies diff frequencies, degrees to which we can resolve diff contrasts in the world object perception: process that pieces things together, simple emelemnts into a cohesive structure, being able to perceive and object as an entity -object recognition: associates what you perceive with what you have seen before. Memory plays a role, recognizing things in term of memory. Perception and memory make up recognition -object identification: made a connection to a specific example, particular object -object naming: associate a perceive image with a function and characterize it by a name -how do we store info in a successful way, semantic labels -linking edges into contour-gestalt laws Edge in vision -neuron with large receptive field, can respond to large gaps and expect a continuous line -if gap is meaningful, have to 2 discontinuous lines they will not join together -perception is the sum of atoms of sensation, structuralism ahs to fail, retina cant tell diff between imcomplete object and complete -cant piece together info from retina to see something we can use certain rules Rules for linking contours -gestalt: whole is greater than sum of it parts -cant piece ind elements together and that’s all Grouping laws: set of rules that describe elements in an imge Good continuation:2 elements tend to group together if they lie on the same contour, lines that tend to be continuous -neurons are interconnected so tgose on continuous talk to each other, they enhance activity, the one not on the continuous is inhibited by the others -neurons fire more saliently helps us see as a whole -cant really measure smoothness, if you don’t see things as continuous that can be a test for smoothnes -things that belong together have a certain degree of smoothness Filling in gaps: illusory contours we are good at filling in gaps and seeing contours even though they are not there –kanisza -ability to fill in countour gaps - it is not a coincidence, the visual system tries to rule out coincidences -illusory contours make a difference fairly late, compared to what the visual field can do, with feedback you get illusory contours Texture segmentation: being able to piece together things and the surface, texture helps us bind stuff together -gestalt law of similarity: 2 or more elements grouped together if they are similar could be by size as well Gestalt law of proximity: elemts group together depending on their proximity -lines may group together if they are parallel or symmetric Common fate: elements move in the same direction group together Synchrony: groups are together because stuff happens across time Common region: elements are perceived as a larger part of region grouped together Connectedness: things belong together when they are connected Pandemonium -brain is a parallel processing computer -we have something we call perceptual committee: specialists are specialized for certain visual features and they all get to vote on whats actually visual -have feature demons that are specific for certain lines (they represent neurons) -things actually work in paralelle and there are something like votes in higher levels of what you actually see, and you pick what is most likely Object ambiguity Committee rules  Honor the law of physics and biology: laws of physics- darker contrast at top looks inverted (concave) lighter contrast on top rounded out (convex)  Resolve ambiguity: your orientation of the necker cube may flip around, the li