PSYC 339Lg WEEK 2 NOTES
PSYC 339Lg WEEK 2 NOTES PSYC 339
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This 12 page Class Notes was uploaded by Isaac Lemus on Monday September 5, 2016. The Class Notes belongs to PSYC 339 at University of Southern California taught by Justin Wood in Fall 2016. Since its upload, it has received 49 views. For similar materials see Origins of the Mind in PSYC at University of Southern California.
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Date Created: 09/05/16
PSYC 339Lg: Origins of the Mind Lecture Notes 8/28: Space Perception 2 ● Review of last lecture ○ Question: How do we perceive the rich three dimensional world in front of us? What are the process in our brains that we use and how did these traits develop? ○ Descartes: based off of innate reasoning ○ Berkeley: Based off of association and experience ■ Experiment: What happens to blind people’s vision after cataracts are removed? ● Conclusion: depends on amount of visual experience received ○ 50 year old many who just gained sight could not experience visual illusions ○ After 20 years you can develop the same visual abilities ■ Critical period don’t matter that much over visual experience ■ Problem: studying a person who has been blind for such a long time can be erroneous because their brain capabilities have been altered. The absence of one sense means that the other senses take over ● Today we will look at normal human adults ○ Can we shift around their visual perceptions? Would they be able to adapt to their new circumstances? ■ Helmholtz’s study: Walking through a forest with prism shifting glasses. ● If they can adapt= plasticity ● No adaptation= no plasticity ■ Results: Over time they could adjust. After they took the glasses off their brain took time to move them back to normal vision. The brain is actually changing to some capacity. Therefore he believes that space perception is flexible and able to be modified. If adults can learn then babies can learn and babies wouldn’t have to have innate mechanisms. So empiricism over nativism is definitely plausible. ■ BUT BUT BUT, there is a problem: Maybe it has to do, not with vision, but with where you think your body is. In other words, perhaps your vision isn’t the sense that is adjusting but rather, where you sense your arm is in comparison to everything else. When there is conflicting information being sent from two or more sense, touch (proprioception) is more likely to be affected rather than vision. ■ Conclusion: Space perception maybe isn’t modifiable and actually supports Nativism ● Study other animals ○ If the same abilities appear throughout many animals than humans most likely have it to ○ Gibson with the visual cliff experiment. Baby goats automatically know not to step of the goat when she was on the farm. ■ Experiment, A layer of plexiglass was placed on the floor and half of the floor was a three foot drop. Would a goat know not to walk of the “cliff”. Result; Not a single newborn goat went off the deep side of the cliff ● Not just goats! Goats, chickens, and lambs all have it since birth (they all can start walking at birth, there is likely a correlation) ● Rats and cats would avoid it after a week (once they learned how to walk) ● Humans after 6 months once they start walking around ■ Buuuuut a week for animals and 6 months for humans is a long time to wait to do this study. Babies and animals could learn about visual perception during the time they learned to walk ● We modified the experiment and raised two sets of animals in two different settings while they learned to walk: one in a light based group (normal) the other without any light or visual cues. ○ Results: Doesn’t matter if you are raised in the light or the dark, Once you can learn to walk you learn to avoid cliffs regardless if you are raised in light versus darkness ○ But okay cats, at first would go off the cliff but after three days of light they would learn not to do this.We theorized two possible options. ■ Specific effect of experience cat will learn through experience over the next three days that the cliff is safe. ■ Non specific experience- Being able to see turns on the innate capabilities of perception ■ So he ran a new test where the cats were automatically raised on the deepside of the cliff then would be shown the other side of the cliff. If it was specific effect, then the cat would stay on the deepside, because it is learned that it’s safe. If it is nonspecific, then the cat would see the deep end, and its innate process would determine that the shallow end is what is safer. ■ Conclusion: Cliff avoidance is still present and therefore nonspecific. ■ Next question: How does movement affect visual perception? ● Experiment: Held and heins experiment: cat locomotive. Two cats were attached to each other, one could move freely and associated their movement with the visual intake. The other cat couldn’t move and had to follow what the other cat did. ○ The cat that could move didn’t go off the cliff ○ The cat that couldn’t move didn’t associate their movement with their visual input. Went off the cliff 50% of the time ■ Strong evidence for nativism ● But i mean, it’s hard to transfer the results of other animals and say it’s true for humans. But it’s definitely plausible. Random definitions I need to know ● Homology: same mechanism across species. ○ Hox genes; genes that have stayed constant regardless of time. ■ Example: The Body structure of flies and mice are similar, you could put genes of a mouse in a fly (and vice versa) and the animal would turn out completely the same ● Convergence: opposite of homology Animals use different mechanisms to solve tasks ● Taking it into stalk: Visual perception is continuity over evolution ○ But all of these tests are the result of testing on other animals. Next class we will focus on human babies! Lecture Notes 9/1: Space Perception 3 ● Quick Review ○ Classic debate of Descartes (Innate abilities and that are reprogrammed, nativism) vs. Berkeley (Everything about the brain is learned, empiricism) ○ Studies of once blind patients ■ What we found: When they could see for the first time they couldn’t match the object with what they felt (Empiricism) ■ Vision seems to get better over time (empiricism) ■ Learning seems to depend on some sort of motion system that tracks what we move (Innate) ■ Critical period in stereovision (Innate) ○ Studies in normal human adults (glasses) ■ At first it seemed like visual perception does change, but in actuality the only thing that is changing is where we think our body parts are (Support for nativism) ○ Studies on newborn animals ■ Seem to have depth perception since day one (Nativism) ■ Same with babies (But we have to wait for them to start walking) ○ New experiment we didn’t get to: Cats in an only horizontally lined box for the first three months of their life lacks the ability to perceive depth because they never became accustomed to lateral lines ■ Nonspecific visual experience is necessary to set up visual perception ● Another words, they don’t actually have to experience cliffs to avoid them AKA nativism over empiricism ■ Environmental modification alters the cat’s visual perception ● Now lets try to study the visual perception of Babies ○ Problems: it takes 4.5 months for them to start walking, 7 months to start crawling and 3 years to start talking ■ To solve this, we examine where babies look at and for how long (to show preference) ○ Robert Frantz: Do babies prefer looking at bullseyes or vertical stripes ○ Babies like looking at faces, text, bulls eyes and not so much with homogenous colors. ■ This at least tells us they can see! But how well can they see? ● It takes 3 years for babies to obtain 20/20 vision ● There is a dramatic increase in visual acuity during the first half year and from there, there is only a gradual increase in vision capacity ■ Can they perceive depth? ● To test this: Do babies prefer to look at disks over spheres? ○ Anywhere 1 to 6 months- they would rather look at something that is 3D rather than 2D. But this supports both Descartes and Berkeley. ■ Descartes= Babies are perceiving 3D (Wow 3D!) ■ Berkeley= 3D effort, confusing, therefore attention ■ so existence of a preference tells us nothing about the reasoning. How do we go about distinguishing these? Helmholtz’s Caution is that just because continuity assumptions are possible that doesn’t mean they are correct. ○ Three ways to solve this problem ■ Looking for signatures of depth perception ● Stereopsis: putting together the two slightly different views of each eye to create the 3D perception we see AKA binocular disparity. We use this for everyday tasks like threading a needle. So to test this trait on babies, we put stereovision glasses on them (3D glasses) and showed them two images, one without disparity (would show up flat) The other with disparity (would show up in double imagines=3D). Results? At 3 months there is a dramatic increase in preference for the disparity imagines. But again, does this mean they can perceive depth or that the just like seeing double images? Well to fix this we tested for mature stereopsis signatures ○ Hyperacuity= babies prefer stereopsis version rather than just stripes ○ Limited range= if the stripes get too far apart, the perception of depth is lost of the baby ○ Horizontal disparity= babies only prefer disparities that are horizontal ● So in summary, babies have stereopsis like adults, it appears suddenly at 3 months and the trait comes before they are able to move or reach and develop spatial association….nativism ■ Putting together different cues to depth ● We showed babies two different cues for depth (motion-an object moving in front of another- and stereo-a triangle showing a shadow on the pattern below). And if babies perceived them as different it would support empiricist because it’s a new experience of depth, whereas if the baby thought they were the same, it would support nativism because it’s using innate cues to see the same thing, depth. Results? Babies only look longer if the depth arrangement has been changed but not between the two cues. ● So in summary, this supports nativism because empiricism would say that each cue would give off a new sensation in perception. ■ Size Constancy (Computation of depth) ● After showing newborn infants a small block close up, would they perceive a big block far away as new or the same thing (its retinal size would be the same). Results? Babies are able to perceive distance because they perceive each block as a novel experience. Supports nativism ● But even though this is probably nativism slanted, experience is still important, especially to maintain these abilities. Just because something is innate doesn’t mean it’s going to say rigid throughout a lifespan. ● Just to recap, here are the four categories we studied, try to summarize the main conclusions in each: ○ Blind patients ○ Normal adults wearing glasses ○ Studies of nonhuman animals ○ Studies for baby humans
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