PSYC 339Lg WEEK 3 NOTES
PSYC 339Lg WEEK 3 NOTES PSYC 339
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This 6 page Class Notes was uploaded by Isaac Lemus on Thursday September 8, 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 23 views. For similar materials see Origins of the Mind in PSYC at University of Southern California.
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Date Created: 09/08/16
PSYC 339Lg Lecture Notes 9/6: Navigation 1 ● Review: What did we learn from space perception? ○ Two different perspectives ■ Descartes: Nativism: Knowledge is innate ■ Berkeley: Empiricism: Experience builds associative learning ■ SO what side do the studies support? ○ First, we studied blind people who gained vision through their life. Results? ■ People rely heavily on experience to gain vision capabilities ■ This study supports empiricism but two things do seem innate ● Tracking objects. We all have the ability to discern objects once motion is added to them. Seems to be built into us ● Stereovision can never be developed. Can’t learn through experience. ○ Secondly, we studied adults with normal vision by altering perception. Results? ■ Vision seems to be rigid and unchanging (whereas our sensation of where our bodies are can be more easily changed) supports Nativism ○ Next, we studied newborn animals to see if they were born with these traits ■ Newborn animals instinctively know not to go off of a cliff ■ Supports nativism, but can this translate to humans? ○ Human infants ■ Infants too, know not to crawl of the edge once they can start walking ■ They also have the same signatures of stereopsis as human adults ● Hyperacuity ● Limited range ● Disparities need to be horizontal rather than vertical ■ Different cues can trigger depth ■ Can perceive the true size of object, therefore understand depth ○ All four areas point to idea that we have a core knowledge of space, which favors descartes and nativism. ● Now that we’re caught up, how exactly do we navigate the three dimensional world? ○ We are horrible at navigation on our own without landmarks or references ■ 1920’s study where people were blindfolded and asked to walk/swim forward. Results? We started out straight then we would veer off course dramatically ○ Geometric questions have been asked for thousands of years: Socrates states that geometrical knowledge is innate rather than learned. ■ Study on an un schooled slave: how do you double the size of the square? The slave figured it out and so socrates figured geometrical knowledge is innate. Obviously this study was primitive, but good start socrates. ● So here are the questions to focus on: ○ What are the origins of this geometric knowledge? ○ What aspects can change when it comes to geometric knowledge? ● Lets focus on animals and how they compare to humans ○ Do they/we use the sun and the stars to figure out how to get to one place to another? ○ What aspects of geo knowledge are built in to our brains and what part are learned? ○ What core mechanisms of navigation are constant through humans and animals ○ How to human go way beyond the capabilities of other animals ● Three systems that humans share with other animals. First is path integration! ○ Let’s start with ants! ■ They generally follow smell trails for navigation. But In the Tunisian desert, the wind and dirt wipe away the smell and there are no landmarks so how do they navigate? How do they figure out where home is after they find food besides going back the wandering trail from which they came from. They are somehow able to B line there way back home! ● Maybe the ant is looking for something we can’t see? An external cue? Or maybe the ant is doing some natural trigonometry? ● Experiment: we let an ant find food then we moved it over ten meters to the right without it knowing. Results? it walked home but was 10 meters shifted to the right, so they have fixed location in their head. How? ○ The sun seems to be used as a compass. But the sun moves across the sky. So the ants update their position by taking into consideration where the sun is in the sky ○ When the sun is covered, the ants can internally keep track of where the sun should be and then adjust when it comes back. ■ Three different hypothesis ● Maybe they have an energy cue like humans; the more tired they are the farther they must have walked. ○ Not the answer because when we added weights to the ant it still got home perfectly ● Maybe they use optic flow. If they’ve seen a lot of stuff means they’ve traveled farther ○ Not the answer, even if the ants eyes are covered, they can still navigate the right distance ● Maybe they count their steps, like an internal pedometer. A study added stilts to some ants and cut some ants’ legs in half. ○ Ants with stilts over estimated the distance ○ Ants with stumps underestimated the distance ○ Ants with no change made it back home perfectly ● In summary, for direction the desert ants use the sun, and they count steps for distance. ○ Now let’s look at bee’s ■ They use optic flow rather than counting the number of wing flaps ● Because wind could affect their distance on the way there and back ● Then they do a special dance to tell other bees the exact location of the food they found ● Take away from this, animals evolve to the best kind of strategies based of the restraints given to them ○ Since ants and bees have these computations, then maybe larger animals would have these too: ■ Gerbils would take off from their nest and babies for food and the scientist would turn the ground. ● The result is that regardless of where the noise of her babies are coming from, the gerbils went the wrong way because they were following their path direction ■ Geese on their first flight were first driven away from home. When they took of to fly they all went towards home. ■ Newborn chickens the chick will imprint itself to whatever it sees and will naturally stay close to this object. Even if barriers are in the way, the chick will know how to stay the closest to it. ■ Young children ● they took sighted children and a blind child and asked: Can you put the toy in the basket? They took a novel path, even the blind child did it. Doesn’t seems to be vision/experience based. ■ Adults also have path integration but first world cultures use it far less ● Experiment: people in rectangular room with different objects studied them as references then were blindfolded and: ○ Turned around with light on ○ Turned around with light off ○ Turned around with light off then turned on ● Results? The human adults need a compass like the heat of a light to determine where we are. ■ Conclude: Path integration is used with every single animal study in some way and it seems to be innate. ■ Is it a homology or is it a convergence? ● Most researches think this trait it a homology and was passed down by a common ancestor. Lecture notes 9/8: Navigation 2 ● Review of last class: we need some sort of geometric knowledge in order to navigate. But is this knowledge innate or experienced? ○ Three core processes: Yesterday was path integration. ■ We looked at ant and their ability to B line straight back to the nest after they have wondered for food. This same trait is shared by other animals like gerbils. This trait is so strong that the gerbil will ignore other cues. Newborn chicks who have never been separated from their imprint. Blind and sighted human children are able to create novel paths. Human adults need a sun or spotlight to keep orientation when blindfolded and asked to point to objects in a room ■ Path integration is powerful, but there is limits. ● There is 2 degrees of direction error and 10% of distance error ● Memory is involved, so after time passes, the path can be forgotten ● When it goes wrong we need other mechanisms, and that's what we're going to focus on today: snapshots representation: Viewdependent scene recognition. We create a vivid image in our head as a reference. This is in pretty much all animals. ○ Snapshots is one of two kinds of possibilities for navigation: ■ There is a map in our head and we continuously follow the right path ■ We store thousands and millions of snapshots in our head and we find a way to connect those snapshots together. No map, just a bunch of places that are linked together. ■ To solve this problem let's look at bumble bees ● Experiment: bees will go around an area and take snapshots before going to the food. Then you could release them from anywhere and they can B line straight to the food. For the case of Bees they don’t seem to have a map in their head. ■ Now let’s look at rats ● Water mazes once the rats know where the platform is, they can B line straight to it by going off of the shape and color references on the side of the pools. ● To test if this is snapshots, we tested on new rats but blocked of a section. Then when we put them on the new section they had no idea where to go until they made it to a familiar zone then went straight to the platform ■ Results? Animals seem to use snapshots, but what about humans? Well comparative experiments state that if a fundamental trait is present in a basic animal, then that same mechanism is likely to be in more advanced animals, humans in our case. ■ Now time to test humans; put objects on a table. Bring in participants, they look at table. Close eyes, one object is moved. Participants open eyes and can tell what objects are moved. ■ Now scientist move the table when the participants eyes are closed, humans are terrible at telling what , why? Because they never developed a snapshot from this position. ■ Young children can’t take in other people’s viewpoint on things ● 3 mountain doll experiment ■ Put humans in virtual maze, where scientist can create wormholes and destroy the laws of euclidean geometry ● People learn equally fast in both, and no one is aware of the wormholes. Supports snapshots. We don’t form euclidean maps. ■ Through rats experiments we learned that the hippocampus helps with memory and therefore navigation. Three different types of cells used in the hippocampus ● Place cell Does the snapshot part, fires when see a familiar perceptual image. we can connect the place cells together to navigate (like google maps street view) ● Direction cell acts like a compass. Will fire when body facing the right direction ● Grid cells Spatial organization seems to be a collection of triangles, will fire when the body meets a vertex of triangles. ● Are these neurons innate? Study on baby rats says yes ■ So do humans have these similar core systems in the same parts of the brain? We use FMRI to see what areas of the brain are more active during certain times . Our hippocampus becomes activated when when we see houses or scenery. After showing someone the same scene over and over again, peoples hippocampus becomes restimulated. We become aware when we want to create a new snapshot. ● Third core system: reorientation ○ Do we have mechanisms that reorientate ourselves and how do we do it? ○ Rats only use geometry (ignore patterns, colors, smells) and only look at the surface layout. Signatures of what makes them do this ■ Its domain specific it only operates over some areas and not others ■ Its task specific it only happens when you disorientate a rat ■ Encapsulation the information is still used in the brain but it's not used in the process of reorientation ○ Lets look at young children to see if they all have these same signatures ■ Hide sticker in rectangular room ● When all the walls are white they go to long corners ● When one wall is red they still go to the long corners ○ Completely ignore red wall ○ Domain specific because they go to long corners because of geometry of extended surfaces. ○ Task specific If the child isn’t spun around, the kid will go off of color. But if the child is disoriented it will base finding sticker off of geometry ○ Encapsulation the kids remember seeing the red wall. But doesn’t use the information ○ Is this trait innate? newborn chicks even show these geometric patterns but this is the only study so we can’t really know for sure yet whether or not this trait is innate ● But this can’t be the whole story, adult humans must have more than these core knowledges! ○ Adults can develop theory of mind for the three hill dol experiment ○ Adults can reference the red wall as a reference ○ We will look more into this next week!