PSY 200 Exam II Study Guide
PSY 200 Exam II Study Guide PSY 200
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PSY 200 Exam ll Study Guide Lecture 9 Visual Perception 1 Centersurround cells tend to not respond well to homogeneous light that covers both excitatory and inhibitory parts In areas where there is homogeneous light our neurons are hardly responding The centersurround cells throw away tons of information related to where the homogeneous light is covering The information from the homogenous light areas is from the edges that we perceive Percepts of the middle of an object are derived from the edges 2 Brightness Contrast Illusion When the centersurround cells are placed in the same position in the middle of the square they will both receive that same excitatory and inhibitory signals and thus give the same little response When the centersurround cells are on the corners of the squares one with a black border and one with a grey border the cells will receive the same excitation at the center of the cell But in the surround they will receive different amounts of inhibition The cell with the black surround will receive less inhibition and the cell with the grey surround will receive more inhibition Thus the visual system computes brightness as something like local contrast light relative to how much light is nearby Local contrast is a property of the centersurround cells Our percept of brightness is determined by the responses of cells at contrast edges As a result things that have equal physical intensities can look dramatically different In the example with the checkerboard the two squares are actually the same shade of grey The square that appears darker appears darker because it is surrounded by squares that are lighter than the square that appears lighter which is surrounded by squares that are darker The center surround cells are responding much more strongly to the edges surrounding the lighter grey square than they will for the darker grey square The centersurround cells are computing the contrast that causes the illusion El1eelsraIsl1atl w l cur hrs an guru quottart LE Fir1 H leie ear remade n gitW EEiu39rrjtl i Fl Fainluv 3 Herman grid illusion When we look at one intersection in the black Hermann grid white background we see whitegrey dots at the other intersections When we look at one intersection in the white Hermann grid black background we see whitegrey dots at the other intersections In the white Hermann grid when the centersurround cell is on an area between the intersections the center is lled with light and it has maximum excitation and some inhibition from the surround The centersurround cell in the intersection has an excitatory center but it has double the inhibitory signals from the surround If there is twice as much inhibition there will be a weaker response The cell at a street is going to believe it is brighter than the cell at the intersection That is why we see the streets as white and the intersections appear to be grey In the black Hermann grid there is a different type of neuron at play This neuron is excited by light in the surround and inhibited by light in the center Thus on the street there is less light in the surround and it is going to have a weaker excitatory response On the intersection there is double the excitatory surround and it will have a stronger excitatory response It is the same situation as the white grid except the neuron is reversed causing us to believe that the street is black and the intersections are grey We only perceive the changes at the intersections we are not focusing on because the area we are focusing on has a smaller receptive eld than the areas in our peripheral 4 Filling in Neoncolor spreading We see color and brightness inside objects so someplace in the brain must be lling in information from the edges to the interior of the object Sometimes this process gets messed up as shown in the watercolor effect If there is orange around the edges our brain lls in the information that the interior appears to be a light yellow color From the purple edges our brain lls in the information telling us that the interior is slightly light purple in color In reality the interiors are both white Our brain tells us that the colors are spread out through the interior CraikO BrienCornsweet effect Brightness information spreads across surfaces In the example the two grey patches appear to be different When the middle region is covered the left and right patches appear to be the same In the middle there is a difference but they fade into the same shade of grey towards the sides When the middle is uncovered we see it as two completely different shades of grey throughout each side In reality only the centers of the patches are different Our brain lls in the information telling us both patches are different throughout When the middle is covered however we are able to tell that they are in fact the same shades on the left and right sides Our visual system recognizes that one side is brighter and one side is darker and this information spreads throughout the whole surface even if the sides are the same 0 Disappearing pink circle If we carefully xate on the pink center it will start to disappear The yellow lls in the pink circle The disappearance of the pink circle is in our mind Our brain is sensitive to edges because of the center surround cells and it is difficult for the neurons to detect the presence of the edge If our eyes move it is easier to detect the edge If the eyes are steadily xated the neurons that would be coding the edge do not respond as strongly and they lose the information that there is an edge They instead ll it in with the edge they do recognize which is the edge between the yellow and black 5 Colorcompetition gateddipole circuit There is competition between opposite colors If you have a balance between green and red then neither color will win the competition nor will you see either green or red If there is an extra input to green green wins the competition and we see green But the synapse weakens over time and we see the fading of the green signal At the offset of the green signal there is a rebound of the red signal As the synapse recovers the strength of the green signal will equal the strength of the red signal and it will return to the initial state You cannot have reddishgreen because red and green are in competition with each other 6 Afterimages Green Red 0 Yellow Blue 0 Black White 7 Orientationcompetition circuit There is also competition between orthogonally tuned cells It is competition between cells in different orientations With additional input to the horizontal pathway the horizontal channel wins the competition and we see the horizontal orientation But as the horizontal gate habituates the horizontal signal weakens but is still winning the competition At offset of the horizontal input the gated horizontal signal is weaker than the vertical signal and a vertical signal rebounds As the horizontal gate recovers the system returns to the baseline and the vertical after response disappears Oriented reset signals are also implicated in an unusual type of afterimage When we see a horizontal input we have a vertical afterimage When we see a vertical input we have a horizontal afterimage Lecture 10 Visual Dynamics 1 The frequency of ashing at which subjects do not detect icker is called the Critical Flicker Frequency CFF The CFF is about 50 hz 50 onoff cycles per second and in 20 ms durations The CFF establishes minimum characteristics of electronic devices Lights icker at 120 Hz meaning that we are in darkness half of the time It is 120 Hz because it is the AC current We don t notice the darkness because the light ickers faster than the CFF and our brain cannot detect that we are in darkness for half of the time Computer monitors and TV s icker at around 60 Hz but better monitors go faster There is a gun that shoots energy at different places on the screen making the pixels glow Liquid Crystal Display LCD monitors work differently although some still icker The computer repeats and redraws the pixels on the screen at a rate of about 60 hz but it is too quick for most people to detect showing the CFF The phosphor on a computer screen typically glows for less than 10 ms The gun reactivates the phosphor every 17 ms Thus at any given time 13 of the screen is dark but the percept persists in our head Our brain lls in the times when the computer is dark 2 We see things in the world because the information about them persists in our heads We have this kind of persistence even after the light source with them has disappeared In an experiment by Bowen Pola amp Matin subjects adjust duration of a blank stimulus so the onset of the probe matched the perceived offset of the target In the experiment we have someone look at a xation point on the screen On one side a stimulus turns on and then turns off The subjects are supposed to make an adjustment to increase or decrease the timing between the physical offset of one stimulus to the physical onset of the other stimulus The idea is to adjust the timing so that the stimulus on the left appears to disappear just as the stimulus on the right appears This timing is called the interstimulus interval gives us an idea on how long the target stimulus must have lasted perceptually before the other stimulus became visible As the target s duration or luminance increases its persistence decreases A very brief stimulus seems to persist longer 3 Feedback in a neural network is important because it produces a persisting response The neurons continue to re action potentials even after the input stimulus has stopped In fact something has to reset the network or the response would persist forever When the neurons continue to re action potentials and remain excited the stimulus will persist until it is reset There are two possible mechanisms by which the network resets 1 new inputs inhibit old responses and 2 afterimages act as new inputs Afterimages get stronger as duration and luminance increase and as duration and luminance increase the persistence of the stimulus decreases As the target s duration or luminance increases the afterimage produced at the target offset increases in strength This means there is stronger inhibition to break the feedback and the persistence of the original percept decreases Afterimage strength increase D duration and luminance increase D persistence decrease 4 Masking Masking prevents us from seeing smears of objects as they move or as we move In the masking demonstration we are shown a matrix of letters and are asked to recall which letters we saw In the second part of the task the letters are replaced with black X s and we are again asked to recall which letters we saw When the letters are replaced with a matrix of black X s we are less likely to remember which letters we saw When there is no mask the stimulus from the letters persists in our brains for about 100 ms and we are able to recall more accurately what letters were present When the letters are masked with black X s the X s replace the letters in our memory and we have a more difficult time trying to remember the letters we saw The mask appeared after the target turned off and the target was presented for a brief period of time however our visual system us unable to develop a complete percept of a scene in such a period of time Thus the XXX mask interferes with the processing of the letters by shortening their persisting responses This is also what prevents the perceived blurring of changing scenes 5 Reichardt motion detector There are two separate regions on a Reichardt detector One region has a delay built in to the circuit They are two spatially distinct regions The signals have to reach the detector at the same time in order to have a good response One signal by itself will not trigger the response it requires both signals to reach the detector at the same time to trigger a response The detector responds to two signals moving in the right way in the right direction at the right speed If the motion is in the wrong direction or at the wrong speed the signals will reach the detector at different times and it will not trigger a response Humans have something like Reichardt motion detectors at lots of different positions in the visual eld because we are sensitive to lots of different motion directions and lots of different motion speeds They are like receptive elds that vary in both space and time and many aspects of how we perceive motion follow from the properties of Reichardt motion detectors 6 Apparent Motion vs Real Motion When objects move there is a continuous path of motion But Reichardt motion detectors do not require continuous motion and continuous paths are not necessary for motion to be seen The percept of motion depends on the 1 stimulus duration 2 interstimulus interval and the 3 distance between objects For a Reichardt detector to indicate motion the signal from the second area must follow the signal from the rst by just the right length of time We can vary the interstimulus interval between the stimuli which is the time between the offset of the rst stimulus and the onset of the second stimulus Apparent motion is the appearance of motion between two objects that are not actually moving rather they are simply being turned on or off Apparent motion is an illusory impression of smooth motion resulting from the rapid alternation of objects appearing in different locations in rapid succession Real motion is when objects actually move and there is a continuous path of motion Korte s laws of apparent motion state that to get good motion we need to increase the interstimulus interval lSl between the stimuli as the distance between them increased One conclusion of studies of apparent motion is that motion is a fundamental percept and it has an explicit representation in the visual system We can also be aware of something moving without actually seeing the movement 7 Motion aftereffect just like for color and orientation we might expect an aftereffect of motion There is competition between opposite directions of motion left right and up down The offset of one direction leads to rebound in the other When a stimulus in one direction is input we will see that stimulus until it is offset which we then see the opposite direction in the aftereffect Lecture 11 Attention 1 The world contains more information than we can fully interpret or process all at once The ability to deal with some stimuli and not others is attention It is not clear is there is an attentive system or if attention derives from other systems Modern theories see cognition as information processing much like a computer This is useful because it highlights certain limitations of what our brain can do Different systems have different capabilities capacities of information they can hold and speeds Necessarily some information is ignored because it is not processed within the time frame it is given The process of ignoring is attention that is we are limited in what we are processing because we are processing other information The selectivity is attention Part of attention seems to be due to 1 mental effort on your part attending a lecture or ignoring whispering around you part of attention seems 2 a natural side effect of mental effort ignoring the quotuhmsquot from a speaker and ignoring the feel of clothes on your body and part of attention 3 seems effortless a loud noise 2 Magic trick For the card magic trick we are asked to look at a set of cards and pick one card to focus on and memorize Then after the cards are shuf ed and shown again the card we have chosen has disappeared The magic trick is that whichever card we have chosen will disappear in the set of cards This means that the computer would have known which card we would have picked and that everyone chose the same card to memorize The trick is that none of the cards are the same they all have changed This makes it seem like everyone s card they had memorized disappeared The magic trick occurs because we are told to memorize one of the cards in the set When we memorize the card we are processing the card in mind and only partly processing the other cards Therefore when we see all the cards in the second set we assume that the cards were the ones we saw in the previous set and really believe that ours is the only one missing The reason this works is because there is partial processing of the other cards in the set makes us believe that the cards are the ones from the rst set This tells us that we have partial processing 3 Attentional paradox The attentional paradox arises from the idea that if attention strengthens perceptual representations we should lose perceptual veridicality the way things really are in the world It is the idea that when we focus on something we are strengthening it and when we ignore something we are weakening it but it is a paradox because we do not normally experience this For example when you look at a pair of red and green dots focusing on the red dot doesn t strengthen the red dot and weaken the green dot and when you focus on the green dot it doesn t strengthen the green dot and weaken the red dot This suggests that attention is not just strengthening or weakening the information about the environment Although sometimes attention can change perceptual properties But then we have an incorrect perception of the properties of the visual scene so it is dif cult to understand how attention is helping here Lecture 12 Attention 1 CogLab Attentional Blink experiment Subjects are shown a stream of letters presented one after the other at a very quick speed 100ms and we are asked to detect whether there is a J K both or neither in the stream of letters It turns out that the detection of the rst letter tends to make the detection of the second letter very dif cult if it immediately follows the rst The idea is that processing the rst letter uses up our attentional resources and it causes us to miss the second letter This idea is called the attentional blink The data for the rst target letter remains fairly constant The data is expected to show that as the number of letters between the targets increases the percent of the second target reported also increases As the number of letters decreases the percent of the second target decreases because we experience the attentional blink and miss the second target This experiement implies that detecting the rst letter causes us to miss the second letter It also suggests that processing the rst target letter uses up the resources that would otherwise be used to process the second target letter and that the attentional focus and refocus takes time and for this task takes approximately 400 ms 2 The attentional blink is due to the processing of information causing us to miss other information because our brain is using up the resources that would otherwise be used to process the other information 3 CogLab Visual Search experiment Time and type of processing can also be measured by having observers respond as quickly as possible when they detect a target It is hypothesized that tasks that involve attention will be slower than perceptually based tasks and it is expected that attention depends on the number of things that must be searched Typically we distinguish between a target and distractors by one or more features we vary the number of distractors and measure the reaction time In the coglab experiment we were asked to determine whether the target a green circle is present or absent in the scene The experiment tested our response time with four different searches feature present feature absent conjunctive present and conjunctive absent In the feature search it was easy to nd the green circle when it was presented with few distractors and when it was presented with many distractors In the conjunctive search it was still fairly easy when there were few distractors but it became more difficult when there were many distractors The data should show that the feature searches both when the target was present and absent should be fairly constant between the number of distractors and the reaction time with the response time for the absent target being a little larger than the response time for the present target For the conjunctive searches the data from the present and absent targets differ in their slopes The conjunctive search with the target absent is going to have a slope that is double the conjunctive search with the target present Therefore as the number of distractors increase the response time also increases but it increases to a greater extent when the target is absent in the scene When we have to attend to more stimuli it takes a longer time to process all of the information and our response time will be longer 4 The results are interpreted through feature maps These are maps that code for color and shape The maps tell us the color blue or green and shape square or circle of each target in the scene It allows us to determine if the green circle is present without requiring any searching Feature search can identify the target within either feature map but conjunctive search cannot identify the target within either feature map alone because it requires search by comparison across the feature maps A serial process takes time 5 The conjunctive search for a target that is absent has a slope that is twice as steep as the conjunctive search for a target that is present This is because when the target is present you nd it on average after searching half the items and then can stop the search For target absent searches we must search all of the items to verify each is not the target 6 Automaticity When a task is unfamiliar it seems to require a lot of attention to perform Later it requires less attention The process whereby a task goes from requiring a lot of attention to requiring little attention is called automatization Many tasks such as color naming and word naming are automatizable We can measure the effects by pitting an automatized task against a nonautomatized task 7 In the Stroop task we are asked to identify the color of ink for words being displayed It takes us longer to name the ink colors when the words are color names The word name interferes with ink color naming But ink color doesn t generally interfere with word naming Word reading is well practiced so it occurs quickly and is automatic whereas color naming is unpracticed so it occurs slowly and requires attention With two tasks both trying to report on a color the automatic one tends to mess up the unpracticed one and it takes more mental effort and time to do the unpracticed task Lecture 13 Sensory Memory 1 In a wholereport experiment subjects are asked to write down as many letters as they saw in a matrix For a wholereport experiment subjects report about 45 letters on average Subjects claim they saw more letters but lost the percept while they reported because they cannot report fast enough In a partial report experiment the same type of letter matrix is used but the subjects only have to report a subset of the matrix The row the subjects are supposed to report is indicated after the matrix disappears and the choice of row is random 2 In the experiment the subjects are shown a picture of an attentiongrabbing animation followed by a xation cross and then the presentation of a display of colored stars After one second neighboring pairs of stars disappeared When the stars reappeared one had a new color and the other remained unchanged lnfants recognized and look at the star that is changed and adults are able to report the location of the changed color item The infants show a preference to look at the changed object for small enough set sizes lnfant iconic memory is actually quite similar to adults Adults do better than the infants who did not understand the 39task The number of items in memory between adults and infants is similar 5 3 Masking effects can in uence iconic memory because persistencebased memory is very brief and is easily destroyed by a mask Therefore iconic memory is brief and easily disturbed With the mask you do not have enough time to focus attention on the indicated row lconic memory is so brief that it probably has little to do with normal memory and is too brief to be useful for many situations except maybe knowing how to reach for something just after the lights go out 4 Immediate Serial Recall In an immediate serial recall experiment subjects are given a list of items and must report them back with 1 no delay 2 in the correct order and with 3 no cues recall not recognition After this step the researchers plot percentage correctly recalled against position of item in the list 5 Iconic large capacity short duration brief easily disturbed Echoic smaller capacity longer duration seconds 6 In the visual presentation iconic memory of the last item is gone before the subject tries to report it poor recall In the auditory presentation echoic memory of the last item is still present when the subject tries to report it good recall Thus auditory presentation shows recency but visual does not 7 The suffix effect is the inability to recall the items at the end of a list when the list is followed by a word The suffix effect is found in auditory presentation only and the cue to report is either a word or a tone mask There is recency when the cue to report is a tone There is loss of recency when the cue to report is a word Words are physically different from tones so the suffix word acts like a mask to wipe out the last word in the list from echoic memory The situation is similar to being unable to report the letters in the partial report task with the Xmasks In order to avoid the suffix effect phone operators will speak prior to giving the number and then abruptly hang up after giving the number If they speak after the number is given the suffix effect will occur and we will forget the number Lecture 14 TwoStore Model 1 Ebbinghaus experiment This experiment measured how long it takes to learn a list of nonsense syllables perfectly Ebbinghaus took the list of nonsense syllables and studied them He then measured how long it took him until he could repeat the list of syllables in order without any errors Ebbinghaus wanted to answer the questions how long does the memory last in what form does the memory last how does it affect future behavior and does it help relearn the list at a later time Then after learning the lists of syllables he goes back and times how long it takes himself to relearn each list a different list each time Using the time it originally took him to learn the list and the time it took him to relearn the list he was able to calculate the savings If the savings equal 1 it means that his relearn time was zero meaning he didn t need to relearn the list perfect memory If the savings equal 0 it means that the relearn time remained equal to the original time he spent learning it subjects show no evidence of earlier learning When the savings are plotted as a function of time in days he graphed what was called the quotforgetting curvequot In the rst few days it takes signi cantly less time to relearn the list than it did originally However after 5 days the savings decrease dramatically It is important to note that the savings even after 30 days never goes to zero Ebbinghaus results suggest that memories can last a very long time in some form Memories were believed to be quotstoredquot in a memory system and did not just fade away and memory loss was believed to be due to interference of other memories Ebbinghaus experiment suggests that we are able to retain information for long periods of time in some form The longterm memory has a high capacity for information and can hold information for a long duration forever Peterson amp Peterson experiment BrownPeterson experiment You give subjects a trigram of consonants ask them to count backwards by 3 s and then tell them to report the trigram in order The duration of counting backwards is varied Numbers are different from letters so you might not expect any interference but they can actually have very strong interference This suggests that memories last only a few seconds The longer the retention interval the smaller the proportion of correct answers when asked to recall the trigram The results of the Brown Peterson study suggest that some aspects of forgetting are process driven This idea means that keeping a memory active requires effort If you are distracted by another task you cannot apply the effort to keep the memory The results of the Brown Peterson study also suggest that some aspects of forgetting are passive Even if you are distracted you can recall the trigram if only a short time has passed but if many seconds have passed while you are distracted you cannot recall the trigram Memory has decayed or something like decay while you were doing the distracting task Miller s memory span study This study tested how many items a subject can correctly recall immediately after exposure They have found that the magic number is 7 2 Miller examined shortterm memory tasks and found that typical subjects could hold about 7 items in memory at once whether the items were letters numbers or words He found that the magic number was 72 items can be held in the working memory at the same time Because we can only hold a certain amount of items in our memory for a short duration it is shown to be related to our short term memory STM The memory span experiment is one measure of working memory capacity In this experiment participants are given a list of items and asked to recall the list The list length is varied to see at what list length participants will make make few errors That list length is the memory span for that person on that task Individuals with larger memory spans can better keep in mind different stimuli and this seems to give them an advantage for a wide variety of cognitive tasks The very existence of shortterm memory is largely based on memory span types of experiments as it was noted that memory span was approximately seven items plus or minus two for a wide variety of stimuli This suggested a simple storage system that held approximately seven items Later studies demonstrated that memory span could be systematically in uenced by a variety of stimulus characteristics including the type of item These ndings have suggested that the capacity of shortterm memory is controlled by verbal processes The short term memory working memory can only hold 72 items at a time therefore if we are asked to recall a sequence of lights that is greater than 7 it is very difficult to do Modal model of memory The modal model of memory by Atkinson and Shiffrin asserts that the human memory has three separate counterparts sensory register shortterm store and longterm store It shows that there are multiple stages of memory The sensory register is where visual auditory and haptic information enters the memory The shortterm store also called the working memory is the component that receives and holds the input from the sensory register and longterm store It is the STM that plays a dominant role in active memory The long term store is the component that is the permanent memory store The model requires that there is transfer between the shortterm store and the longterm store When something is memorized items are rst held in the shortterm store as a temporary store and then the items may transfer to the long term store but this takes time to transfer When subjects are asked to recall items in a list we often remember the rst and last few items best The ability to remember items at the beginning of the list is called primacy The ability to remember items at the end of the list is called recency When the data from an experiment testing this is graphed we often get a ushaped curve In some situations the serial position curve can be explained by different properties of the shortterm memory and the longterm memory For the primacy effect we are using our LTM We are trying to remember what items were at the beginning of the list which requires effort in order to store At the end of the list we are showing the recency effect The items named at the end of the list are still in our STM so we are able to recall this items much easier Lecture 15 Working Memory 1 Types of searches a Parallel searching In parallel searching the target item is compared to all of the items in memory at the same time and the answer yes or no is returned after all of the items have been checked If this is the case the reaction time for both yes and no should be the same parallel In a parallel search the number of items doesn t matter and both responses will give a at line regardless of their answer b Serial terminating search In a serial terminating search the target item is compared to each item after the other and the answer is yes or no is returned after the target is found or all the items have been searched In a serial terminating search the reaction time for a yes is faster than the reaction time for a no For a serial terminating search you go through all the items onebyone until you nd the target Also the reaction time increases with set size and the lines have different slopes c Serial exhaustive search In a serial exhaustive search the target item is compared to each item one after the other The answer yes or no is returned after all the items are searched regardless of whether the target is found or not The reaction time is the same for a yes response and a no response In a serial exhaustive search we go through every item and then report the answer The reaction times increase with the set sizes but the reaction times increase the same for both yes and no The graph of a serial exhaustive search shows parallel lines but also show that the reaction time increases with increasing set sizes 2 The basic approach is simple Participants were shown a short one to six items list of numbers and asked to memorize them After putting them to memory a probe number was shown The probe number was either one of the numbers in the list or a new number The participant was to respond as quickly as possible indicating whether the probe number was in the list or not The response time of the participant should re ect the time spent searching STM to determine whether the probe number is part of the list By varying the number of items in the list Sternberg hypothesized that he could test several theories of STM search Sternberg39s data were consistent with the successive or serial search Speci cally he found that response times grew linearly with increases in memory set size For each additional item in the memory set participants took on average an additional 38 ms to make their responses Thus it seems the probe item is compared onebyone with each item in STM and each comparison takes approximately 38 milliseconds A second result was perhaps more surprising When he compared response times for probe quotPresentquot and quotAbsentquot trials probe item was in the memory set or not respectively Sternberg found no differences in response times This nding is notable because an quotAbsentquot response can be made only after all items in STM have been searched and found not to match the probe item At rst glance it might seem that a quotPresentquot trial could terminate as soon as the probe item is matched with the appropriate item in STM With a selfterminating search one would expect quotPresentquot trials to be faster but the data contradict this hypothesis The counterintuitive nding from Sternberg39s study is that search of STM is always exhaustive That is the cognitive processes responsible for searching STM for a particular item search through allitems in STM before reporting whether the probe item is in memory or not Exhaustive search makes sense if the search of the STM is done by some process that is very ef cient can search very quickly simpledumb it doesn t bother to stop itself and slow down the process and initiated by some other system a controller If it had to do a serial terminating search it may actually take more time to check each item instead of searching through all the items and then decide The controller is controlling the attentional system by supervising coordinating and startingstopping relatively independent processes In the experiment by Brooks there are two types of tasks These tasks are either visuospatial or phonological There are also two types of responses visuospatial and phonological In part 1 of the experiment spatial mental task subjects are shown a letter Then a star appears on a corner of the letter and subjects are supposed to classify whether the star is on a top or bottom corner If the star is on the top corner or bottom corner of the letter subject respond yes If the star is not on the top corners or bottom corners the subject responds no It is recorded how long it takes the subject to do the task In part 2 of the experiment verbal mental task subjects are supposed to read a sentence and categorize each word in the sentence as a noun or not by responding yes if it is a noun and no if it is not For each of the two tasks subjects are asked to respond either verbally or spatially Brooks then measured the time it took to nish each mental task for each response type diagrams pointing sentencepointing diagramsverbal sentenceverbal He found that when subjects have to respond by pointing it is easier to work with sentence information than diagram information and when subjects have to respond verbally it is easier to work with diagram information than sentencing information This suggests that there are two relatively separate systems One deals with visuospatial information and must do the pointing response and mental diagram task and the other one deals with verbal information and must do the spoken response and sentence task Working memory is an extension of STM that focuses on current thought and awareness It has a small capacity and it forgets information rapidly It is also a processor of information and not a storage device Lecture 16 Working Memory 1 Articulatory Control Process Phonological Store PS ACP Converts nonspeech Similar to how we rst information into speech code takes letters and converts it into speech sound described STM items decay from memory Refresh restarts the decay process Information available as spoken sound 0 Items not refreshed by ACP are lost Rehearsalrefresh 2 The phonological loop capacity depends on two factors duration before decay from the phonological store and the speed of rehearsal in the ACP The phonological loop suggests that it is not the number of items but instead their rehearsal duration That is to recall a list of items you must rehearse them all before any of them fade the duration of decay in the PS If the time needed for the items to decay is longer then they will remain in the PS longer before they need to be rehearsed by the ACP If they do not have to be rehearsed as often the phonological loop can introduce more items The greater the decay time the larger the phonological loop capacity The rate at which the ACP can rehearse the items is related to the loop capacity If the ACP can rehearse at a faster rate the phonological loop can have a greater capacity because the items are not lost in the PS 3 As you get older your oral reading rate increases This means that the ACP effectively increases your rehearsal rate as you develop This implies that it is not the loop capacity that changes overtime it is the rate of rehearsal from the ACP 4 Word length effect The memory span is larger for small words small number of syllables and smaller for large words large number of syllables That is as the number of syllables in a word increases the memory span decreases and as the number of syllables in a word decreases the memory span increases Also the reading speed rehearsal rate decreases as the number of syllables increase The inverse relationship is due to the rehearsal rate If the words are smaller the ACP is going to be able to rehearse them more quickly than if the words are larger 5 If a language is spoken more quickly the rehearsal rate increases If the language is spoken more quickly it should allow the memory span to increase Because the digits are being spoken more quickly the ACP is able to rehearse them more quickly and there is a greater loop capacity This affects measured IQ scores because part of the exam checks the memory span If someone who is bilingual would take the exam in English and then in Mandarin Chinese they would nd that they have a greater memory span when they took the exam in Chinese This is because Chinese is spoken much more quickly than English which increases the rehearsal rate and ultimately the memory span 6 In a study of articulatory suppression the subject seeshears a list of phonemes while they are repeating a phrase over and over The recall is worse for both auditory and visual presentation When you are repeating the phrase you are utilizing some of the resources of your articulating control process Because the ACP is tied up it is not able to effectively rehearse the information coming in and we are less likely to be able to recall the items 7 Phonological similarity The memory of a list of items is worse when the items sound the same All of the items are stored in the phonological loop and similar sounding items interfere with each other in the phonological loop Studies nd a phonological similarity effect for auditory stimuli under articulatory suppression Since the phonological similarity effect is there even when the ACP is not involved tied up in articulatory suppression it must be because it fades more quickly in the phonological store 8 Three groups of subjects recall consonants all with different backgrounds The group with no background speech had the best recall For the group that has nonsense words in the background they have the worst recall The group with noise bursts in the background had a recall somewhere in the middle The presence of phonemes in the background is critical to the irrelevant speech effect The information in phonemes just goes straight to the phonological loop and interferes with the items you are actually trying to hold in the phonological loop We are not necessarily distracted by the meaning of the sounds the mere presence of the speech sounds is enough to interfere with our ability to remember information Any words even foreign languages have a strong effect on our ability to remember information This is because the background phonemes interfere in the PS
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