psy 200 exam 2

How can we measure perceptual experience with the psychometric function?

Plots the proportion of times line without wings is reported longer than the line with wines
Perceptual experience is described in terms of physical units

Why does the inability of on-center, off-surround neurons to respond to homogeneous fields of light means our percepts of brightness are based on edges?

Characteristics of cell receptive fields force additional properties of the visual system. Center-surround cells tend to not respond well to homogeneous light that covers both excitatory and inhibitory parts. Because of this, percepts of the middle of an object is derived from the edges

How do the center-surround cells behave in the brightness contrast illusion? (Be able to explain the behavior of cells in at least two different positions and for two different stimuli)

The visual system computes brightness as something like local contrast. 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.

For example, when looking at 2 squares with the same color in the middle but where one has a darker square surrounding and the other has a lighter square surrounding, the grey in the middle of the light square looks darker. This is because at the receptive fields on the corner, the center surround cells receive the same excitation at the center but differ in the same amount of inhibition at the surround. The one with the dark surrounding square has less inhibition while the one with the lighter surrounding square has more inhabition

How the center-surround cells behave in the Hermann grid illusion and how does this behavior relate to the perceptual experience of the illusion?

This is related to on-center off-surround cells. Cells at the intersection receive more inhibition than cells at single roads. This is why it looks like there are fuzzy patches of black at the line intersections. These patches disappear if you try to focus on them because the receptive fields become smaller as you focus

The opposite (white background, black grid) has the same effect which tells us that there is a second type of cell (off-center, on-surround)

Explain the water color effect

Purple wiggle with a yellow wiggle following

Visual system fills in the area between the yellow edges as a muddy orange/yellow

Explain the O’Brien-Cornsweet effect

In the image, there is the same gray on the far right and far left but, the left gets slightly lighter as it moves towards the middle and the right gets slightly darker as it moves towards the middle. Because of this, it looks like a lighter gray on the left and darker on the right

Explain the disappearing pink circle illusion

If you carefully fixate the pink center and keep your eyes very still, it will disappear and the yellow will fill in. This is because there is a blurry line between pink and yellow and by fatiguing the neurons by staring, the only signals that remain are the strong ones (yellow with the edge)

Describe the color-competition (gated dipole) circuit that produces color afterimages

There is competition between opposite colors (both cannot exist in one pixel at the same time).

If you have equal inputs of opposite colors (ex. red and green), you see white and neither color wins the competition.

If there is more green inputs, green wins the competition and red is inhibited.

If you keep looking at the green thing, the synapse that keeps sending neurotransmitters to say you see green, has less and less to send so eventually the signal becomes weaker and weaker but it is still beating out the red

When the green is replaced by white, you get equal inputs of red and there aren’t enough green neurotransmitters so it loses to the red and the red inhibits it (at the offset of green, you see red).

Eventually the neurotransmitters regenerate and everything goes back to normal

Predict what color of afterimage you would see after looking at red

Green

Predict what color of afterimage you would see after looking at blue

Yellow

(not orange!!!)

Predict what color of afterimage you would see after looking at green

Red

Predict what color of afterimage you would see after looking at black

White

Describe the orientation-competition gated dipole circuit that produces oriented afterimages

Same as color-competition gated dipole

Opposite orientations compete with each other (competition between orthogonally tuned cells)

The offset of the horizontal leads to a rebound in the vertical

As horizontal gate habituates, horizontal signal weakens (It still wins the competition, though)

At offset of horizontal input, the gated horizontal signal is weaker than the vertical signal and a vertical rebound appears

As the horizontal gate recovers, the system returns to baseline and the vertical after response disappears

What is the critical flicker frequency?

The frequency of flashing at which subjects do not detect flicker is called the Critical Flicker Frequency (CFF)

About 50 Hertz (50 on-off cycles in a second)

20 millisecond durations

How does the critical flicker frequency relate to characteristics of some electronic devices?

Ex. some lights are not consistently on but flicker fast enough that it we don’t notice

Computer monitors aren’t constantly on, they flicker (better monitors flicker more quickly)

What is meant by persistence?

Persistence refers to the duration of the perceptual experience of the stimulus

Describe an experiment that would measure persistence

Subjects sit down at a computer screen and stare at a fixation point. On any given trial, an image appears on one side of the fixation point and turns on and off. A image appears (probe stimulus) on the other side of the fixation point and turns on and off

Subjects are trying to figure out if the target (first) stimulus disappeared before or after the probe stimulus appeared. This is tricky because it takes the visual system time to recognize that the target stimulus disappeared and that the probe stimulus appeared

Asked to report if the two stimuli are seen together

What experiment measured persistence?

Bowen, Pola, & Matin, 1973

What were the findings of Bowen, Pola, & Matin, 1973? How did duration and intensity of the stimulus affect results?

As the target’s duration or luminance increases, its persistence decreases

Weak targets last longer

How could excitatory feedback in a neural network be responsible for persistence?

Feedback produces a persisting response

Once the feedback loop gets going, it can be hard to turn off, leading to persistence

Explain how after-responses could shorten persistence caused by excitatory feedback in a neural network and how this relationship might explain the findings of the persistence experiment involving the duration and intensity of the stimulus

As the target’s duration or luminance increases, the afterimage produced at target offset increases strength so there is stronger inhibition to break the feedback so the persistence of the original percept decreases.

(Offset of input from the eyes produces an after response, inhibiting the persisting response)

What is meant by masking?

Masking is a term in perceptual experiments where a detectable stimulus (target stimulus) becomes undetectable by the presentation of a second stimulus (the masking stimulus) in close temporal or spatial proximity to it

How are masking effects related to persistence and performance for detecting very brief stimuli?

The mask appeared after the target turned off and the target was presented all by itself for a brief period of time. However, our visual system is unable to develop a complete percept of a scene in a such a period of time

Thus, the XXX mask interferes with processing of the letters by shortening their persisting responses and prevents perceived blurring of changing scenes

When the letters are replaced with a blank scree, your brain is still able to process the information shown even after the letters disappear due to persistence.

When an X mask is shown, it interferes with the processing of letters by shortening the persisting responses. The new information from the mask writes over/destroys the information from the letters and you no longer have access to it. This is why you remember things better without a mask than with a mask

Describe metacontrast masking

Metacontrast masking occurs when a target stimulus is followed by a masking stimulus, whose contours fit neatly around the contours of the target stimulus

In metacontrast masking the mask and target do not overlap in space and (often) in time

Describe the typical results of a metacontrast masking experiment

The timing between the target frame and the mask frame matters. If the SOA is 0 (target and mask appear at the same time), people do well. If you separate target and mask (60-90 ms), people do worse because the mask has the biggest effect on persisting signals.

If you make the mask much later (200 ms), it comes too late to have a big impact and performance starts to come up again

Describe the properties and behavior of a Reichardt motion detector

2 detectors for light/motion

The first detector has a delay while the second one does not.

The neuron they feed into is a coincidence detector, meaning that it needs stimuli from both detectors at around the same time to fire.

Reichardt detectors are only sensitive to motion of the proper direction and speed

Why is a given Reichardt detector sensitive only to motion of the proper direction and speed?

If motion comes from the other side, the signal from the detector with the delay gets triggered second so the signals will not hit the neuron at the same time.

If the motion is too fast or two slow, the signals also will not hit the neuron at the same time.

What is apparent motion?

An optical illusion in which stationary objects viewed in quick succession or in relation to moving objects appear to be in motion

How does apparent motion differ from real motion?

In apparent motion, the “moving” object is actually stationary whereas in real motion, the moving object is actually moving

Describe Korte’s laws of apparent motion

To get good motion, you needed to increase the interstimulus interval (ISI) between the stimuli as the distance between them increased

What is a motion aftereffect?

The motion aftereffect is a visual illusion experienced after viewing a moving visual stimulus for a time with stationary eyes, and then fixating a stationary stimulus. The stationary stimulus appears to move in the opposite direction to the original stimulus

Describe the circuit responsible for producing a motion aftereffect

Same as color- and orientation-competition gated dipole

Opposite directions of motion compete with each other

The offset of the “up” leads to a rebound in the “down”

As “up” gate habituates, “up “signal weakens (It still wins the competition, though)

At offset of “up” input, the gated “up” signal is weaker than the “down” signal and a “down” rebound appears

As the “up” gate recovers, the system returns to baseline and the “down” after response disappears

How is attention related to information processing and processing resource?

Cognition is like information processing in technology. If a system can’t process information fast enough, it looks like it’s not being attended to. Because of this, some information is ignored, simply because it wasn’t processed

How does not processing information differ from ignoring it?

If you’re ignoring something, you’re choosing not to pay attention to it. If you don’t process information, it just means that there was too much information with not enough time and your memory system was unable to work through all of it.

Explain the CogLab Simon effect stimuli

A red or green square either to the left or to the right of the fixation point

Explain the CogLab Simon effect task

Respond as quickly as possible to identify the color of the square. The square is sometimes on the left and sometimes on the right side of the screen (irrelevant). You respond with a keypress on the left (green) or on the right (red)

Explain the CogLab Simon effect findings

People are faster identifying color for congruent (left-green; right-red) than incongruent (left-red; right-green) conditions

About a 36 millisecond difference

Explain the CogLab Simon effect interpretation

The Simon effect is, in some sense, a failure of attention. You want to ignore the location of the target square and only attend the color but you cannot ignore the target location

What are the basic properties of the field of human factors?

Applied cognitive psychology
Among other things, design interfaces so that stimuli and responses are compatible
Products “feel” better, are used as intended, and users make fewer errors
Ex. doors (plate tells us to push, handle says to pull)

Describe the magic trick demo from class and explain how it tells us something about attention

Shown 5 cards and asked to attend to one. Slide changes and we are told that our card has disappeared. All card have slightly changed but you only notice a change in the card you were attending to

Even when you are looking at something, unless you are actively attending to it, it can be hard to notice changes (you don’t take all of the information in)

When attention is focused on one thing, you ignore other things

Describe the flashing images demo from class and explain how it tells us something about attention

Easier to see the changes when the pictures are flipped back to back. Harder to see the changes when one picture is shown, then a blank screen, then the picture that has been changed

This shows us that we cannot take in and process all of the information in our environment

In some situations, attention can be focused by certain stimulus characteristics, especially changes (flashes of light, movement, color, etc.) We depend on these characteristics a lot. Removing these cues can make simple tasks rather difficult

Describe a situation where attention changes perceptual experience. What is interesting/surprising about this?

Example: In a venn diagram with overlapping grey circles, when asked to attend to a certain intersection, the one you are attending to looks darker than the other ones only when you are attending to it

Describe the CogLab attentional blink experiment

On each trial of the experiment, a sequence of 19 letters was presented, with each new letter overwriting the previous one. Each letter was presented for only 100 milliseconds. Your task was to judge whether the letters J or K were in the sequence.

The independent variable in this experiment was the temporal separation of the letters. On some trials, only one target was shown. This is referred to as a separation of 0; because only a single target was shown, there was no temporal separation. On all other trials, both J and K were shown but were separated by different numbers of letters. The dependent variable is the percentage of targets reported.

Describe the CogLab attentional blink experiment’s expected data

The expected result is that the percentage of reports for the first letter do not vary much with separation. For the second letter, there should be few reports at separation zero, and the percentage of reports should increase with separation.

Describe the CogLab attentional blink experiment’s conclusions

Detecting the first letter causes you to miss the second letter

How is the attentional blink related to information processing and processing resources.

Suggests that processing the first target letter, “J” uses up resources that would otherwise be used to process second target letter, “K.” Attentional focus and refocus takes time (and for this task takes approximately 400 ms)

Describe the CogLab visual search experiment

On each trial, circles and squares of various colors were shown on the screen. Your task was to determine whether or not there was a green circle among the shapes.

For the first set of trials (feature search), the other distractor shapes were all blue. For the other set of trials (conjunctive search), some of the other shapes were blue circles and others were green squares.

The independent variables in this experiment were (1) the type of search (feature or conjunctive), the number of distractor shapes, and whether the target is present or absent. The dependent variable was the response time between the appearance of the stimuli and your response.

Describe the CogLab visual search experiment’s expected data

The expected result is that for both feature searches, the reaction time does not vary much as the number of distractors increases. For conjunctive searches both lines should increase with the number of distractors. The conjunctive-absent searches should increase twice as fast as the conjunctive-present searches.

Describe the CogLab visual search experiment’s conclusions

Feature search can identify target within either feature map (color or shape) with no searching required. Conjunctive search cannot identify target within either feature map alone (requires search by comparison across feature maps. Serial process takes time)

In the CogLab visual search experiment, what pattern of results indicates the use of attention?

Conjunctive search for target absent has a slope twice as steep as for target present because when the target is present you find it, on average, after searching half the items and then can stop the search. For target absent searches, you must search all items to verify each is not the target

In the CogLab visual search experiment, what varies as the number of distracters is increased?

As the number of distractors increases, so does the mean response time

What is automaticity?

The process whereby a task goes from requiring a lot of attention to requiring little is called automatization

What is the Stroop task?

Identify the color of ink for words

It takes longer when the words are color names (Word name interferes with ink color naming but ink color does not generally interfere with word naming)

What are the methods of the whole-report and partial-report experiments?

In the whole-report experiment, subjects are shown a matrix of 12 words and then asked to report how many letters they remember.

In the partial-report experiment, subjects are shown the same matrix of letters but are only asked to report a portion of them

What are the key differences between the partial-report and whole-report experiments?

In the whole-report experiments, subjects are asked to report all of the letters seen whereas in the partial-report experiments, subjects are only asked to report a line of the letters seen (4) randomly assigned after viewing the matrix

Why does the partial-report method indicates that more items are stored by some sensory memory than the whole-report method indicates?

In the whole-report experiments, subjects remember on average 4.5 of the letters (37.5%).

In the partial-report subjects on average remembered 3 of the 4 letters but because they didn’t know what row they were supposed to memorize until after the matrix disappeared, they had to memorize the whole matrix. This shows that they actually remembered around 75% of the matrix as opposed to the 37.5% that the whole-report experiment results suggested.

This shows that precept can be very fleeting

Explain the iconic memory experiment that can be used for both adults and infants

Blaser and Kaldy (2010) modified the partial-report experiment to test iconic memory of infants

Show colored shapes, take away two, and put another 2 back (1 is unchanged while the other is changed)

Infants show a preference to look at the changed object for small enough set sizes (Monitoring infant eye movement to see where infant is looking)

Results were good if there are two objects removed and the infants showed strong preference if 4 are removed and 1 are changed. Things started to get rough when you get to 8 objects removed and 1 changed

Infant iconic memory is actually quite similar to adults

If you ask adults to report the location of the changed color item, they do better than infants (who did not understand the ‘task’) but not by much. The adults experiences a sharp drop in performance as the set size increased to around 5.75 while for infants it was around 5.0

How do masking effects influence iconic and echoic memory?

With a mask, you do not have time to focus on

What is involved in an immediate serial recall experiment?

Immediate serial recall

After given a list of items we.g., digits, letters, words, subject must report them back 1) no delay (immediate, 2) in the correct order (serial), 3) no cues (recall, not recognition)

What are the different properties of iconic and echoic memory?

Echoic: longer duration (seconds), smaller capacity, significant for some memory tasks

Iconic: brief (less than a second), probably has little to do with “normal” memory

What is the hypothesized role of iconic and echoic memory on the serial position curves produced under immediate serial recall (modality effect)?

Echoic memory shows recency while visual shows primacy

What is the suffix effect?

The suffix effect is the selective impairment in recall of the final items of a spoken list when the list is followed by a nominally irrelevant speech item, or suffix.

How do the properties of echoic memory account for the suffix account?

Echoic memory has recency so you are more likely to remember the last thing you heard. Recency is lost though when something else is said that is not relevant making it hard to remember what was said.

How do phone operators avoid the problems of the suffix effect?

They give the phone number but do not say “goodbye” or “have a nice day'“ as you would forget the last part of the phone number if they finished with pleasantries dues to the suffix effect

Describe Ebbinghaus’ experiment

Measure how long it takes to learn a list of nonsense syllables perfectly

Relearn the list at later points in time (a different list each time)

Measure how long it takes to relearn the list

Calculate savings (Savings = the difference between the original and relearn time divided by the original time)

If savings =1, subjects do not need to relearn, perfect memory

If savings=0, subjects show no evidence of earlier learning

What were the results of Ebbinghaus’ experiment?

It took less time to relearn things after previously learning them. Savings was never 1 though because this would imply that subjects do not need to relearn (perfect memory)

How do Ebbinghaus’ results suggest the existence of a long-term memory (LTM) system?

Ebbinghaus’ results suggest that memories can last a very long time, in some form as it took less time to relearn things that had previously been learned

Memories were believed to be “stored” in a memory system and did not just fade away (otherwise, the curve should not asymptote above zero)

What are the properties of the LTM system?

High capacity (no limit)

Long duration (forever)

Describe the Peterson & Peterson/Brown-Peterson memory experiment

Give subjects trigram then ask them to count backwards by 3’s (for a varying duration) and then recall the trigram

What were the findings of the Brown-Peterson experiment?

The results of the Brown-Peterson study suggest that some aspects of forgetting are process driven (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

(Suggests some memories last only a few seconds. Even if you are distracted, you can recall the trigram if only a short time has passed. If many seconds have passed, while you are distracted, you cannot recall the trigram. This is because memory has “decayed”, or something like decay, while you were doing the distracting task)

How do the findings of the Brown-Peterson experiment suggest a short-term memory (STM) system with certain properties?

STM only lasts a few seconds

What was the procedure of Miller’s memory span study?

Tried to see how many items can you correctly recall immediately after exposure?

What were the results of Miller’s memory span study?

You can only remember 7 ± 2 items

How do the results of Miller’s memory span study suggest an STM system with certain properties?

Suggests that STM has a small capacity

Why do the properties of STM make it challenging to win a pizza?

The Little Caesar’s in W. Lafayette used to have a game where you could win a pizza To win, you must repeat a sequence of flashing lights (changes every time) but the sequence gets longer until you make a mistake. To win anything, you need a sequence length >7, which is nearly impossible with STM properties as STM has a small capacity (about 7 items) and a short duration (seconds)

Describe the modal model of memory

When something is memorized, items are first held in the STM as a temporary store but may transfer to LTM as a permanent store, but this transfer takes time.

How might the STM and LTM system offer an account of the u-shaped serial position curve that is seen in some memory experiments?

Primacy uses the LTM (explaining why people remember the first few things more) and recency uses the STM (explaining the peak in memory of the last items). Neither LTM nor STM have properties that would help with the middle

What are the three types of hypothetical searches of STM considered by Sternberg?

Parallel: Target item is compared to all the items in memory at the same time. The answer (yes or no) is returned after all items have been checked

Serial terminating: Target item is compared to each item one after the other. The answer (yes or no) is returned after the target is found or all items are searched

Serial exhaustive: Target item is compared to each item one after the other. The answer (yes or no) is returned after all items are searched (regardless of whether target is found or not)

Describe the predicted pattern of experimental results of the different search types considered by Sternberg

Parallel search: Reaction time is the same for a yes response and the number of items does not matter

Serial terminating search: reaction time is faster for a yes response because you have to go through items one-by-one until you find the target. RT increases with set size.

Serial exhaustive search: Reaction is the same for a yes response as a no response because you have to go through every item and then report answer. RT increases with set size.

Describe Sternberg’s experiment on the search of memory

On each trial, you saw 1, 3, or 5 numbers for 1.2, 3.6, or 6 seconds (respectively). Then, 1 to 3 seconds later, a single number was shown. Your task was to indicate as quickly and as accurately as possible whether this probe number was in the list just presented.

The independent variable is the number of digits in the memory set (1, 3, or 5). The dependent variable is the speed with which you made a correct decision.

What were the results of Sternberg’s experiment on the search of memory?

Sternberg found that the "Present" and "Absent" curves were nearly superimpose

What do the results of Sternberg’s experiment on the search of memory mean?

Memory is serial, (one item at a time) and checking each item takes approximately the same length of time (approximately 40 milliseconds)

Memory is is exhaustive (search always goes through all items)

Why it might make sense for search of memory to be serial exhaustive instead of serial self-terminating?

Exhaustive search makes sense if search of STM is done by some process that is

• very efficient (can search very quickly)

• dumb (doesn’t bother to stop itself)

• initiated by some other system (a controller)

  • eg search short term memory, search long term memory

Describe the procedure and general findings of the study by Brooks

Part 1: Spacial mental task (diagrams). Classify corners in a letter as a top or bottom corner (yes for top, no for bottom)

Part 2: Verbal mental task. Read the sentence and categorize the words as a noun or not

Results: Measure the time to finish the mental task for each response type (diagrams/pointing, sentence/pointing, diagrams/verbal, sentences/verbal)

When you have to respond by pointing, it is easier to work with sentence information than diagram information

When you have to respond verbally, it is easier to work with diagram information than sentence information

How are the existence of separate visuo-spatial sketchpad and phonological loop systems consistent with the results of Brooks’ study?

The results suggest that there are two relatively separate systems

One deals with visuo-spatial information and must do the pointing response and mental diagram task

One deals with verbal information and must do the spoken response and the sentence task

These system have only limited resources and capabilities Asking a system to do two things at once (e.g., pointing and mental diagram) slows down the system
Splitting responsibilities across the systems (e.g., spoken response and mental diagram) can be done quickly

What are the similarities between STM and working memory?

Working memory is an extension of STM

Both focus on current thought and awareness, have a small capacity, and rapid forgetting

What are the differences between STM and working memory?

The working memory is a processor of information, not a storage device the STM. It hypothesizes mechanisms that lead to new memory properties

What are the two subsystems of the phonological loop?

The articulatory control process and phonological store

What are the characteristics of the articulatory control process?

Converts non-speech information into speech code

Rehearsal/refresh

What are the characteristics of the phonological store?

Similar to how we first described STM (items decay from memory)

Refresh restarts the decay process

How is the loop capacity related to both the time needed for items to decay from the phonological store and the rate at which the articulatory control process can rehearse items?

Like spinning quarters. You have to keep refreshing/rehearsing (spinning) the quarters (memories) or they will fall flat (drop out of the loop) but as you add more things (spinning quarters), it becomes harder and harder to keep them all spinning before they run out of time (working memory can only hold so much at once)

A set of items that takes longer to rehearse should be harder to remember as it is more likely that some items will drop out before you get back to the first item

What aspect of the phonological loop seems to vary with development?

The rate of rehearsal

What is the word length effect?

Memory span is related to the length (number of syllables) of words. The shorter the words, the more you can remember

How does the working memory explain the word length effect?

Your working memory can only hold things so long so you need to be able to rehearse them all before in a certain period of time to restart the clock and avoid forgetting. The longer a word is, the longer it takes to rehearse so the harder it is to rehearse everything

Why is the rate of rehearsal important for the explanation of the word length effect?

Your working memory can only hold things so long so you need to be able to rehearse them all before in a certain period of time to restart the clock and avoid forgetting

How do the properties of working memory explain some aspects of digit span for different languages?

Some languages are spoken more quickly than others, which should allow for a larger memory span

How might the properties of working memory affect measured IQ scores?

Part of the IQ exam checks memory span. If you speak a language that is spoken more quickly, you have a larger memory span making this part of the test easier.

What must the subject do in a study of articulatory suppression?

Subject sees (hears) a list of phonemes Also repeats a phrase over and over (e.g., “tippy-toe, tippy-toe, tippy-toe) and then is asked to list the phonemes they heard

Why does articulatory suppression reduce memory performance? What happens to the articulatory control process?

The ACP is tied up. Without being able to rehearse, more forgetting occurs

What is the basic effect of phonological similarity on memory performance?

When things sound similar, it makes it harder to remember