Psychology, Notes 3 -- Attention
A. Where we are/Themes.
E. Automatic processing.
II. Where we are/Themes.
A. Here are some situations:
1. You're driving in a strange neighborhood looking for "Long"
street. You accidentally turn on "Lone."
2. You're thinking about a quiz that's coming up in your next
class as you walk there. Someone calls your name, but you don't
3. You arrive late at a party and try to find your friends.
4. You're driving home and want to stop at the store.
you find yourself at home and you didn't stop.
5. You're trying to think about the research paper you're working
on, but you keep thinking of the great first date you had last night.
What do these have in common? Attention. The topic for
this unit is to try to explain each of these facets of attention.
It plays a role in detection (the first situation), filtering and
(the second), search (the third), automatic processing (the fourth),
concentration (the fifth). We'll have something to say about each
of these as we go.
B. Where we are. Remember, we're working our way through
this box model of the mind. We've talked about the sensory
and pattern recognition (last time). The register holds
briefly, and pattern recognition figures out what the information
Today we're looking at the "filter" and "selection" components.
of these are controlled by attention. Attention allows you to
out some information, and select from what's left. Overall,
helps pass information from box to box and provides the mental energy
each box's tasks.
Attention: (1) highlights parts of the environment and
other parts, (2) primes a person for speedy reaction, and (3) helps you
retain information. The basic processes are focalization
and concentration (staying on a subject).
1. Is attention's effect early or late? In other words,
do you process to a high level (like after pattern recognition) and
select, or do you select early? The model we're working from is
a bit. It puts the filter early and selection late. There
some debate about where each of these goes (maybe they're the same
Putting some at both places is probably a safe compromise.
2. What is attention? It's treated as a magical property
that can transfer information around, choose information to attend to,
improve memory for information, block unwanted information, and prime
information. But, what is it? You're eventually going to
it equated with mental energy. You have a certain amount, if
using it to do some task, there's not much left over for other things.
3. What does attention do? We'll see lots of proposals,
some practical, some theoretical. Hopefully, at the end of the
we'll be able to make a chart outlining the role of attention in
A. Is there a threshold: Fechner. A threshold is
the minimum amount of stimulation required for you to have a
Some sample thresholds:
1. Vision: On a mountain in utter darkness on a clear night
you can see a candle 30 miles away.
2. Hearing: A watch ticking 20 feet away.
3. Smell: A drop of perfume in a three room apartment.
4. Touch: The wing of a bee on your cheek.
5. Taste: One teaspoon of sugar in two gallons of water.
It would be nice if a threshold would work like a step function.
Before you reach it, you get nothing. After you reach it, you
see something. Why? Since the threshold is the minimum, and
that should be based on physical features (like the limits on vision),
it should be a constant.
Unfortunately, the threshold looks more like an ogive. In the
middle, you sometimes see something, sometimes not. This makes a
threshold a statistical concept (point of 50% detection).
What's the problem? Partly attention. What you're looking
for can have an impact as early in processing as your ability to even
that something is there. Here's an example: You're getting
ready for a date. You expect a phone call to make final
When you get in the shower, it's pretty noisy, and some of the sounds
have similar frequencies as a telephone ringing. So, in this
listening for the phone could make you think you're hearing it ringing
when it isn't. You're a lot more likely to dash out of the shower
by mistake when you're listening for the phone to ring than when you
B. Signal detection: Swets, Green. Get rid of
talk about detection. We're going to separate the two features of
this situation: sensitivity and bias. Sensitivity is the limit of
your perceptual system. Some differences are easy to detect, and
some are quite difficult. Bias is your willingness to say you
The situation when you're trying to detect something always presents
you with the four options in this box:
The two states of the world (stimulus present, stimulus absent)
with two possible responses (see something, see nothing) yield four
Hit (H) = something, you see it. False alarm (FA) = nothing, you
see something. Miss (M) = something, you see nothing.
rejection (CR) = nothing, you see nothing.
Sensitivity has to do with the strength of the signal (thing in the
environment). Signals are always perceived against a background
environmental and/or neural noise. The stronger the signal is
to the noise, the easier it is to discriminate something from nothing,
and the higher the sensitivity will be.
Bias has to do with the perceiver's willingness to say that they see
something. They have to place a criterion somewhere along the
of evidence for a signal. Above the criterion, say "I see
Below the criterion, say "I don't see it." In a noisy
sensitivity is low, so you always have to make some mistakes (M or
Placing the criterion in different locations changes the likelihood of
these errors. If misses are expensive relative to FAs, make the
of evidence required for a "yes" very low. If FAs are expensive,
make it harder to say "yes." I can manipulate your bias by
the costs of these two mistakes. The whole situation can be
Why is this good? I can manipulate these and see what effect
your bias has on what looks like attention. The automatic part
is separate from the attention part (bias).
CogLab: We'll discuss your data from a signal detection
How does this relate to driving in a strange neighborhood? You're
looking hard for "Long" so your bias is low (it won't take much
for you to detect "Long"). When you see "Lone," there's a lot of
evidence for "Long," it exceeds the criterion, and you mistakenly turn.
Application: This section
has a lot of application to human factors. When detection is
crucial and you can't increase d', you have to set the criterion based
on the situation. I have some examples of medical images that can
make this more clear.
IV. Filtering. At some point, you have to choose
what to attend to. A filter is the place where the choice is
Before the filter, everything comes in. Only attended stuff comes
out of the filter. (If we decide a filter is even necessary.)
A. Early filter models. Broadbent places the filter early:
This is based on two sorts of evidence. The basic task is called
dichotic listening. You put on headphones and a message comes in
each ear. The messages are different. The first evidence
a filter comes from a task called shadowing. You listen to two
and repeat out loud (shadow) the one that is your target message.
What we look for is how much of the unattended message gets
If you have an early filter, little (or nothing) should get
Some examples of this: I have four samples. In one, there's
a change in speaker on the unattended ear. In another, there's a
change in language on the unattended ear. In the third, the
in the unattended ear switches to being played backwards. In the
fourth, nothing funny happens (this is called a "catch" trial, because
if bias is making you cheat, we'll catch you). Broadbent says "if
it was being processed, people would notice this, but they don't, so
Another sort of evidence for filtering also comes from dichotic
(Broadbent, 1954). I play numbers in both ears. Here they
for the first sample:
Then, I ask you to tell me the numbers. What happens is most
people report all of one ear, then all of the other
It's like a filter allows in one set of information, flips to the other
channel (ear) and lets the rest in. Test?
If I ask you to report them in sequential order (3,7,2,4,5,1) it's
really hard. Why? You have to flip the filter back and
If I speed up the transmission rate, it gets even worse.
B. Attenuation models. Problems: Some stuff can get
through. Cherry (1953) describes the cocktail party
You're at a party in a conversation, and hear your name from across the
room. Even though you're shadowing your conversation, your name
Treisman (1960) did a more empirical version of this. She played
two stories, one in each ear. At some point, the stories switched
ears. People who were shadowing briefly followed the story to a
ear even though shadowing was supposed to be to an ear, not a story.
What's the explanation? Treisman goes for attenuation.
It's kind of like turning down the volume on the radio. What
attending has a high volume, the rest has a low volume. The stuff
in memory has some threshold. If the volume exceeds the
you'll be aware of it, regardless of what you're attending to.
since the volume is louder on the attended channel, there's a better
of it getting through. For unattended stuff to get in it has to
pretty special (like your name) or very relevant (like the next word in
a story you're repeating).
So, it's not really a filter, just less in terms of amount.
C. Capacity models. A different way to look at filtering
is to think in terms of capacity. You have x attention to spend,
spread it around to all of the tasks that need some. The more
one task takes, the less there will be for other tasks. This is
an extended version of the attenuation model.
The basic paradigm for testing this is called dual-task. You
give a person two tasks and look at the way they allocate
Usually, one task is called the primary task, and the person is
to do as well as they can on this task. The other task is called
a secondary task. The person is supposed to do this too, but
on the primary task. If capacity models are a good way to think
attention, then the harder the primary task gets, the worse people
do on the secondary task. (The more attention you devote to the
task, the less you have to give to the secondary task.)
It's not really wise to talk about filters when you take this
Instead, the person processing information can select whenever they
but the more attention they have to devote to each item, the harder
will be. Example: It's easy to make a feature
(a blue 'S' surrounded by red 'X's and green 'T's). No attention
is required for an early filter that picks out blue things before
happens. But, if you have to decide based on meaning, that takes
attention (the energy that allows recognition to happen). A task
that requires more processing before you can select will take more
for each item, and will be really hard. Let's put all of that to
the test with an experiment.
Johnston and Heinz (1978): The primary task is shadowing.
Two lists of words are read, one in each ear. The easy version of
this is to shadow a female voice when a male voice is in the other
You can choose what to shadow before recognition, and it won't take
attention. The hard primary task is to shadow fruit names when
other ear has animal names. To know which you're shadowing, you
to process up to the meaning. That takes a lot of attention.
The secondary task is to respond to a light. You don't know when
it's coming, but when a light comes on, you push a button. The
of attention you have available to devote to the secondary task depends
on how hard the primary task is. With male and female voices you
have lots left over. With categories, you don't have much.
|Shadow one list (control)
Easy primary task (voices)
Hard primary task (categories)
So, making the primary task harder takes more capacity and reduces
performance on both tasks. Still, people can move the filter from
early (voice) to late (category) if they have to.
To tie it in with our example at the beginning, you don't hear someone
calling for you because you're devoting your capacity to thinking about
the quiz. The filter cuts out new inputs. Note how this is
an internal thing that's taking attention. What you think about
always have to come from outside.
V. Search. Look for one item in a set of unrelated
items. Treisman (1988) presents a model of this. She sees
kinds of search. Feature search is looking for a unique
This doesn't require attention. Conjunction search involves
features. This does require attention. Note how this
to capacity models. Feature searches are before pattern
and are easy. Conjunction searches require higher processing and
Example of conjunction and feature search (stimuli as in Treisman &
Conjunction search: You have to look for a combination of
(in this case, green and "T"). (Find the green "T")
T X X X
T T T X
X T X
T X T
T X X T
X X T
X T X
T X T
Feature search: You can look for a single feature (blue or
(Find the blue "S")
|| Just as easy:
T X X X
T T T X
X T X
T X S
T X X T
X X T
X T X
T X T
A target with a unique feature will "call attention" to its location
What do we know about these search tasks?
|1. Take attention (the more distracters there are, the
it takes to search)
2. Helped by cueing the location of target (know where
in maps to conjoin).
3. If you don't know the location, you can't tell what it is.
|1. Don't need attention, "pop-out" (no increase in time
2. No help from cueing (don't need it).
3. Know what without knowing where.
Why does it work like this? Attention. If you need
it's going to be hard. So, back to our party, if your friend is
only one with dark hair in a room full of blond people, he/she will be
easy to find. But, if you have to conjoin features (short, dark
male), that will be harder.
Detection. This is related to search, but it also has a more
real-world application. One thing for us to consider as we look
at your data is whether certain things might be more likely to be
detected than others.
VI. Automatic processing. Some tasks don't seem
to require attention. These tasks are ones that have been
many times, and appear to happen on their own when the appropriate
A. How do we know a process is automatic? Three criteria:
1. Occurs without intention.
2. No conscious awareness/Can't be introspected.
3. Doesn't interfere with other activities.
One way is to test this is to ask a person to perform two processes
simultaneously. If doing two things at once is no harder than
one thing, one of the tasks must be automatic. For example, if
can talk to me and do mental addition, talking or mental addition must
B. Example: Logan. Algorithmic processing is step-by
step, requires attention. For example, do alphabet
A = 1, B = 2, ... At first, problems like A + M = ? are
But, with practice, they get fast. Logan says it's because you've
stored the answer after practice, so it's retrieval instead of an
C. Classic automatic process: Reading. Two examples.
1. Reading by the whole word method. You don't do well
at counting letters because you normally don't process letters when
As an example, count the 'F's in the passage. Most people miss
"of"s, so they say two instead of six.
2. Stroop interference. It's hard to say "green" to "RED"
written in green ink when you're supposed to say what color the ink
Automatic reading (or word identification) causes trouble. Try
list (naming the color of the ink):
CogLab: We did a Stroop task as a demonstration of
methodology, but we can look at the data again here.
So, why do you go home instead of stopping at the store? Driving
home is automatic and happened without attention.
VII. Concentration. The last topic has to do with
your ability to pay attention. There are two sides to this
First, sometimes you have to attend to the same task for an extended
of time. For example, you might be writing a paper. This
be hard. Other times, an unwanted thought keeps intruding.
You don't want to pay attention to it. This can also be hard.
We can bring this into the lab with a suppression and expression task
(Wegner, Schneider, Carter, & White, 1987).
Suppression: Try not to think of a white bear. This can
be really hard.
Expression: Try to think of a white bear.
I have each group ring a bell every time they think of it, they go
five minutes. That's the suppression and expression curves.
Note that both groups start out thinking about it a lot, and then both
After suppression or expression, I reverse the task. So, if you
were suppressing, now you express. These people are almost
in their thinking about it. If you were expressing, it's about
same when you switch to suppressing as suppressing alone.
So, why can't you stop thinking about that date? It's like not
thinking of a white bear. Thought suppression is hard.
keeping on a task is also hard. We'll see some applications of
when we look at human factors psychology later.
Cognitive Psychology Notes 3
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