Different Models of Attention

The topic of discussion continues to be attention in this paper,

Single-Mindedness:      

- We have the capacity to perform only one demanding task at a time.

It is believed that attention starts immediately after icon and ego

No higher level processing is performed at this time.

Some models suggest that attention must be a low level process

Early Selection Model

Blocks the information coming from the left ear as attention is paid to the right ear.

According to these models, attention happens early and it is a low level process.

Attention and Meaning

It can be inferred that if attention is a low level process than meaning should not have any relation with attention.

To see this, an experiment was designed by undergraduates at Oxford University.

- Shadow Meaningful Messages

The subjects were given the following messages in left and right ear respectively.

-          Left Ear: John Eleven books

-          Right Ear: Eight writes twenty

In this experiment, the subjects reported:

John writes books

This experiment illustrated how subjects switched between ears to get meaningful messages.

So, the findings of the experiment were as follows:

-          Attention can use meaning, a higher level process

-          Attention is probably not an early selector but a late selector

Triesman's Experiment

Triesman(1960) conducted the following experiment:

-          Asked the subjects to shadow a message in the left ear

The message shadowed in the left ear was:

Left Ear: I was going there when/China smoke lovely chirping

Right Ear: books, chairs, tables, elephant/ I saw a bright flash

The experiment revealed that many subjects switched between ears to follow the meaningful message.

That means that something is given meaning even before the attention is totally focused on that content.

This created a very important paradox in cognitive psychology.

It may be possible that attention is an early selector. Triesman did not said that attention is a high level process. He said that higher level processes in the brain may be playing a role on early on from the point of view of attention.

One experiment is telling that physical features like pitch, loudness ad which ear it is presented to are more important than meaning. Other experiments tell you that the meaning plays a central role in terms of how attention is focused. This created a very important paradox in cognitive psychology.

Suppose you go on a wedding dinner, and people are chatting in groups and you are paying attention in the group in which you are chatting. All of a sudden someone in the other part of the group said your name; all of a sudden your attention will shift from the group you were in to the group where your name was spoken.

This is an example of what Triesman was saying, that is an example of what Gray and Wiederberg was saying.

How is it that if we are using attention for selection

Information is coming from the left. The arrow represents different visual or auditory information.

The information falls on our senses. Senses take that information in their own limitation, majority of the information that goes to the short term storage.

We are not getting all the information that is falling on the senses.

There are many things which our eyes cannot possibly see.

e.g. ultraviolet or infrared

Our sensory memory has some limitations. Short term store seems to be almost limitless.

This short term store is known as sensory store. We will talk about short term memory ahead. It is not good to get confused with that.

Don not confuse short term store and sensory register with short term memory.

Short term store is where all the information acquired by the senses is retained but fir a very short time.

Selective filter is followed by Limited Capacity Channel.

It is because of the limited capacity channel that the filter is previous to it. If you put load on the filter, it will be worthless.

Limited capacity channel is sending 3 channels:

1.       Some information goes back to short term store. While you are listening to this lecture, somebody else is talking and somebody else is talking to somebody else.

With this feedback loop, attention is paid to the thing which we are already attending.

2.       Store of conditional probabilities of past events

Information is send to the store of conditional possibilities of past events to see what kind of conditional probability does it has.

If something is important to us, the attention automatically goes to t hat.

Cocktail party phenomena

Your name is said somewhere and your attention goes there.

Whenever your name was taken in the past, you were attending to that event. Because the sound came even though you were paying attention to something else. Because it was something you have heard in the past over and over again, it was automatic.

Your attention automatically shifts to the group where your name is taken.

Based in your past experience you switch your attention and there is a feedback loop to the selective filter.

One arrow from the Limited Capacity Channel goes to:

3.       System for varying output until some input is secured

It changes our behavior in the direction of attention.

If I am doing something very important and all my attention is to that task and something else happens in the environment to which to pay attention, I will orient my body to it. I will probably move closer  to that situation and I will make sure that I direct all my physical orientation to that situation.

Effectors on the top of the slide refers to the mascular response or the motor response that may be given

So, Broadbent model of attention is an early selection model in which there is a short-term storage and from that short term storage immediately attention selects some information for further processing. It is a filter model or it is also called a bottleneck model.

When you hear your name for that your response is varied.

From this phenomena it is decided what your effectors will do,

Selective filter is immediately after short term store.

Attenuator Image

Shadowed message has same pitch, loudness, etc.

In between that there is no filter but an attenuator.

Attenuator is one which weakens a signal and lets one remain strong.

Attention weakens information coming from one ear and the information coming from another ear goes without problem.

After Attenuator, there are thresholds of high and low.

Words like table, green are ordinary in your mental dictionary.

Words like your name or some subject you are interested in have a very high importance in your mental dictionary.

The subjective loudness like that of your brain escapes the weakening of your attenuator.

Attenuation means the weakening of something(signal), weakening a signal

The attenuator in the system tells us.

Norman Model

Norman's model is not very popular anymore.

He tried to say that attention is very later.

It is reverted because it is starting from above.

If you see it from up, you will see that sensory input is coming from up and It is processed without any filter of attenuator. Everything is processed.

To conclude, we have two competing models:

1. Early selection model

2. Late selection model

Early selection model has two types:

-          Filter model by Broadbent

-          Attenuator Model

Filter means it lets something go and makes something stay.

Attenuator is one that lets everything go but weakens some signals.

In this paper we will again talk about “attention” and also discuss some philosophical questions like the concept of psychological time.

When we talk of sensory memory, the high level processes are not involved in it.

Vision – Iconic Memory – Decays in less than a second

Hearing – Echoic Memory – decays in less than 5 seconds

Why is attention Important?

Let’s see why it is important to study attention and why attention is important.

- Attention is an area which is perfect example of cognitive psychology

- It highlights the various interests people have about cognitive psychology

 - “Attention” is a subjects which combines the philosophers and scientists again as philosophers and scientific experimenters unite again to unravel attention.

- Philosophers theorize and scientists experiment to reach the same goal

With their experiments, scientists check the theories which philosophers present.

Cognitive Science and Computer Science

*- Cognitive psychologists work with computer scientists for making simulations, although this is not their primary job.

Computer scientists can help the cognitive experimenters with simulation. For example, a simulation of an eye would be a camera attached to a computer

Attention

Let’s again switch our attention to the topic of attention.

Attention selects some information from the perceived stimuli for further processing.

However, attention is able to select a very small amount if visual information that we have.

Attention selects some information from the perceived stimuli for further processing.

It is to be noted that attention plays a crucial role in the stage of selection of information after it is in sensory store before decay.

Attention from the viewpoint of a Philosopher

Here we will discuss the philosophical view to understand attention .

There are various metaphors used to understand attention. Some compare attention to a spotlight, some to a filter, some to a bottleneck.

Let’s see them one by one.

- Is it a spotlight? e.g. a beam? (On Stage)

When someone is standing on the stage, we darken the rest of the stage and throw a spotlight on t he speaker.

Let’s assume from a philosophical point of view that attention is a spot light. Spotlight has a capacity, stage, area.

Attention by its very nature, if we accept the spot light metaphor, is very limited thing and can only focus on one thing.

Is it a filter? E.g. a sieve(dirt is thrown out, flour remains)

Some people compare attention to a filter. Just like a sieve. In a sieve the dirt is thrown out and the flour remains. So attention is compared to a sieve used for filtering.

Is it a bottleneck? e.g. A narrow lane?

Some people compare attention to a bottleneck or a narrow lane. If we move from a 3-way lane to 1-way lane, there is some narrowing that constitutes attention.

As we see in the bottleneck example, various sensory inputs go in the bottle and the attended information is filtered,

 Is it a limited resource?

Some people compare attention to a limited resource like petrol, manpower, etc. Thus, attention can also be viewed as a limited resource and there is limit on how it is spend.

Let’s examine the limited resource analogy of attention.

We can say that workplace is a limited resource.  If we want to employ 100 employees and a very small room to start the company with, then we cannot employ 100 employees. Then we have to narrow down to 3-4 employees. This narrowing down is an example of attention.

All the questions above are philosophical. It again shows that cognitive psychology very much touches philosophy.

From all the above examples we learn that there is a sense of single-mindedness in attention.

An objection was made to “single-mindedness” arguing that what about when we were walking and talking at the same time.

This made cognitive psychologists change the idea a little. The idea was narrowed down to:

We have capacity to perform only one demanding task at a time.

We cannot perform two demanding tasks simultaneously.

Also, we quickly lose information if we don’t attend to it for a limited amount of time.

Limitations in sensory tasks

-         

      Attention appears to be the real  reason for the whole report performance( limited recall)

-          Limitations of icon and echo are actually limitations of attention

-          Sensory information needs to be stored in a form that can be retained.

-          Selection of this transformation happens only to attended items.

-          More information is lost because attention has limited capacity

Dichotic Listening Tasks:

- Cherry(1953); Moray(1959)

Dichotic Listening:

Through the headphone, one ear is presented with one message, the other ear with another message.

Subjects pay attention to (shadow) one message only.

Let’s look at the shadowing paradigm now.

Shadowing Paradigm:

Let’s see this all information is given to the left and right ear

Left ear: ran, house, Ox, Cat

Right Ear: Tea, Job, books, look

And the subject is told to attend to the left ear.

These experiments led to several models as shown below.

Early Selection Model

Information is selected early, soon after sensory store; the higher level processing is not done.

The meaning of the words does not have an impact at this stage in this model.

Thus, attention must be a low level process. Attention must be a low level process because it comes into play just after we have received the information through our senses.

Information is coming from both the ears. There is a nexus of both the ears which comes a lot before reaching the brain.

The information that goes through auditory nerves. First of all, there is a sensory register like the icon or the echo. First the information comes to it. After that there is a filter.

This filter is attention. After that there is pattern recognition.

                                            

Attention and Meaning

- Undergraduates at Oxford

- Gray and Wedderburn(1960)

- Shadow meaningful messages

- Left Ear: John Eleven books

- Right Ear: Eight writes twenty

The subjects reported: John writes books.

Thus attention has to do with meaning.

References:


http://www.youtube.com/watch?v=cU7eJHnvkNc&feature=related

“Hardware” relating to Cognitive Psychology

 “Hardware” relating to Cognitive Psychology

- Nervous System

While discussing the nervous system, it is important to discuss the hardware or the nervous system.

Let’s talk about the sense organs we use to receive information i.e. the eyes and the ears

Structure of eyes and the ears imposes limits on our sensory system because there is a limit to what the eyes can see and the ears can hear. There is some range which the eyes cannot see and there Is some range for which the ears cannot hear. Rather, we can say the other way around. The eyes can see only limited and the ears can hear only limited.

In considering the computer-brain analogy, the eye and the camera are analogous.

When we consider computer-brain analogy, we primarily concern ourselves with the eyes and the ears because sound and camera are very much used in computer and are easy to simulate. Taste, smell are not used by computers as yet.

How we process sound?

The information goes to the visual cortex where the information is processed.

*- Delay detectors indicate from where the noise is coming.

It is important to note that the sensory system imposes a limit to our information processing ability.

How sensory information is processed in initial stages?

Information processing (of visual information) is done in the visual cortex.

Let’s look at some classic experiments to see how the information is processed.

Stephen William Kuffler (1913-1980)

Information Processing in Visual cells

How does sensation transform into perception?

*- Kuffler studies ganglion cells and discovered on-off and off-on cells.

Ganglion cells are before brain cells and after optic nerve.

There are two kinds of visual processing:

-On-off cells

-Off-on cells

If the light fell on the center of retina, on-off cells were activated,

 If the light fell in the periphery, off-on cells started firing.

Neurons don’t use pistols

Neurons don’t use a pistol to fire. When we say neuron firing, we mean that the neurons release electric impulses to communicate.

By they are activated we mean that neurons start firing electric impulses.

Ganglion Cells

When light falls on the center of retina, the on-off cell fires a lot but the off-on cell did not fire at all.

                                          Source: Virtual University, www.youtube.com

In the diagram above:

On the left side, there are on-off cells

On the right side, there are off-on cells.

The lines indicate the time

If lots of lines are together they indicate that the neuron is firing many times in one second.

If there is less number of lines means it is firing less.

1. Central light spot

When light was on the center of the retina, the on-off cell fired a lot but the off-on cell did not fire at all.

2. Peripheral light spot

The off-on cell show an opposite reaction as shown by the on-off cell

On-off cell did not fire, there are no lines there

The off-on cell has lot of lines, the off-on cells are activated when there is light in the periphery

3. Central Illumination

If some place is lit, and the illumination is on the center then there is lot of firing in the on-off cell.

4. Surround Illumination

On-off cells are silent

5. Diffused illumination

Both cells are activating but firing very slowly.

The location is determined through on-off cells and off-on cells.

Hubel and Wiesel

- Hubel and Wiesel (1962) constructed a very important experiment in cognitive psychology.

They started their experiment with cats and used their visual cortex.

- Hubel and Wiesel found out that the visual cortex is more complex than on-off cell and off-on cell.

- They discovered:

*- Bar detectors and edge detectors.

*- Edge detectors help us to understand where an object ends and the other starts.

Cats also have the same edge cells which were discovered by Hubel and Wiesel.

David Marr's Work

*- Marr and Hildreth (1980) combined the output of off-on detectors to calculate bars and edges of various widths and orientations.

*- Symbolic descriptions were created.

Computer scientist and AI experts make computer models.

- Marr simulated on-off cells and off-on cells in a computer

- The information was gathered through a program and symbolic descriptions were created.

- Boundaries of objects in the real images present a difficult problem in computer vision.

The computer program was used simulating edge detectors and bar detectors.

This is done because computer vision is an important part of our technology

For example: an airplane running on autopilot

Edge detectors and bar detectors use camera to find out whether there is a bird or cloud or another airplane ahead.

Clouds

For a computer, detecting the image above is a nightmare scenario.

Software Level

What happens when we get all this sensory information?

Sensory Memory

- What happens with the sensory information we receive? All information is held somewhere.

- Cognitive science deals with only 5 senses which are observable and measureable.

-Vision

-Hearing

-Smell

-Taste

-Touch

Most of the work has been focused on vision and hearing because we are limited by technology to conduct experiments on smell, taste and touch.

- Any experimentation that we do in the area of cognitive psychology, we feel that only a limited technology is available to us.

What is Sensory memory?

Sensory memory allows us to take a ‘snapshot’ of our environment and to store this information for a short period. Only information that is transferred to another level of memory will be preserved no more than for two seconds.

Sensory memory holds a short impression of sensory information even when the sensory system does not send any information anymore.

-We keep getting the same sensory information if we are in the same background.

-The sensory memory holds the information for a very brief period of time and that brief period is usually no more than a second.

How we know this?

Visual system experiments on human beings

In the case of cat, electrodes were entered in the brain of the cat and the electric impulses were measured.

*- In human experimentation, the subject is made to sit and is asked to look at a screen, a computer screen normally. A dot is shown on the screen with blank white screen (dot is located in the center) and the subject is asked to focus on the dot.

- Instead of a dot, a set of letters is presented at that fixated point, where the subject is focusing.

- After a very brief period letters (stimuli) are removed.

Sperling's partial report procedure

The same array was presented to the subjects but the subjects were asked to report the letters according to the cue.

(A beep in this case, an auditory cue)

After the array was turned off, a tone was sounded

- High

- Medium

-  Low

High tone cue for reporting the top row.

Medium tone cue for reporting the middle row.

Low tone cue for reporting the bottom row.

It is to be noted that using this method:

*- Subjects reported at least 3 out of 4 letters.

*- Because the subjects did not know beforehand which row will be cued, they had to have 3 letters from each row available to them.

The decay in Visual Memory

The number of letters available for the partial-report condition decreases with delay for the cue tone.

All the information that we are getting from our memory is being stored but for a very brief period of time.

References:

http://www.youtube.com/watch?v=zuqGO_r6s5Y&feature=related

Cognitive Neuropsychology

Cognitive Neuropsychology

It is something more than just studying the nervous system.

In computer-brain analogy, hardware is analogous to the nervous system.

We need to study cognitive neuropsychology because description of cognition at the hardware level lays the foundation of understanding cognition at software level.

A lot of visual processing and a lot of auditory processing takes place at hardware level as well.

Higher level cognitions will remain a mystery as far as the hardware level is concerned and we need a software level description.

There is difficulty studying neuropsychology because we cannot open the brain and see what is inside it.

Neuropsychological Methods

The traditional way to look at the neuropsychology was to actually look at the structures involved in the nervous system.

Structures involved in the nervous system are the spinal cord and the brain.

Spinal cord is usually responsible for the basic motor processes that reflects like transmission or sensation but nothing very deep or complicated.

Reflex action is controlled by spinal cord.

Brain is not mind

Brain is not the same thing as mind. Mind is an abstract concept which does not exist physically.

Mind is a software level concept. It is a concept which cannot be realized “physically”. It does not physically exist.

The skull protects the brain.

How to study the brain?

Neuropsychological methods include studying people who had different types of brain injuries.

Brain has two hemispheres:

Right Hemisphere:

(Controls the left side of the body)

Left Hemisphere:

(controls the right side of the body)

Corpus callosum – connects right and left hemisphere

If is the corpus callosum is damaged then two hemispheres cannot communicate.

This results in strange behaviour.

Spatial processes – Vision, artistic ability, creative tendency, ability to understand visual images is determined by the right brain..

Language , verbal skills are determined and controlled by the left hemisphere.

Visual perception is done in the right hemisphere and the language is controlled by the left hemisphere.

Left brain function:

- Number skills

- written language

-Reasoning

- Spoken Language

- Scientific skills

- Right hand control

Right Brain function:

            -  3-D forms

            - Insights

            - Art awareness

            - Imagination

            - Music Awareness

            - Left hand control

Visual perception is done on the right hemisphere and language is controlled by the left hemisphere.

A common technique is to study the brains of dead people

We can study the brains of dead people but the shortcoming is that we cannot understand living behaviour.

Neuroimaging

-          What is an X-Ray?

-          We use x-ray a lot when people have accidents

By doing x-ray of the brain we can get some information.

It is not a very good method though.

x-rays can be used to study the brain but it is not very useful method in cognitive psychology.

MRI Scan

Magnetic Resonance Imaging, or MRI is a painless and safe diagnostic procedure that uses a powerful magnet and radio waves to produce detailed images of the body’s organ and structures, without use of x-rays radiation.

Neuropsychological Methods

Animal studies are very important in neuropsychological methods.

There is a lot of evidence that man is similar in many ways to animals.

Animals can be studies to understand the functioning of the brain.

Animals do not possess language so we cannot use animals to understand the language.

Anima; studies are still important ways to understand the hardware.

Ethical Issues:

There are serious ethical issues in studying animals for cognitive neuropsychology because lethal and cruel practices are performed on animals.

Some radioactive or other dangerous chemicals may be injected in the body or brain of the animals. Animal rights activists have a lot of concern related to these issues.

Nervous System

Components of Brain:

1-      Cerebrum

2-      Cerebellum

3-      Medulla Oblongata

Cerebellum is responsible for learning behaviour or classical conditioning type . Evidence of classical conditioning is in cerebellum.

If we see the cerebellum after conditioning and before conditioning, there are some changes in how it is working.

Classical conditioning type is in cerebellum.

Most higher level processes originate in cerebrum. If there is software level type of activity, it happens in cerebrum.

Different parts of the brain

At the top we have the forebrain which contains:

-          Cerebrum

-          Thalamus

-          Hypothalamus

Towards centre, we have structure called the midbrain.

Below is the hindbrain. Hindbrain has:

-          Pons

-          Medulla Oblongata

-          Cerebellum

Cerebral cortex – all interesting activity takes place. Related to attention, imagery and language.

If you are planning what all you will do tomorrow the most active area of your brain will be ‘cerebral cortex’.

If you do a little experiment that you are explained the way to home to someone the you will notice some changes. What changes those will be one cannot predict. Then cerebrum will have some activity going on.

Structure of neuron

source: morphonix.com


When we talk of cerebellum, we talk of firing of neurons.

Our whole body is made of cells. All living beings are made up of cells. Neurons are specialized cells which are found in the nervous system.

There are so many neurons that we may never be able to know what exactly happens when we are thinking one thought and then we are thinking another thought. So, every image, every thought cannot undergo neuronal one-to-one mapping.

We can see some processes happening through which neurons transmit and transfer information.

We can see some processes happening through which neurons transmit and transfer information.

Dendrite receives information.

Nucleus is the center and the control system of every cell.

Axon – takes the information processes in a neuron

How do neurons exchange/transmit information with each other?

The axon is connected with the dendrite of the other neuron through a Synapse. They do not touch each other physically.

A synapse means a connection usually neurons do not directly touch each other. The axon of one connects to the dendrite of other. They do not connect by physical touching and there is a slight gap between them.

They are intertwined but at a distance. b/w them is a fluid/

The fluid helps in transmission. It is known as a neurotransmitter.

Due to chemical changes in neurotransmitters, the axon transmits information to the dendrite.

References:

http://www.youtube.com/watch?v=CQHt24VKeAs&feature=channel