Attention and consciousness - summary of chapter 3 of Cognitive Psychology by Gilhooly, K & Lyddy, F, M

Cognitive Psychology
Chapter 3
Attention and consciousness

Attention and consciousness have the idea of selection in common.
We attend to particular aspects of information hitting our senses and seem consciously aware of only a limited view of the world at any one time.

Attention

Attention is a limited resource that is deployed to facilitate the processing of critical information.

External attention: selecting and controlling incoming sensory information (like features, objects, spatial locations, sensory modality and time points).
Internal attention: selecting control strategies and maintaining internally generated information. It involves regulating our internal mental life so we can achieve our goals (like task rules, responses, long-term memory and working memory).

The attention system: can be seen as independent from processing systems and it utilizes a network of anatomical areas that carry out functions that are specified in cognitive terms.
Three basic components:

• Alerting
• Orienting (type of external attention)
• Executive function (type of internal attention)

• The alerting system is comprised of brain areas in the brainstem and frontal cortex that are responsible for achieving a state of arousal.
• The orienting system includes brain areas in frontal and partial cortex that direct our processing resources to incoming information and includes areas such as the frontal eye fields that are involved with rapid strategic control of attention.

This orienting system is external attention since it has the function of orienting our sensory processing to incoming information.
The frontal eye fields are found in the frontal cortex and are involved with the generation and control of eye movements.

• The executive system includes the anterior cingulate cortex, regions along the medial frontal cortex, parietal cortex and additional regions in frontal cortex.
  The executive system is related to internal attention since it is critical for control of starting tasks and sustained maintenance of performing a task.

The altering system is a kind of ‘on’ switch that organizes our behavior for when a event might occur.
The orienting and executive systems on the other hand are important for organizing our behavior in response to what is happening in the world and what we should be doing.

Early theories of attention

The cocktail party problem: describes how we successfully focus on one speaker in a background of noise and other conversations.
But, our ability to tune into one speaker can be broken by certain sounds.

Filter theory

A filter is used to block irrelevant information so that only the important message would reach a central channel for further processing.
To goal is to get the important information on a piece of wire (information attention should select to put out the wire) so it can be transmitted to a receiver (our unconscious awareness).
Prior to accessing the central channel was a buffer that contained unprocessed information only one signal was let through the filter and all the other information in the buffer was flushed away.

Early selection: when the filter for attention occurs early in the stream of information processing.
The aspect of the model that only one signal was let through and all the other information discarded.

Late selection: when the filter for attention occurs late in the stream of information processing. This the filter eliminates some information that already been processed.
More extensive processing was performed leading to all stimuli being identified, but only the attend ones were given access to further processing.

Treisman
Replaced the total filtering of irrelevant information with one the intensity of the irrelevant information was diminished but not totally eliminated.
In this was, the diminished information might still get detected if it was of high priority to an individual.

Load theory.
The amount of processing an unattended stimulus will receive depends upon how difficult it is to process the attended target. If the principal target is easy to process than attention resources will overflow to irrelevant factors and these will be identified, indicative of late selection.
If the principal target is difficult to process then the irrelevant factors will not appear processed, indicative of early selection.

There is effectively only one channel of output to further processing and thus attention forms a bottleneck for information processing.
The filter theory is also known as the bottleneck theory.

Resource theory

Also held that attention is limited. But instead of the limit being the information capacity of a single central channel, attention was treated as a limited resource to distribute appropriately.
Metaphor: brain as a computer where various resources are available within the computing system and attention acts to get the right information to the central processing unit.
More aspects, like arousal and how different tasks influence attention.

A spotlight to describe how the resources of visual attention are distributed over space.
Just like a spotlight we can be shone on the location of a scene we want to observe, the resources of attention can be shone on specific visual locations of interest.
This spotlight of attention is able to move around the visual scene even when the eyes do not move. - Movement of the eyes towards a subject signal an overt shift of attention

• Moving attention when keeping the eyes fixed and attention moves is a covert shift of attention.

Zoom lens model
The intuiting is that just as a zoom lens on a camera will change how much of the scene is contained in the image, we could effectively have a zoom function for attention that zooms in and out to cover different amounts of the scene.
The amount of attention at any one location in the spotlight will decrease as we zoom out and attention must cover a larger area.

Attention can be characterized as being applied to objects, rather than simply the spatial location the the object occupies.
Only object features that are relevant for the task to be performed are processed.

Dual-task paradigm: arises when one measures performance on two tasks independently and together. If performance when performed independently and together is equal, then the two tasks do not compete for resources.
Results are consistent with the notion that attention is a limited resource that is shared between tasks.
When tasks are performed simultaneously, resources are split between the tasks and performance goes down due to decreased resources available for the individual tasks.
When resources are strategically diverted to one task, performance goes down in the order.

Some task combinations systematically appear to cause less interference between each other.
When tasks are more dissimilar to each other there is less of a reduction in performance when performed together.
The idea of a single central attention resource is not fully adequate to explain human performance.
With multiple resources one assumes that there are independent pools of resources, each of which is limited. A task will compete with some tasks for the same resources but with other tasks there will be no competition.
Our ability to do multiple tasks will depend on how far apart they are on the relevant dimensions. Being close along any one dimension implies competition for resources and a necessary reduction in performance.

Attentional mechanisms in perception and memory

A neural mechanism of attention in primary visual cortex

The feed-forward sweep: describes how incoming sensory information travels across the brain. A bottom-up process.
The primary visual cortex responds 40 milliseconds after a stimulus onset. By 80 milliseconds most secondary visual areas are activated. By 120 milliseconds activation can be found throughout the cortex.
Once an area is activated, it can interact with both higher and lower brain areas in a mode of recurrent processing (within a network, involves computations that occur in a cyclic fashion).
Neural tuning properties to visual stimuli are quite sophisticated even at short times after stimulus onset.
Neural mechanisms of attention could be effective in the very fist stages of encoding a visual stimulus.
Receptive field of a neuron indicates the physical space that simulates the neuron. In vision it is the region of visual field to which that neuron is sensitive if stimulated with light.

The normalization model of attention.
Two functions of attention:

• The capacity to increase sensitivity to faint stimuli presented alone
• The capacity to reduce the impact of task irrelevant distractors when multiple stimuli are presented.

A computational model of early stages of image processing in the visual cortex.
The input (or Stimulus drive) is multiplied by an attention field an divided by a suppressive drive to obtain the effect of attention on perception.
The suppressive drive includes the interaction of all the attended and non-attended elements of the visual input.
The stimulus drive and subsequent stages are a neural image. In which the brightness at every spot of an image corresponds to the response of one neuron.
The stimulus drive is the neural image of tho orientation in the image is represented if there were no effects of attention.
In the attention field, attention is applied.
The result of multiplying the attention field by the stimulus drive gives the suppressive drive that is more broadly tuned than the original stimulus drive.
This suppressive drive is then used to divide the stimulus drive to obtain the population response.
This process of division is known as normalization since it takes the original input and changes it according to the surrounding context.
The final result of the population response shows that the attended target is enhances while the other target receives a diminished response.

Attention and working memory

Working memory is a central cognitive mechanism coupled with separate stores for visuoplatial and phonological information.

Similarities between attention and working memory.

• Attention and working memory have both limited resources and capacities
• Working memory seres as an interface between perceptual input and internal representations.
• Working memory allows relevant perceptual information to be maintained over time. Attention to particular information has impact on working memory.
• Maintenance of spatial information involves covert shifts of attention.
• Visual processing at locations that have been is better than processing at locations that not have been memorized. The memorized locations are the focus of attention.

Paradigms for studying attention

Two trends that are evident:

• An emphasis on vision as a primary modality to explore models of attention.
• The rich development of experimental paradigms like ‘visual search’, ‘dual-task interference’, ‘inhibition of return’ and ‘attentional blink’ which started in single studies to later become general experimental techniques.

Visual search

The problem of how we use attention to search for a target in a visual display.

Feature integration theory (FIT)
Both target being search for and the distractor objects would be composed of visual features such as shape, size and color.
Recognition of a target is determined by two processes:

• Preattentive visual processes
  Can simultaneously analyze the entire scene and detect the presence of unique features.
  Capable of simultaneously searching the entire visual array.
  It can independently examine features (like color and form) and if the item could be identified by a simple primary feature then this preattentive stage alone could lead to recognition.
• But if recognition depends on combining multiple features then a process of focused attention is needed to combine features.
  This use of attention to ‘glue’ together the different features helps to solve the binding problem.
  Binding problem: the issue that, although perception works via analysis of separate perceptual features, our subjective experience has all these features bond together.
  Different features are not necessary processed together.

Illusory conjunctions: when the process of combining feature goes wrong. This comes about when attention is diverted or overloaded and appear as confusions between features of objects.

Model of Guided Search
Similarity with FIT: focused attention can be found in both and is important for binding features for recognition.
Differences with FIT: Although the preattentive stage still exists in the form of early visual processing, emphasis is given to how this analysis forms and abstract presentation where particular features can be used to guide attention at the point to the attentional bottleneck.
The addition of a non-selective pathway, which analyses collective aspects of the visual input to guide attention.
The guidance information is not sufficient for recognition of complex scenes or objects but can be used to facilitate processing at the attentional bottleneck. This is obtaining the gist of a scene.

One of the defining characteristics of the non-selective pathway is that it uses distributed attention.

• Allows a rapid evaluation of the entire image.
• Works by extracting statistical properties of objects and features present in the image. These statistics enable one to perceive the overall layout and structure of the image, but are insufficient to enable recognition of particular objects.
• Acts not simply by considering the image information at a coarser scale than focused attention, but rather provides a relational analysis of the whole image.
  These features include: orientation, contrast texture, size, velocity and direction of motion.

Inhibition of return

If attention is attracted to an event in the visual field there will be facilitation of processing around this location. However, after attention moves away, this location suffers from delayed responding to events. This is inhibition of return.

• The mechanism promotes searching novel locations rather than returning to one that has already been examined.
• Inhibition of return begins around 250-300 milliseconds after attention has been directed to a location and this inhibition appears to have a duration of around 3 seconds.
• It exists in locations in space and on attention directed to objects.
• It is coded in environmental coordinated rather than being fixed to the eye’s retinal coordinates.

Attentional blink

If we are watching a sequence of rapidly presented visual displays (6-20 items per second) the second of two targets cannot be identified when its presentation is close in time to that of the first target.
This is attentional blink
This notion of a blink captures the intuition that after attention has obtained the first target, it ‘blinks’ and thus does not see the second.

Failures of attention

Change blindness

The phenomenons where substantial differences between two nearly identical scenes are not noticed when presented sequentially.

Inattentional blindness

We can be looking directly at a target but will report that we do not see it if attention is not allocated.
The failure to notice a clearly visible target due to attention being diverted from the target.

Continuity editing: a film-making technique to produce a smooth continuous experience across changes in camera shot.

Consciousness

Subliminal perception: the case where a stimulus is presented below threshold but its effect on behavior can still be measured.

To be conscious is to be aware of one’s own existence as evidenced by thoughts and perception of one’s surroundings.

Functions of consciousness

The computational theory of consciousness.
What its purpose is and why it does what it does.

Does consciousness have a function?

Two distinctive views of the functions of consciousness

• Conscious inessentialism → consciousness is not necessary
• Epiphenomenalism → does not reject the existence of consciousness but holds that is has no function

Volition

Our ability to make conscious choices. If we can demonstrate volition then this demonstrates free will.
Commonly assumed function of consciousness is that it is related to our ability to choose which action to perform. There is a close causal link between our conscious experience and our actions. But! There is psychological data to question this link.

Other possible functions

It provides us with an executive summary of our current situation. Even with attention to limit input there is still a constant inflow of information form the world and any of a large number of personal desired we might wish to satisfy at any one time.
The executive summary produced by consciousness might primarily serve to integrate this vast amount of information. Conscious performing an integrative function.

Global workspace theory: consciousness requires integrations across a broad range of brain areas. Consciousness facilitates flexible context-driven behavior.
Consciousness would work across extensive brain networks with the task of creating the summary for this network.

Attention and consciousness

Attention and consciousness share the property of involving selection of particular information above other information.

• In attention the selected information receives deeper processing
• In consciousness the selected information receives privileged access to the stage of our mental life.
• In both models there is concern over the fate of the non-selected information as both unattended and non-conscious information have been found to still be able to influence behavior.

Attention and consciousness are different.

Attention does not determine whether an input reaches consciousness but rather determines whether a conscious report about the input is possible.
Different types of consciousness:

• Phenomenal consciousness: the experiential properties of sensations, feelings and perceptions. Just experience.
• Access consciousness:; representations that are broadcast for use in reasoning and control of action and can be reported.

The proposed model:
We will be phenomenally conscious of many inputs but in the absence of attention this experience will quickly fade away and become unavailable for report.
This model can be seen to act independently of awareness but is responsible for taking input form phenomenal to access consciousness.

A general framework to implement this model of attention and consciousness involves the concepts of: - a forward sweep of information. The progression of activity form input brain areas to progressively more complex brain areas.
This sweep corresponds to the unconscious where information is processed but we do not have access to these representations.

• Recurrent processing. Involves cyclic processing between brain areas such that the activity at both areas is dependent on each other.
  The feed-forward sweep will activate increasing complex brain areas that will feedback their results to lower levels, which in turn modifies activity at lower levels and the ongoing information is swept forward.
  The role of attention in this process is to provide mechanisms to bias the recurrent processing to enable selection.

Relating consciousness to brain activity

Neuropsychology

The study of split-brain patients helped immensely to understand how the different parts of the brain interacted and how to address questions of consciousness.

Neural correlates of consciousness (NCC)

Meant to make the empirical NCC approach distinct from philosophical approaches.
The essence of the approach is to examine how brain activity changes when, everything else being as equal as possible, a stimulus is experienced consciously or not.
The goal: tho find the minimal neuronal mechanisms that are jointly sufficient for a conscious percept to be obtained.
Implicit in this approach is an appreciation that experiments involving different stimuli might indicate different brain areas that are involved in conscious processing. The belief is that ultimately the results will converge upon a basis for understanding how brain activity leads to consciousness.

Binocular rivalry: arises when different images are presented simultaneously to the two eyes and results in experiencing seeing one image and the other alternately.
Humans and monkeys when presented a different image in each eye only report that one is visible at a time.
The visible image dominates the invisible one in consciousness, though both are clearly activating primary visual cortex.
In primary cortex only a small number of cells weakly modulated their activity based on what image was seen. Further into visual processing, in the inferior temporal cortex, cells were found whose activity correlated with which image the money was current aware.
Activity in primary visual cortex is necessary for consciousness to occur. But it is not sufficient on its own.