Published on

Attention Part 2

Table of Contents

Selection Models Continued

The Deutsch-Norman Selection Model

  • This model suggests that there is an initial phase where all incoming information is processed at a low level, unconsciously.
  • The critical selection process, according to this model, occurs at a later stage based on the meaning of the information—its semantic content.
  • Essentially, the model posits that we are always processing information at some level, but we only become consciously aware of this information if it passes through this late-stage filter.
  • Therefore, what enters our conscious awareness is determined by semantic factors during this late processing stage.

Untitled

Current Findings of Selection

  • Currently, psychological research posits that there is psychological and neural evidence for both early and late selection.

Attention Blindness

  • Change Blindness: This phenomenon occurs when an individual does not notice a change in a visual stimulus.
    • The underlying assumption of the brain is that scenes are generally stable and do not change without a trigger, such as motion.
    • Change blindness exemplifies the selective nature of visual attention, highlighting that only items deemed important by an individual are likely to be noticed.
    • Focused attention is needed to notice that the feature is changing over time.
  • Inattentional Blindness: This refers to the failure to perceive a new and unexpected item that is in plain sight.
    • Even direct visual contact with an object does not guarantee that it will be consciously registered.
    • This kind of blindness is often due to attention being deeply engaged with another complex task, thus limiting the cognitive resources available for processing unanticipated stimuli. (Does not occur with change blindness)
    • Unless an item is really distinct, you need focused attention to perceive the object.

Distracted Driving

  • When you use your phone, handsfree, or any sort of device while driving, your attention is divided between the road and the task making you more likely to crash while driving.
  • Mind-wandering may also be to blame because it divides your perception.

Disjunctive Search (Feature Search, Parallel Processing)

  • This type of search, also known as a feature search, involves looking for a single unique characteristic (feature) that differentiates the target from all distractors.
  • The target item is defined by a single attribute, such as a specific color, shape, or orientation.
  • For example, trying to find a red circle among green circles; the red color alone is sufficient to identify the target.
  • Disjunctive searches typically involve parallel processing, where multiple items or the entire field of view can be scanned simultaneously, often leading to faster identification of the target.

Conjunctive Search (Narrowly, Serial Processing)

  • In a conjunctive search, the target is defined by the combination of two or more features, necessitating a conjunction of attributes for it to be identified.
  • The target shares individual features with different distractors, making it less distinct compared to any single distractor item.
  • This type of search usually requires serial processing, meaning items are scanned one after another until the target is found. This process is typically slower and more effortful than disjunctive searches.
  • The difficulty level in conjunctive searches can increase with the number of items (set size) and the similarity between the target and distractors.

Feature Integration Theory (Treisman)

The Feature Integration Theory, proposed by Anne Treisman and Garry Gelade in 1980, suggests a two-stage process of visual object recognition:

  1. Pre-attentive Stage:
    • Objects are analyzed into separate features.
    • Features like color, shape, or size pop out effortlessly during disjunctive searches.
    • This stage operates automatically and in parallel across the visual field.
  2. Focused Attention Stage:
    • Here, the features identified in the pre-attentive phase are combined or conjoined, leading to a full, integrated perception of the object.
    • This is necessary for tasks like conjunctive searches, where different attributes of an item must be combined.
    • It's a serial process, with attention acting as the binding agent, or the "glue," that associates spatially disparate features.

An implication of this theory is that without the appropriate focus of attention, our perception might create incorrect illusory conjunctions, or incorrect combinations of features. For instance, if briefly shown a red square and a green circle simultaneously, we might mistakenly report seeing a green square due to these illusory conjunctions.

Illusory Conjunction Errors

  • If attention is required to conjoin features based on the feature integration theory, not having attention might lead to incorrect illusory conjunctions.

Types of Attentional Control

Understanding how we control or direct our attention is crucial. Typically, there are two primary mechanisms:

  1. Endogenous Attention:
    • This is voluntary or top-down attention.
    • It's driven by internal processes or the individual's goals. For example, when you decide to focus on reading a book, ignoring background conversations.
    • Supported by the dorsal attention network.
  2. Exogenous Attention:
    • This is involuntary or bottom-up attention, which is stimulus-driven.
    • It's typically reactionary in response to external events or stimuli, like when a sudden loud noise captures your attention.
    • Supported by the ventral attention network.

The Posner Cueing Task

  • Subjects are presented with a central cue and with a peripheral cue, and participants will respond to how quickly they identify where the cue is.
  • The central cue triggers endogenous attention.
  • The peripheral cue triggers examples of exogenous attention.
  • There is fMRI evidence for space-based attentional control, suggesting that different parts of the brain are activated based on where you are attending to, using contralateral processing principles.

Hemi-Spatial Neglect

  • Hemi-spatial neglect is a neurological disorder where a person does not attend to stimuli or parts of stimuli on the opposite side of where brain damage has occurred, often disregarding the contralesional side.
    • It is most commonly associated with damage to the right parietal lobe. Patients with right parietal lobe damage tend to neglect the left side of space, known as the contralesional side.
  • The right parietal cortex is unique in that it has a role in attending to both the left and right visual fields. Conversely, the left parietal cortex is primarily involved in attending to the right visual field.
  • Therefore, damage to the right parietal lobe can cause a more severe and extensive neglect than damage to the left parietal lobe.

Neglect and Attention Bias

  • Attention bias refers to the tendency of patients with hemi-spatial neglect to pay attention to the ipsilesional side (the same side as the lesion) and ignore the contralesional side.
  • Despite the apparent neglect of one side, these patients often demonstrate a form of implicit awareness. This suggests that on some level, the brain is still processing information from the neglected side, but this processing does not reach conscious awareness.

Evidence from Experiments

  • In an illustrative experiment, patients with hemi-spatial neglect were asked to choose between two houses, one of which had a fire depicted on the neglected side.
  • A majority chose the house without the fire, indicating that they had unconsciously processed the dangerous cue without being consciously aware of it.

Nature of Deficits

  • The deficits seen in hemi-spatial neglect are not due to a loss of sensory perception but rather a loss of attention.
  • Neglect can manifest in relation to different frames of reference, such as personal (body-related), peripersonal (within arm's reach), or extrapersonal (beyond arm's reach) space, reflecting a complex interaction between spatial attention and cognitive processing.
Authors