Ch. 5: Attention and Selective Processing

Chapter 5: Attention

Overview of Attention

  • Attention is defined as the ability to selectively extract information from the environment.

  • It involves controlling the orienting of one’s attention to prioritize certain perceptual inputs over others.

  • The capacity for attention allows individuals to operate across multiple sensory domains, including vision and audition.

Key Topics Covered

  • Unilateral neglect

  • Selective attention

  • Look-but-fail-to-see

  • Priming

  • Spatial attention

  • Divided attention

Unilateral Neglect

  • Definition: A failure of attention often caused by damage to the right parietal cortex, which is recognized as a strong attention center responsible for processing the left visual environment.

  • Results: Individuals with unilateral neglect ignore all inputs from one side of visual space, typically the left side. Unilateral neglect is typically caused by damage to the right parietal cortex, which leads to a failure in attention to the left side of visual space. This can manifest in several ways: - **Ignoring the left side of the visual field**: A person might only eat food from the right half of their plate, shave only the right side of their face, or dress only the right side of their body. - **Bumping into objects**: Individuals might frequently collide with objects or doorways on their left side because they are unaware of their presence. - **Lack of awareness of left-sided limbs**: They might ignore their left arm or leg, sometimes even denying that it belongs to them. - **Reading only the right side of text**: When reading, they might only perceive and process the text on the right side of a page or line. While less common and often less severe, neglect can theoretically occur with damage to the left parietal cortex, leading to a neglect of the right visual field. However, the right hemisphere plays a dominant role in attention for both visual fields, so damage to the left hemisphere typically results in less pronounced or transient neglect symptoms on the right side. If it were to occur, similar examples would apply, but mirrored to the right side of space (e.g., ignoring the right half of a plate of food, bumping into objects on their right side).

Selective Attention

  • Definition: The ability to filter out unattended information while maintaining focus on relevant stimuli.

  • It allows individuals to tune out distractions and focus on a specific target, referring to a process akin to filtering out non-targets in preference for targets (analogous to tuning into white targets, while ignoring black non-targets).

  • Cocktail Party Effect: This phenomenon delineates how semantically relevant words can "pop out" from the unattended channel, demonstrating that while some information is filtered out, a degree of retention is maintained.

  • Inhibitory Control: Selective attention incorporates the inhibition or suppression of unwanted or distracting information. Filters are established to allow relevant information to pass through while blocking irrelevant information.

  • Attentional Capture: This occurs when a salient stimulus, such as an emergency vehicle, breaches your controlled filter, warranting an automatic shift in attention. It is measured by the difference in response time (RT) when a distractor is present versus absent.

Look-but-Fail-to-See

  • Inattentional Blindness: This term refers to failing to perceive a prominent stimulus even while looking directly at it, demonstrating that perception entails more than mere sensory input.

  • Change Blindness: A related phenomenon where observers fail to notice changes in a visual scene from one instance to another, often exemplified by continuity errors in film.

  • Implication: These occurrences underscore that cognition encompasses more than visual engagement; it integrates perceptual understanding and attention, marking the limitations of what can be processed at any given time.

Priming

  • Concept: Priming relies on a network of detectors with increased responsiveness due to recent or frequent exposure. Detectors activated in the past, whether intentionally or from expectation about upcoming stimuli, tend to respond more readily.

  • Example: If searching for a friend in a crowd, prior knowledge of their outfit allows for the priming of specific detectors (e.g., those responsive to blue hats).

  • Effort and Limitations: Priming necessitates cognitive resources. Excessive priming of certain detectors can detract from the overall capacity to attend effectively, as not all detectors can be primed simultaneously.

  • Types of Priming:

    • Stimulus-driven (bottom-up): Activation based on past exposure (e.g., frequently encountered stimuli, termed exogenous attention).

    • Expectation-driven (top-down): Involves conscious control where only goal-relevant detectors are primed (termed endogenous attention).

Spatial Attention

  • Concept: Attention is often conceptualized as a “spotlight” that can be directed toward various locations in the environment.

  • Mechanisms of Shifting Attention:

    • Top-Down Signals: Arising from brain networks, particularly in the frontal and parietal cortex, that dictate how attention shifts:

    • Orienting System: Disengages attention from one target to shift to another.

    • Alerting System: Maintains a general state of alertness within the brain.

    • Executive System: Manages voluntary actions and decisions about attentional focus.

  • Deciding Points of Attention: Typically determined by:

    • Physically salient stimuli (bottom-up)

    • Expectations of relevant stimuli (top-down)

    • Individual differences as to what captures one's attention.

  • Ultra-Rare Item Effect: Rare or unusual items tend to be overlooked; this highlights the challenges in the attentional spotlight’s effectiveness.

The Binding Problem

  • Definition: A philosophical and cognitive question regarding how basic features (color, shape, motion) processed in parallel come together to form a unified perception of an object.

  • The feature integration theory, proposed by Anne Treisman and Garry Gelade, posits that early perception detects elementary features independently and in parallel across the visual field. However, focused attention is necessary to "glue" these individual features together to form a coherent, unified perception of an object, thus facilitating object recognition. This theory addresses the binding problem by suggesting a two-stage process:

    • Preattentive Stage: In this initial, automatic, and unconscious stage, basic features such as color, shape, orientation, and motion are encoded and processed separately across the entire visual scene. During this stage, features are "free-floating" and not yet associated with a specific object.

    • Focused Attention Stage: During this second stage, conscious and focused attention is directed to a specific location or object. This "attentional spotlight" acts to bind the elementary features that are present at that location into a coherent whole. For example, if you see a red square and a blue circle, focused attention on the red square binds the feature "red" with the feature "square" to perceive a red square.

    • Implications: Without focused attention providing this "glue," features can sometimes be miscombined, leading to illusory conjunctions, where participants might report seeing a "red circle" when presented with a red square and a blue circle. The theory highlights that attention is crucial not just for selection, but also for the perceptual construction of objects from their constituent features

Divided Attention

  • Definition: The ability to attend to more than one stimulus or task simultaneously.

  • Difficulty of Divided Attention:

    • Divided attention can be straightforward in some contexts while challenging in others (e.g., multitasking with overlapping cognitive demands leads to greater difficulty).

    • Interference occurs when tasks compete for the same cognitive resources, particularly when resource demands overlap (e.g., listening to a podcast while watching TV).

  • Factors Influencing Divided Attention:

    • Executive control is paramount and varies based on the cognitive load of the tasks at hand. Higher loads necessitate more executive control, restricting attention available for additional tasks.

Key Terms

  • Unilateral neglect

  • Selective attention

  • Attentional filtering

  • The cocktail party effect

  • Attentional capture

  • Inattentional blindness

  • Change blindness

  • Feature priming

  • Spatial priming

  • Priming costs

  • Attentional "spotlight"

  • Ultra-rare item effect

  • Feature integration theory

  • Divided attention

  • Executive control