Lecture 15 Attention

Attention

Goals

  • Review psychological models of attention and their historical development.
  • Examine physiological studies of attention, including Event-Related Potentials (ERPs) and fMRI findings.
  • Explore the role of the thalamus in attentional modulation and sensory processing.
  • Discuss the anatomy and brain networks associated with attentional control.

What is Attention?

Attention is the cognitive process of selectively concentrating on specific information while ignoring irrelevant stimuli. It is essential for perception, memory, and goal-directed behavior.

Key Types of Attention

  1. Selective Attention:
    • Focus on specific stimuli to enhance perception and processing.
  2. Divided Attention:
    • Simultaneously managing multiple tasks or sources of information.
  3. Sustained Attention:
    • Maintaining focus over extended periods.

Costs and Benefits of Attention

  • Benefits: Faster response times and higher accuracy for attended stimuli.
  • Costs: Misdirected attention reduces performance on the task at hand.

Historical Models of Attention

Early Selection Theory

  • Broadbent (1950s):
    • Proposed a “filter” at the perceptual level that blocks unattended stimuli to prevent sensory overload.
  • Treisman’s Attenuation Model:
    • Suggested that unattended stimuli are weakened but not entirely blocked.
    • Highly salient stimuli (e.g., one’s name) can “break through” the filter.

Late Selection Theory

  • Deutsch & Deutsch:
    • Argued that all stimuli are processed at a perceptual level, with selection occurring at the response stage.

Modern Perspective

  • Attention is not rigidly “early” or “late” but operates dynamically at multiple levels depending on the task and context.

Psychological Studies of Attention

The Posner Cueing Task

  • Description:
    • Measures the effects of spatial attention on reaction time and accuracy.
    • Participants are shown a central cue (e.g., an arrow) that directs attention to a specific location, followed by a target.
    • Targets can be:
      • Valid: Appear in the cued location.
      • Invalid: Appear in an uncued location.
      • Neutral: Appear without any directional cue.
  • Findings:
    • Valid Targets: Faster reaction times and higher accuracy.
    • Invalid Targets: Slower reaction times and lower accuracy.
    • Demonstrates the costs and benefits of attention.

Feature Integration Theory (Treisman)

  • Key Idea:
    • Attention binds features (e.g., color, shape) into unified objects.
  • Experimental Evidence:
    • Simple features like color can “pop out” preattentively.
    • Conjunctions of features (e.g., a green “X” among red “X”s and green “O”s) require focused attention and result in slower detection times.

Physiological Studies of Attention

  • Hillyard Task:
    • Subjects attend to stimuli in one visual field while ignoring the other.
    • Results:
      • Attended stimuli evoke larger ERP responses, particularly at the P1 component (~100 ms).
      • Provides evidence for early attentional modulation of sensory processing.
  • Mismatch Negativity (MMN):
    • ERP component evoked by a deviant stimulus within a sequence of repetitive stimuli.
    • Reflects automatic detection of change, even without directed attention.

Neuroimaging Studies (fMRI)

  • Findings:
    • Attention increases activation in early sensory areas, such as V1, V2, and the LGN (lateral geniculate nucleus).
    • Feedback projections from cortical areas sharpen sensory processing in the thalamus.

Neural Networks of Attention

Anatomy of Attentional Control

  1. Prefrontal Cortex (PFC):
    • Directs top-down control of attention.
    • dlPFC is crucial for sustaining attention and managing competing demands.
  2. Parietal Cortex:
    • Integrates sensory information and directs spatial attention.
    • Damage to the right parietal lobe can cause hemispatial neglect.
  3. Thalamus:
    • Modulates sensory input and serves as a hub for attentional control.
    • Feedback connections from the cortex influence thalamic processing.

Thalamic Modulation

  • Lateral Geniculate Nucleus (LGN):
    • Primary relay for visual information.
    • Feedback from V1 sharpens responses, enhancing attentional focus.
  • Studies show increased LGN activation for attended stimuli, suggesting attentional filters operate at early stages.

Disorders of Attention

  • Hemispatial Neglect:
    • Patients fail to attend to one side of space, often due to damage in the right parietal lobe.
  • Anosognosia:
    • Lack of awareness or denial of deficits, commonly seen in neglect patients.

Applications and Implications

  • Cross-Modal Attention:
    • Attention can be allocated across sensory modalities.
    • Difficult tasks in one modality (e.g., visual tracking) reduce attentional resources available for another (e.g., auditory detection).
  • Practical Insights:
    • Attention is a limited resource that can be optimized for performance in real-world tasks (e.g., driving, multitasking).

Key Terms

  • Selective Attention: Prioritizing specific stimuli over others.
  • Posner Cueing Task: Measures spatial attention and its effects on reaction times.
  • Feature Integration Theory: Explains how attention binds features into coherent objects.
  • Event-Related Potential (ERP): Electrical brain response to specific stimuli.
  • Mismatch Negativity (MMN): ERP component reflecting automatic detection of deviant stimuli.
  • Hillyard Task: Demonstrates early attentional modulation using ERPs.

This summary consolidates psychological theories, physiological findings, and neural mechanisms, offering a comprehensive understanding of attention and its role in cognition and behavior. Let me know if further refinements are needed!

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