lecture 16 - Attention

Essential: PSYC202 Attention lecture notes.pdfAdditional:

• Corbetta & Shulman (2002)

• Knudsen EI (2018) Neural Circuits That Mediate Selective Attention

• Gazzaniga et al. (2014) Cognitive Neuroscience, 4th Ed., Chapter 7, Attention (on Moodle)

Lecture Overview

What Is Attention?

Definition: Attention is the cognitive process by which the mind selectively focuses on certain stimuli while ignoring others, allowing for efficient processing of information.William James (1890) describes attention as "...taking possession by the mind of one out of several trains of thought..." which encapsulates the essence of attention as a selective mechanism.Examples:

• Derren Brown's Person Swap: An illusion that showcases how people can miss significant events in their surroundings while focused on an act.

• The Colour Changing Card Trick: An example of selective attention where observers fail to see changes in an image due to focused attention on a specific detail.

2. Functional Significance of Attention

Selective Processing: Only a fraction of sensory information enters consciousness, leading to an incomplete perception of the environment. This selective filtering has evolutionary benefits in preventing information overload.Hoffman (2019): Evolutionarily, showing a complete representation of the world would be impractical and disadvantageous, requiring organisms to prioritize.Survival Focus: Successful organisms thrive by attending to salient stimuli essential for survival and reproduction, such as predators, food sources, or potential mates.

3. Purpose of Attention

• Finding Essential Resources: Attention is crucial for locating resources required for survival, such as food or mate selection.

• Noticing Important Cues: This includes noticing environmental signals such as temperature changes or the nuances of non-verbal communication within social contexts.

• Ignoring Non-Essential Information: The capacity to differentiate between cues, such as a baby's whimper versus a cry for help, is vital for effective functioning.

• Salience: Attention aids in prioritizing stimuli based on context, urgency, and relevance to survival needs.

4. Types of Attention

• Task Driven Attention:

  • Selective Attention: A conscious effort to focus on specific stimuli among distractions.

• Stimulus Driven Attention:

  • Reflexive Attention: An automatic response elicited by salient stimuli, often critical for survival.

  • Orienting: Involves physical shifts in focus through body movements, such as turning one’s head to hear better.

• Overt vs. Covert Attention:

  • Overt: Involves observable movements, such as eye or head movement.

  • Covert: Engaging in focus without visible movement, like concentrating on a conversation in a crowded space.

• Divided Attention: The ability to manage multiple inputs or tasks requiring attention simultaneously, presenting challenges in performance.

• Other Types: Includes focused, sustained, spatial, goal-centered, object-centered, involuntary, and divided attention.

5. Neurocognitive Attention Research

Research Questions:

• How does the brain’s neural response vary with attention?

• Which specific brain regions are responsible for controlling the focus of attention?

Measurement Techniques:

• Auditory: Techniques include dichotic listening, which examines how individuals process different auditory messages, and the cocktail party phenomenon, which evaluates selective hearing in noisy environments.

• Visual: Spatial selective attention and visual search paradigms are utilized to study how attention impacts visual processing.

Outcome Measures:

• Behavioral: Performance is often evaluated in terms of reaction times and detection accuracy in response to stimuli.

• Chronometric Analysis: EEG methodologies assess processing time, providing insights into the temporal dynamics of attention.

6. Studying Selective Attention

Visual Techniques:

• Task designs focus on covert attention where responses to attended versus ignored stimuli are compared, revealing the cognitive processes at play.Auditory Techniques:

• Dichotic Listening Tasks: Measure the brain’s responses to both attended and unattended stimuli, demonstrating the effects of selective attention across modalities.

• Active vs. Passive Tasks: Engaging attention actively requires concentration, while passive tasks involve ignoring auditory inputs during engagement with other activities. A challenge arises as these task nature differences complicate direct comparisons.

7. Effects of Attention on the Brain

• Higher Activation: Focusing attention on specific stimuli can elevate neuronal activation in particular brain areas, including the auditory and visual cortices, as well as subcortical structures such as the cochlea, midbrain, and thalamus.

• Reconfiguring Receptive Fields: Attention not only enhances neural responses but alters sensory processing in how areas interpret incoming stimuli.

8. Evidence from EEG Measurements

• Hillyard et al.: Research showed that the auditory cortex exhibits enhanced event-related potentials (ERPs) with greater amplitudes when stimuli are attended to versus ignored.

• Van Voorhis & Hillyard: In visual tasks, larger amplitudes were recorded in the visual cortex for stimuli at attended spatial locations, illustrating selective attention effects.

9. Cocktail Party Effect Studies

Real-Life Relevance: Studies highlight how individuals filter information in environments with multiple audio sources, relevant for understanding selective attention in social settings.Participant Tasks: Involve identifying specific messages based on distinct features such as color, pitch, or speaker identity.

10. Auditory Cortex Activity Modulation

• Mesgarani & Chang (2012): Neural recordings reflect that attention can modulate auditory responses based on the focus of stimuli, emphasizing the dynamic nature of attentional processing.

11. Visual Cortex Activity Modulation

• Hopfinger et al. (2000): fMRI studies revealed that selective attention activates certain areas within the visual cortex more than others, informing theories about how visual processing prioritizes spatial information.

12. Control of Attention

Neural Networks: The frontoparietal networks play a substantial role in regulating attention based on the relative salience of stimuli and the cognitive goals set by the individual.Midbrain Involvement: The superior colliculus acts as a reflexive director in spatial attention, influencing how individuals orient towards salient stimuli.

13. Attentional Control Network

Role of Thalamus: Functions as a sensory gate, while the prefrontal cortex manages inputs based on the relevance and salience of stimuli, crucial for adaptive behavior.

14. Attention Control Evidence

• Activation of different brain networks occurs depending on task demands and the salience of stimuli during focused attention tasks, showcasing the complexity of attentional control.

15. Attention and Neural Plasticity

Process: Activating attention systems enhances neurotransmitter systems, such as acetylcholine, facilitating synaptic strengthening and learning through repeated exposure and engagement with stimuli.

16. Superior Colliculus

Function: A critical hub for attention control, the superior colliculus integrates sensory signals to guide orientation responses effectively.

17. Retinotopic Mapping

Spatial Representations: Establishes a spatial mapping of sensory information to direct eye movements and saccades precisely, thus optimizing visual exploration and attention.

18. Competitive Attention Control

Spatial Map Competition: The highest priority stimulus in any context is selectively processed, which necessitates agreement among cortical networks and the superior colliculus for effective attentional deployment.

19. Summary of Findings

• Attention's Effects: Enhances neural responses to crucial stimuli while minimizing the impact of irrelevant information.

• Cortex and Midbrain Role: Effective coordination of attentional focus involves multiple brain regions such as the prefrontal cortex and superior colliculus, illustrating the integrated nature of cognitive control processes.