Cognitive_Week_3

Chapter Overview

  • Title: Attention

  • Author: Mangun

  • Source: Cognitive Neuroscience, 5th Edition, W.W. Norton & Company, 2019

Big Questions

  • Does attention affect perception?

  • To what extent does our conscious visual experience capture what we perceive?

  • What neural mechanisms are involved in the control of attention?

Today's Topics

  • Importance of attention

  • The cocktail party effect

  • Early vs. late selection theories

  • Endogenous vs. exogenous attention

  • Inhibition of return

  • Types of attention: Spatial, feature, and object attention

  • Experimental evidence for attention

Importance of Attention

  • Definition: Attention is the process by which the mind chooses from among various stimuli that strike the senses at any given moment.

  • Involves processing from auditory, sensory, and visual cortices.

Cocktail Party Effect

  • Refers to the ability to focus on a single conversation while filtering out background noise.

Early vs. Late Selection Models

  • Early Selection: Filtering occurs at early processing stages due to the overwhelming influx of sensory information. Only relevant stimuli are processed in detail.

  • Late Selection: Filtering occurs at later stages, allowing for the identification of irrelevant but salient stimuli (e.g., hearing one's name).

Evidence for Early Selection

  • Neurophysiological Study: In a study with cats, recordings from the cochlear nucleus showed greater response to sounds when the cat focused on a relevant stimulus (e.g., a mouse) compared to when it was not attending.

  • Dichotic Listening: Involves two separate auditory streams; individuals typically repeat the attended stream only, but can be diverted by salient stimuli such as their own name.

Experimental Evidence

Event-Related Potentials (ERP)

  • Dichotic Listening Task: Measured amplitude response to attended versus unattended inputs, showing early selection effects.

  • Mapping Attention Effects: Topographic maps demonstrated that auditory attention modulates signals in the primary auditory cortex early in processing.


Differences in Types of Attention

  • Exogenous Attention: Automatic, transient, bottom-up attention to salient stimuli from the external environment.

  • Endogenous Attention: Willful, sustained, top-down attention that is voluntarily directed by the individual.

Spatial Attention Studies

  • Valid-Invalid Cueing Task (Posner): Involves cues predicting where stimuli will appear; faster reaction times correspond to valid cues due to endogenous attention.

ERP Studies on Endogenous Visuo-Spatial Attention

  • Show increased voltage response how covert attention affects sensory processing in the brain for attended vs. ignored stimuli.

Object-Based Attention

  • Effects Demonstration: Reaction times show that attention is faster to targets on the same object than to targets on different objects, revealing the automatic spread of attention across objects.

Feature-Based Attention

  • Described as attention to specific stimulus features represented in distinct brain areas (e.g., motion in MT, color in V4).

Retinotopic Mapping for Attention

  • Retinotopic Mapping: The orderly representation of external visual space in the brain allows for delineation of cortical areas affected by attention.

Summary of Key Points

  1. The cocktail party effect indicates that attention can selectively filter relevant stimuli from irrelevant background noise.

  2. Early selection theories suggest that attention filters information at early processing stages.

  3. Evidence from neurophysiological and ERP studies supports the existence of early selection mechanisms in attention.

  4. The distinctions between endogenous and exogenous attention are crucial for understanding the neural processes underlying attentional control.