Topic 5-attention

• Attention: given limited capacity to process competing options, attentional mechanisms select, modulate, and sustain focus on information most relevant for behaviour
• Source:

  1. Exogenous (in the environment)
  2. Endogenous (in the mind)
• Target:

  1. External (sensory information)
  2. Internal (mental representations)
• Type:

  1. Overt (involves actual movement of the sensory surface)
  2. Covert (does not involve actual movement)
• Type:

  1. Transient (momentary focus on something)
  2. Sustained (prolonged focus on something)
• Type:

  1. Selective (focus on one thing)
  2. Divided (try to focus on multiple things simultaneously)
• Dichotic listening:

  • endogenous (attend to the left ear)
  • external (sounds entering ear
  • covert
  • sustained
  • selectve
• Broadbent's filter model:

  • Cherry (1953)
  • could report existence of message, could NOT report content
• Treisman's attenuation theory:

  • Moray (1959)
  • could report change in gender and pitch, but not repeated words
  • Gray (1960)
  • meaning of unattended words being taken into account
• Late selection model:

  • McKay (1973)
  • meaning of biasing word in unattended ear affected participants' choice
  • participants were unaware of presentation of biasing words
• Event related potentials (ERPs):

  • EEG
  • non-invasive technique
  • measures surface electric fields
  • high temporal resolution, low spatial resolution
  • average of EEG signals
• Attentional stream paradigm:

  • random sequence of auditory pips
  • occasional deviant targets
  • instructed to attend to one ear
  • Results:
  • no effect of attention on brainstem evoked potentials
  • small effect on midlatency potentials
  • large effect on late waves
• Posner's orienting task:

  • endogenous
  • external
  • covert
  • transient
  • selective
• Location of visual attentional effects: lateral geniculate nucleus
• Visual attention and V4 neurons:

  • orientation tuning curve
  • attention causes gain but no change in feature selectivity
  • Attention enhances signal to noise ratio
  • no contrast: small response, small change
  • subthreshold: medium response, big change
  • high contrast: big response, small change
• Visual attention to objects: fusiform face area (FFA)
• Synchronization:

  • attention to a stimulus increases synchronization between brain areas representing that stimulus
• Unilateral (hemispatial) neglect:

  • a deficit in perceiving and responding to stimulation contralateral to damaged hemisphere
  • cannot be explained by primary sensory or motor disturbance
  • a deficit of attention
  • most often, left side neglect after damage to right parietal lobe
• Neglect can occur in multiple reference frames:

  • spatial (location based attention)
  • object based
• Role of frontal eye fields:

  • FEF stimulation enhances V4 response, only when stimulus occurs in V4 receptive field
• Change blindness: change in a picture or scene over time are not immediately apparent if not attended to
• The ability to actively direct your attention to a particular location is an example of voluntary (endogenous) attention
• Top-down: we deliberately focus on a feature on the environment

  Bottom-up: our attention jumps to unexpected features of the sensory environment
• Tempoparietal junction: involved in shifting attention between stimuli