Higher Cognition 4 - Attention & Awareness PBS5

• focus
• awareness
• conscious access

• Orienting function toward environment
• Partial control of the content of consciousness
• Maintaining alertness

• Baars
• Based on observation that human brain comprises several specialised systems (for perception, attention, language etc) each of which carries out its task at a level that does not reach the threshold of consciousness.
• Consciousness becomes possible when these various subsystems pool certain results of their operations in a single, global workspace. When expressed in this forum, they become accessible to brain as a whole, and therefore conscious.
• Serves as a site for information exchange. Other subsystems can take advantage of this available info too.
• akin to a form of momentary working memory
• accounts for various evidence for interaction between conscious and unconscious processes observed in various phenomena

• Dehaene et al
• Global neuronal workspace hypothesis (GNW) - perceptual, attention, memory, value, and motor areas interconnect to form higher-level unified space where info is shared
• Pyramidal neurons of the cerebral cortex - with their long axons that can connect areas of cortex that are distant from one another
• Esp in thick layers II/III - which is particularly dense in PFC

• Baars's model simply distinguished one conscious state from multiple unconscious ones, but Dehaene's model distinguishes between 3 possible states of activation:
• 1. subliminal processing: not enough bottom-up activation to trigger wide scale activation of network
• 2. Preconscious state: enough activation to access consciousness, but is temporarily kept from doing so by lack of top-down attention
• 3. Conscious state: preconscious stimulus receives enough attention to cross consciousness threshold

• It does not select information but summarises all relevant info 
• making this compact summary accessible to other stages of cognition and brain areas 
• (eg. planning stages, detecting anomalies, decision, language, rational thought)
• This integrative aspect is emphasised by the Integrated Information Theory of consciousness (Tononi, 2004)

A mathematical model intended to describe and quantify the nature of consciousness. It is based on the idea that the consciousness of a system may be measured by the amount of integrated information.

• attention as analyser
• consciousness as a synthesiser

• No conscious/no attention: formation of afterimages, rapid vision (<120ms)
• No conscious/attention: priming, adaptation, visual search, processing of objects, blindsight

• Conscious/no attention: pop out, iconic memory
• Conscious/attention: working memory, detection of unfamiliar stimuli, full reportability

• Blindsight (De Gelder et al)
• Blindsight patients (patient TN with bilateral lesion of striate cortex - the 'where' stream through superior colliculus intact, but not 'what' stream from striate cortex - that is why it is unconscious.) 
• Can navigate a room with obstacles and avoid them without consciously realising if they are really there or what they are.
• Attention exist without awareness - exogenous
• 

• Simons & Chabris (1999) famous experiment 
• Many observers failed to see a gorilla-suited man walking past scene if they were focusing on how many passes were being made in that scene. 
• Attention to the scene, but selectively, and thus without awareness of a major change.

• The brain seems to organised in a modular fashion
• However, conscious part of the brain/mind seems to be non-modular