Questions: Global Workspace Theory and Neural Implementation

Question 1

A brain imaging study shows that both conscious and unconscious stimuli produce immediate activation in visual cortex, but only conscious stimuli produce a widespread surge of frontoparietal activation around 300ms later. A student concludes that visual cortex activity is the neural correlate of consciousness. What does GWT actually say?

• A. The student is correct — visual cortex activation is the seat of conscious experience
• B. Visual cortex activity is unconscious; consciousness arises only when that activity triggers ignition and global broadcast across frontoparietal networks
• C. The 300ms delay proves frontoparietal activation is a consequence of consciousness, not its cause
• D. Both conscious and unconscious stimuli produce identical brain activation — only behavioral response differs

Answer: (B)

GWT holds that early local activation in sensory cortex represents *unconscious* processing. Consciousness corresponds to 'ignition' — when that local activity crosses a threshold and triggers a self-sustaining reverberant loop that propagates broadly to frontoparietal regions and back. The 300ms late surge is the ignition signature GWT predicts. Option A is the classic error: conflating sensory processing with conscious experience.

Question 2

According to GWT, why can conscious attention only hold one thing at a time?

• A. Visual cortex can only process one stimulus at a time due to limited processing speed
• B. Global broadcast is an all-or-nothing ignition — only one representation can dominate the workspace and be broadcast globally at a time
• C. Prefrontal cortex actively inhibits all competing unconscious representations simultaneously
• D. Consciousness requires sensory modalities to synchronize their outputs, which is too resource-intensive for multiple objects

Answer: (B)

On GWT, the capacity limit of attention follows directly from the structure of ignition: when a representation ignites and propagates globally, it tends to suppress competing representations from reaching ignition threshold. The workspace broadcasts one 'item' broadly while other processing remains local and unconscious. This explains inattentional blindness — you can be fully processing a stimulus without it igniting into conscious availability.

Question 3

According to GWT, unconscious processing in specialized modules can influence behavior even without those representations reaching the global workspace.

• T. True
• F. False

Answer: True

This is central to GWT's value as a theory. Modular unconscious processing continuously runs in parallel — visual cortex computes motion, shape, and color; auditory cortex processes pitch and location — and these outputs influence priming, motor responses, and other behavior. The global workspace is not needed for these influences; it is specifically required for the flexible, reportable availability that characterizes conscious experience.

Question 4

In GWT, stimuli that fail to reach consciousness produce no neural response at most.

• T. True
• F. False

Answer: False

Unconscious stimuli produce robust early, local neural activation in sensory areas — they simply fail to trigger the ignition cascade that propagates activity globally. This is precisely what EEG masking studies find: unconscious stimuli generate normal early visual responses but lack the late (>300ms) widespread frontoparietal surge. The distinction is between local modular activation (present for all stimuli) and global broadcast (present only for conscious ones).

Question 5

Why is the 'ignition' metaphor apt for GWT's account of consciousness, and what does it explain about attentional capacity limits?

Model answer: Ignition captures the threshold and all-or-nothing character of consciousness in GWT: just as ignition either catches or doesn't, a neural representation either triggers self-sustaining reverberant activity across frontoparietal networks or fails to — there is no partial broadcast. This binary quality explains attentional limits because once one representation ignites and propagates globally, it tends to preempt competing representations from reaching threshold, so only one 'item' dominates the workspace at a time.

The metaphor is also apt because ignition propagates — it doesn't just stay at the source. The frontoparietal networks send projections back to sensory cortex and forward to all connected areas, creating widespread synchronized activity. This propagation is what makes the information 'globally available' to memory, language, motor planning, etc. Anesthesia disrupts precisely this propagation: sensory cortex still activates but the cascade fails to spread, explaining unconsciousness during surgery despite intact sensory processing.