Week 3 - Consciousness

Pinker’s 3 words on consciousness

• Sentience = subjective experience or phenomenological awareness (eg, animals probably have this)

• Access to information = the ability to report our subjective experience (verbally reportable)

• Self-awareness = I can think to myself, I can feel pain… (narrative self)

Humphrey

“construction of the narrative self is adaptive because it helps us navigate the social world. It is a consequence of having developed theory of mind”

Velmans

• what we think of the “outside world” is a stream of visual consciousness, inside of our physical skull

• all visual experience is as ‘internal’ as a dream

• when we are awake, the dream is systematically constrained by information coming in from the sense organs

Chalmers

• famous for distinguishing between easy + hard problems of consciousness

• the easy problems are to do with the functions which are carried out by conscious brain systems

• the hard problem is why it’s not all conscious - most things that happen in the nervous system work unconsciously

Theory of Apparent Mental Causation - Wegner

• definition = we experience conscious will when we interpret our thoughts as causing our actions, even if they don’t

• priority = thought occurs before actions

• consistency = thought matches action

• exclusivity = no obvious alternative cause

• evidence = Wegner & Wheatley’s I Spy Experiment demonstrated an illusion of conscious control

Wegner’s I spy experiment

• Procedure = ppt + confederate shared control of a computer cursor

• ppts heard object names through headphones

• confederates secretly forced the cursor to stop on certain objects

• ppts rated how intentionally they felt they had caused the stop

• Findings = ppts reported greater feelings of control when they heard the object’s shortly before the cursor stopped on it

• this occurred even when the confederate actually caused the stop

• Conclusion = demonstrates the illusion of conscious will

• conscious thoughts can create a feeling of control without actually causing the action

Evaluation of Wegner’s I Spy experiment

Strength = experimental control - researcher controlled when ppts heard words + when the cursor stopped, helping the establish cause and effect

Limitation = low ecological validity - moving a cursor around a screen is artificial and may not represent real-life decisions

Libet et al - Readiness Potential Experiment

• investigated whether brain preparation begins before conscious intention

• Procedure = ppts voluntarily flexed their wrist whenever they wanted

• EEG recorded brain activity

• ppts used a clock to report when they first became aware of intending to move

Findings:

• Readiness potential (RP) = 550 ms before movement

• Conscious intention = 200 ms before movement

• Brain preparation began = 350 ms before reported conscious intention

Conclusion:

• unconscious brain activity can precede conscious awareness of intending to act

• challenges the idea that consciousness always initiates voluntary actions

• Libet proposed the conscious veto (free won't ) - consciousness may still stop an action

Libet et al - Readiness Potential experiment - Evaluation

Strengths:

• Objective measurement = EEG provided measurable evidence of brain activity before movement

• Experimental control = researchers could compare the timing of neural activity, reported intention and movement

Limitation:

• Subjective reporting = ppts may inaccurately recall when they first intended to move

• Low ecological validity = simple wrist movements don’t represent complex real-life decisions

Soon et al - MVPA Experiment

• investigated whether brain activity predicts choice before conscious awareness

Procedure:

• ppts freely chose to press a button with their left or right hand

• fMRI measured brain activity

• MVPA (multivoxel pattern analysis) analysed brain activity patterns to predict their choice

• ppts reported when they became consciously aware of deciding

Findings:

• brain activity predicted left/right choices up to 7-10 seconds before conscious awareness

• prediction accuracy was approx 60%

Conclusion:

• unconscious brain activity contains info about future decisions before conscious awareness

• challenges the idea that consciousness always initiates decisions

• does NOT PROVE free will is an illusion - predictions were not completely accurate

Soon et al - Evaluation

Strengths:

• objective measurement - fMRI measured brain activity, while MVPA identified patterns predicting decisions

• predictive evidence - brain activity predicted choices before conscious awareness, extending Libet’s findings

Limitations:

• low prediction accuracy - only 60% accurate, so decisions weren’t fully predictable

• low ecological validity - simple left/right button presses may not represent complex real-life decisions

Brass + Haggard’s What, When, Whether model

Voluntary action involves three components:

• WHAT action to perform

• WHEN to perform it

• WHETHER to perform or inhibit it

• these involve premotor brain circuits

Qualia - and how can consciousness be measured?

• Qualia = the subjective qualities of conscious experience (eg, feeling pain)

• they cannot be measured directly, so researchers use verbal reports and subjective judgements as indirect measures

Dahaene et al - Brain areas associated with consciousness

Procedure:

• researchers compared brain activity when ppt processed words consciously visible versus unconsciously (masked)

• brain imaging measured which areas were activated

Findings:

• unconscious words = more restricted brain activation, particularly in visual processing regions

• conscious words = more widespread activation across multiple brain areas

Conclusion:Re

• conscious awareness is associated with widespread brain activity rather than one isolated brain region

• this supports the idea that consciousness involves distributed brain networks

Rees - Which brain areas are associated with shifting conscious visual awareness?

• superior parietal + dorsolateral prefrontal regions are associated with shifts in visual awareness, suggesting that the attention- related brain networks contribute to conscious perception

Hemispatial Neglect - What it tells us about consciousness

• damage to right parietal lobe can cause neglect of the left side of space, despite some visual processing remaining intact

• shows that visual processing does not guarantee conscious awareness

Kiefer + Brendel’s findings on unconscious processing

• subliminal words produced meaning-related ERP responses without conscious awareness, showing that semantic processing can occur unconsciously

Global Neural Workspace Theory

• most information is processed unconsciously and locally

• selective attention allows info to enter a global workspace, where it is integrated and shared across brain systems, producing conscious awareness

Dehaene + Naccache’s theory - 3 states

• conscious = sufficient visual processing + attention

• preconscious = sufficient processing but insufficient attention

• subliminal = insufficient processing for awareness, even with attention

Evaluation of the theories of consciousness

Strength = evidence supports the importance integration across brain regions

Limitations:

• neither explains why neural activity produces subjective experience (hard problem)

• research mainly focuses on visual consciousness

Jiang et al - Attention and Consciousness

• using continuous flash suppression, they found that unseen images could influence spatial attention

• suggests that attention can operate without conscious awareness

Tononi and Koch - What is Cortical Integration & why is it important for consciousness?

• cortical integration = combining info processed in different brain regions into one unified conscious experience

• different cortical areas process separate features, such as colour, shape, motion

• the brain integrates these features so we perceive a whole object rather than separate characteristics

• eg = we consciously perceive a red moving car as one object rather than separately experiencing its colour, shape, movement

• conclusion = consciousness is associated with coordinated info processing across distributed cortical regions

Melloni et al - Neural Synchronisation

• neurons produce rhythmic electrical activity called neural oscillations

• neural synchronisation occurs when activity across brain regions becomes coordinated in time

• found that consciously perceived stimuli were associated with increased synchronisation of neural activity, particularly in the gamma frequency range, measured using EEG

• Conclusion = synchronisation may help different brain regions communicate and integrate info during conscious perception