PSYC513 Lecture 4 Part 2 Notes

Contact Information

• Email: matt.roser@plymouth.ac.uk

• Office: PSQ B207

• Office Appointment:

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  • Thursday 10-11am

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• Dr. Matt Roser

Lecture 4: Part 2. Consciousness

• Chapters 12 and 13 from Baars & Gage (2018). Fundamentals of cognitive neuroscience: a beginner's guide.

• Optional reading: Flanagan, O. J. (1984). The science of the mind. Cambridge, MA: MIT Press.

Today’s Lecture

• Historical views: dualism and monism

• Modern concepts of consciousness: access, qualia and the easy and hard problems

• Mind and Brain: Modern investigations/theories

• Disturbances of consciousness

Historical Views of the Mind and Body

• Rene Descartes (1596 - 1650)

Why Descartes?

• Formulated ideas on fundamental topics relevant to modern psychology

  • Nature of the mind

  • Control of behavior

• Central to the development of science of natural processes

• The big questions are still unanswered – i.e., the ‘Mind-Brain problem’

• His views still find supporters, although they are anathema to the modern scientific approach

The Mind and Body Before Descartes

• Aristotle:

  • Soul is the essence of being

  • No distinction between mind and body

  • Mind centered on heart

• Galen:

  • Pneumatic theory of brain

  • Ventricles

  • Animal spirits

• Vesalius:

  • Predecessor of Descartes

  • Increased knowledge of human anatomy

Descartes’ Mechanistic View of Behavior

• 1662 - Descartes’ De Homine (Treatise of Man) published posthumously, outlining the role of ‘animal spirits’ in reflex action.

• 1663 – Descartes’ works placed on the Vatican’s index of banned books

• To the Church, Descartes had dangerously promoted the possibility of a science of the mind

• Ironically, Descartes would have disagreed – ultimately the mind would not yield to science

A Mechanistic View of Behaviour

• Descartes implied that the vast majority of human behaviors (all except those involving the soul) had analogies in the activities of animals and could therefore be studied through the investigation of animal behavior.

• If behavior was fundamentally mechanical, it could be understood and its causes should be rational and lawful

• Inspired by 17th Century automata

A Mechanistic View of Behaviour

• Descartes’ Reflex Mechanism

  • Directly analogous to automata

  • Fully explains animal behaviour

  • Provides a model for the workings of the body

  • Explains some human behavior - nonconscious

  • Doesn’t apply to the workings of the soul (mind)

The Soul / Mind and the Brain

• Cartesian Dualism – mind and body are separate realms

• Body is an ‘earthen machine’ – banished vital spirits etc (replaced mystical action with mechanical)

• Mind is essential to our being in a way that body is not

• Different properties – extension vs nonlocalized, deterministic v unbounded

• Existence of the soul is indubitable – ‘Cogito, ergo sum’ A universal intuition, from introspection

• ‘But what then am I? A thing which thinks. What is a thing which thinks? It is a thing which doubts, understands, conceives, affirms, denies, wills, refuses, which also imagines and feels.’

Conditioning (Pavlov) and Behaviourism

• Studied stimulus-behaviour links

• Denied mentalism

• Mind existed as series of stimulus- response contingencies

• Extension of Descartes’ Mechanistic View …to behaviour …and to Mind

• ‘Cognitive Revolution’ – 1960’s

• Inferred mentalistic structures with parts and connections

Reject Dualism and take a Monist/Materialist stance

• Mind is brain

• Psychological phenomena are to be accounted for as the effects of organic changes in the brain and nervous system

• Modern perspectives:

  • Conflicting Viewpoints on Mind and Body

  • Descartes: We may be just minds that construct the illusion of the body

  • Modern cognitive neuroscience: We may be just bodies that construct the illusion of a mind

Modern perspectives: What is Consciousness?

• Awakeness versus sleep

• General alertness (versus generally inattentive)

• Focal attention (versus distraction)

• Reflective, reportable state (metacognition)

• Self-awareness (self-consciousness)

• Qualia (subjective experience)

• 1-5 can be examined by cognitive neuroscience

• Phenomenal consciousness

• Access consciousness

Three Tractable Characteristics of Consciousness

• Operationalized: Can it be defined and observed in objective terms?

• Implementation: Can we find ways to implement it in an artificial neural network?

• Adaptivity: Is there an evolutionary function?

Consciousness & the Brain

• Differences in brain processes for consciously perceived v non-perceived stimuli (Moutoussis & Zeki, 2002).

• Brain activations in response to stimuli that are not consciously perceived.

• Colour-reversed faces are displayed separately to the two eyes, binocular fusion occurs, and subjects report seeing only the colour that results from the combination of the two stimulus colours

• The face or house stimuli become invisible but stimulus-specific areas of the brain are still activated.

• Why then are some stimuli consciously perceived and some not?

Models of Consciousness

• Activations associated with perceived stimuli were many times more intense than those seen with unperceived stimuli and were accompanied by activity at additional sites.

• Processing of a stimulus may reach consciousness only if it is integrated into a large-scale system of cortical activity (global neuronal workspace)

• Attentional amplification (Pre-frontal cortex) leads to interaction of modular processes allowing information to be maintained and influence other processes.

• Consciousness, at any point in time, is a global pattern of activity across the brain

• A hypothetical network for integration of local processes into a global ‘workspace’ that represents consciousness – From Dehane & Naccache, 2001. Cognition.

Brain Lesion Patients

• Fractionated consciousness suggested by lesion patients

• Damage reduces function (deficit) and it can also reduce awareness of that deficit

• Blindsight – residual visual function, residual consciousness

• Anosognosia for hemiplegia and neglect – confabulation to interpret the world in a way consistent with conscious experience.

• This is empirical evidence against Descartes’ intuition about the enduring nature of the mind following change to the body (brain)

• Evidence against Descartes’ intuition that the mind is unitary

• A global neuronal workspace explanation: A neglect patient may not be aware of his or her deficit because the mechanism linking local processing to global patterns of activation has been disrupted.