Understanding Consciousness: Insights from Neuroscience and Psychological Science
This chapter explores the complexities of consciousness, including its definitions, variations, and underlying brain activity. The text discusses case studies of patients like Erik Ramsey, who, despite being in a coma, may retain awareness. It delves into the split-brain phenomenon, illustrating how different brain hemispheres contribute to our conscious experiences. Additionally, it highlights the impact of unconscious processes on behavior and decision-making. The chapter also defines sleep as an altered state of consciousness and discusses circadian rhythms and common sleep disorders.
Understanding Consciousness: Insights from Neuroscience and Psychological Science
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Presentation Transcript
Gazzaniga • Heatherton • Halpern Psychological Science FOURTH EDITION Chapter 5 Consciousness ©2013 W. W. Norton & Company, Inc.
Consciousness • Erik Ramsey is “locked in…” • Suffered traumatic injury to his brain as the result of an automobile accident • He can see, hear and feel, but he cannot move or communicate with the outside world…at least not yet
Consciousness • In a coma, but aware • Patterns of brain activity in a coma sufferer were similar to patterns found in those not in a coma (Owen et al., 2006) • Communication may be possible with coma patients previously believed to be unreachable
5.1 What Is Consciousness? Learning Objectives • Define consciousness. • Identify varied states of consciousness. • Summarize research findings on consciousness and “the interpreter” among individuals with split brain. • Discuss how unconscious processes influence thought and behavior.
What Is Consciousness? • People can be conscious even when they appear not to be • All conscious experience is associated with brain activity • Variations in consciousness occur naturally • Consciousness can be manipulated • Conscious experience varies from person to person
Consciousness Is a Subjective Experience • Consciousness: The subjective experience of the world, resulting from brain activity • The brain and the mind are inseparable • Each of us experiences consciousness personally • We cannot know if two people experience the world in exactly the same way
There Are Variations in Conscious Experience • Sleep/wake cycle • Automatic tasks • Driving, walking, catching a baseball • Controlled processing • Helps us perform in complex or novel situations
Extreme States • Conditions of impaired consciousness provide useful points of contrast to “normal” (fully-functioning) consciousness • Persistent vegetative state • Full coma that lasts more than a month • Terri Schiavo • Minimally conscious state • Deliberate movement and communication are possible • Jan Grzebski
Brain Activity Gives Rise to Consciousness • Psychologists can examine and measure consciousness (e.g., fMRI) • Consciousness arises from brain circuits’ activity
The Global Workplace Model • In some cases brain-injured patients are unaware of their deficits (“hemineglect”) • Consciousness arises through brain processes that are active at any point in time • No single area of the brain responsible for general “awareness”
The Split Brain • Awareness of the world is associated with functioning in different parts of the brain
The Split Brain • Corpus callosum removed • Two halves of the brain cannot receive information directly from each other • Studies show the relation between specific brain regions and conscious experience • Early observations were that split-brain patients had no discernable problems • Sperry & Gazanniga’s (1960s) research proved otherwise
The Split Brain • Language center located in left hemisphere • Split brain patients cannot report on an object presented in their left visual field • They could correctly choose the object (with their left hand) • Right hemisphere handles spatial tasks • Split-brain patients could not arrange blocks correctly when using their right hand • Left-handed, the task was effortless
The Interpreter • The left hemisphere attempts to make sense of right-hemisphere actions
The Interpreter Speculates • The left hemisphere tries to make sense of the world (e.g., imposing narrative structure, seeking patterns) • The right hemisphere simply experiences the world • Brain hemispheres work together to construct our experience of the world
Unconscious Processing Influences Behavior • We are aware of some mental processes and unaware of others • Subliminal perception: Processing information by sensory systems without conscious awareness • Freudian slip: An unconscious thought expressed at an inappropriate moment • Stereotype activation: Is it automatic? • Bargh et al. (1996) found research participants primed with stereotypes about the elderly unconsciously behaved in ways consistent with those stereotype
The Smart Unconscious • Good advice: “You’d better sleep on it.” • Unconscious processing of problems can lead to superior solutions (Dijksterhuis, 2004) • Even conscious thinking can undermine good decision- making (Wilson & Schooler, 1991)
5.2 What Is Sleep? Learning Objectives • Describe the stages of sleep. • Identify common sleep disorders. • Discuss the functions of sleep and dreaming.
What Is Sleep? • Sleep is biologically regulated • Circadian rhythms • Melatonin secretion linked to light-dark cycles • Some adults report needing 7-9 hours a night • 70-year-old “Miss M.” gets by on one hour per night!
Sleep Is an Altered State of Consciousness • Sleep: Awareness of the outside world is turned off (mostly) • So why don’t we fall out of bed? • EEG: The brain is active in sleep
Stages of Sleep • Sleep is not an “on-off” event • Sleep stages • Historically: 5 distinct stages • Currently: Stages 3 & 4 are now joined
REM Sleep • The sleep cycle reverses after about 90 minutes • Enter REM (paradoxical) stage • Most dreaming occurs in REM sleep • Amount of time spent in REM increases • Cycle through this pattern around 5 times per night
Sleep Disorders • Insomnia: Difficulty falling or staying asleep • Obstructive Sleep Apnea: Breathing may stop hundreds of times per night • Narcolepsy: Sufferers unexpectedly fall asleep • REM Behavior Disorder: Sufferers act out their dreams • Somnambulism: Sleep walking
Sleep Is an Adaptive Behavior • Sleep serves important biological purposes: • Restoration • Circadian rhythms • Facilitation of learning
Restoration and Sleep Deprivation • Restorative Theory: Sleep allows the body to rest and repair itself • The evidence: • Sleep increases after strenuous physical activity • Growth hormones secreted in sleep • Replenishes the brain’s energy stores • Strengthens the immune system
Restoration and Sleep Deprivation Effects of sleep deprivation: • Mood problems (e.g., irritability) • Decrements in cognitive performance (e.g., attention and short-term memory lapses) • May compromise the immune system • Falling asleep for a few seconds to a minute (microsleeps) can impair ability to perform critical tasks (e.g., driving)
Circadian Rhythms Circadian rhythm theory: • Many creatures are quiet and inactive during the night because darkness is the time when danger is highest • Reduced risk of exposure to predators • Humans: Are adapted to sleep at night because our early ancestors were more at risk in the dark
Facilitation of Learning Sleep: Strengthens neural connections needed for learning to occur • Research shows memory in participants who slept was greater than those who didn’t (Drosopoulos, Schulze, Fischer, & Born, 2007) • REM and slow-wave (stages 3 & 4) important for learning to take place • Participants who completed a complex task and later dreamed about it subsequently performed better on the task than non-dreaming participants (Wamsley, Tucker, Payne, Benavides, & Stickgold, 2010) • Students spend more time in REM during exam periods
People Dream while Sleeping • Dreams: Products of an altered state of consciousness in which images and fantasies are confused with reality
REM Dreams and Non-REM Dreams • REM dreams: More likely to be bizarre and include intense emotions, visual and auditory hallucinations, and uncritical acceptance of illogical events • Non-REM dreams: Relatively dull (e.g., what sweater should I wear?)
REM Dreams and Non-REM Dreams Explanation: • Non-REM: General de-activation of many brain regions • REM: Brain structures associated with motivation, emotion, reward, vision are active; pre-frontal cortex is not