Mod 4 Part 2

1. Mod 4 Part 2 AP Psychology

2. Our Divided Brains • What is a split brain, and what does it reveal about brain functioning? • Previous belief that left hemisphere, where speech is located, was dominant • Splitting the Brain • Corpus Collosum: Wide band of axon fibers that connect the two hemispheres • Theory that uncontrollable epilepsy is caused by amplification of messages between the two hemispheres • Severing of corpus collosum sometimes used to conrol epilepsy • Seizures all but eliminated in split brain patients (Gazzaniga 1967)

3. Split Brain Studies • Optics • Optic nerves are wired to opposite visual area • Heart experiment (Gazzaniga 1967) • Identification of right visual field with speech and left visual field through pointing • Left hand doesn’t know what the right is doing • One buttoning, the other unbuttoning • Woman with stroke in corpus collosum kept getting strangled by left hand (Ramachandran and Blakeslee 1998) • Rock, paper, scissors? • One person of two minds • Alien hand syndrome (Feinberg 2001, Wilson 2002) • Unconscious mind can controll behavior • Left hemisphere acts as press agent and rationalizer (Gazzaniga 1988) • Unconscious mind like autopilot, but part of the brain reports and interprets behavior (Wegner 2001, Wilson 2002) • Right and left hemispheres can follow an order to simultaneously copy two different drawings (Franz et al 2000)

4. Studying Hemispheric differences in the intact brain • Perceptual tasks= right hemisphere • Speaking and calculating= left hemisphere • Doctors can put half of brain to sleep (Keenan 2001) • Left brain= person stops talking • Right brain= person has trouble recognizing altered self-image • Words more quickly understood if flashed in right visual field, picture more easily understood when flashed in left visual field. • Deaf people use left hemisphere to process sign language (Corina et al 1992, Hickok et al 2001) • Broca’s area important in signed and spoken language (Corina 1998) • Left understands literal interpretations and right makes subtle references (Beeman and Chiarello 1998, Beeman et al 1994, Bowden and Beeman 1998) • Right hemisphere helps modulate speech to make meaning clear (Heller 1990) • Babies use left side of mouth to smile and right side of mouth to babble

5. Brain Organization and Handedness • Right-handers (90%) process speech almost entirely in left hemisphere, which is larger (Springer and Deutsch 1995) • Dominant right handedness began early in evolution (Corballis 1998, Steele 2000) • 9 in 10 fetuses suck their right thumb • Most primates are more even, but chimps, gorillas, and humans favor righthandedness (Geschwind et al 2002, Hopkins et al 2001) • Identical twins do not necessarily share handedness (Halpern and Coren 1990) • 2/3 of babies lay with head to the right, almost all of these become right handed (Michel 1981) • Left handers are more likely to • Have reading difficulties (Geschwind and Behan 1984) • Be musicians, mathematicians, professional baseball players

6. The case of the disappearing Southpaw • Percentage of left handers declines dramatically with age (Coren 1993) • Being open to left handedness only increased number of left handers by 6% (Porac et al 1980) • Left Handers are more likely to (Halpern and Coren) • Experience birth stress like prematurity or need for assisted respiration • Have knee and joint problems • Have immune system problems • Die nine years earlier! • Factoring out children made the lifespan 6 years different (Aggleton et al 1993, Rgoerson 1994) • Follow-up research showed no life expectancy advantage to right handedness (Harris 1993) • At any age, left handers were no more likely to die (Salive et al 1993)

7. Reflections on the Biological Revolution in Psychology • Genes and experience influence personality, emotions, and intelligence • Brian development underlies a child’s mental development • Sense organs and brains allow us to see and hear • The brain records memories • Aberrant brain anatomy and chemistry influence depression and schizophrenia and biological treatments can alleviate symptoms • Brain and body work together to create experiences of hunger, sexuality, fear, sleep, and dreams • Mind and body influence vulnerability to disease and capacity to heal • Evolutionary history may influence us to hurt, help, or love certain others.

8. Stop and Review • What connects the two hemispheres of the brain? • How have researchers learned about the different functions of the two brain hemispheres? • Describe the finding of experiments with optics in split brain patients. • Which side of the brain is more logical and which side is more creative? • Give a hypothesis as to why left handedness is related to earlier death?

9. Review for Unit 3 Test • III. Biological Bases of Behavior (8–10%) • An effective introduction to the relationship between physiological processes and • behavior—including the influence of neural function, the nervous system and the • brain, and genetic contributions to behavior—is an important element in the AP • course. • AP students in psychology should be able to do the following: • • Identify basic processes and systems in the biological bases of behavior, • including parts of the neuron and the process of transmission of a signal • between neurons. • • Discuss the influence of drugs on neurotransmitters (e.g., reuptake • mechanisms). • • Discuss the effect of the endocrine system on behavior. • • Describe the nervous system and its subdivisions and functions: • — central and peripheral nervous systems; • — major brain regions, lobes, and cortical areas; • — brain lateralization and hemispheric specialization. • • Recount historic and contemporary research strategies and technologies that • support research (e.g., case studies, split-brain research, imaging techniques). • • Discuss psychology’s abiding interest in how heredity, environment, and • evolution work together to shape behavior. • • Predict how traits and behavior can be selected for their adaptive value. • • Identify key contributors (e.g., Paul Broca, Charles Darwin, Michael Gazzaniga, • Roger Sperry, Carl Wernicke).