lesson one

Chapter OneThe Major Issues

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James W. KalatBiological Psychology, 8th Edition

Chapter 1: The Major Issues

Biological Psychology

• Study of the physiological, evolutionary, and developmental mechanisms of behavior and experience– emphasis on the study of areas and sub-areas of the

brain– brain area’s function depends on communication among

neurons, the “building blocks of behavior”– neuron activity somehow produces behavior and

experience

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Figure 1.1 A dorsal view (from above) and a ventral view (from below) of the human brain. The brain has an enormous number of divisions and subareas; the labels point to a few of the main ones that are visible from outside.

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Biological Explanations of Behavior

• Physiological: relates a behavior to the activity of the brain and other organs (area of brain enables bird to sing)

• Ontogenetic: describes the development of the structure or behavior (why genes and environment both necessary for bird to sing)

• Evolutionary: examines a structure or a behavior in terms of evolutionary history (two different species of birds with similar songs have same ancestor)

• Functional: describes why a structure or behavior evolved as it did (singing improves bird’s chances of mating)

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Mind-Body Problem

• Dualism: mind and body are different kinds of substances, that exist independently but somehow interact– René Descartes proposed that mind and brain interact in

the pineal gland

• Monism: there is only one kind of existence– materialism: everything is material or physical– mentalism: only the mind exists– identity: mental processes are the same thing as certain

kinds of brain processes, but described in different terms (e.g., fear is the same as the accompanying pattern of neural activity in the brain)

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Mind-Body Problem cont.

• What is consciousness and how is it produced?

• Hard problem: the question of why and how any kind of brain activity is associated with consciousness– Chalmers (1995): consciousness is a fundamental

property of matter and cannot be reduced further

• Easy problems: determining the difference between wakefulness and sleep, or identifying brain mechanisms that enable us to focus our attention– Dennet (1991, 1996): When we answer all of the easy

problems, the hard problem will go away

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Mind-Body Problem cont.

• Research may not solve problem soon because consciousness is not directly observable– I know that I am conscious but I can only infer that you

have conscious experience– solipsism: the belief that only I exist

• Where and when does consciousness occur?– do all animals have conscious experiences? plants? rocks?– when does the human embryo experience consciousness?– could we build a robot that experiences consciousness?

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Genetics of Behavior

• Mendel (19th century): inheritance occurs through genes– chromosomes are strands of genes, normally in pairs – genes are units of heredity that maintain their structural

identity across generations– a genotype is an expression of a gene pair (e.g., BB, Bb,

or bb)• Deoxyribonucleic acid (DNA):

– when DNA exists as a double strand in a helix, it makes up a chromosome

– when DNA exists in a single strand, it serves as a template for the synthesis of RNA

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Figure 1.6 How DNA controls the development of an organism. The sequence of bases along a strand of DNA determines the order of bases along a strand of RNA; RNA in turn controls the sequence of amino acids in a protein molecule.

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Genetics of Behavior cont.

• Genotype expression (B=brown eyes; b=blue eyes)– homozygous: having an identical pair of genes on two

chromosomes (BB or bb)– heterozygous: having an unmatched pair of genes on two

chromosomes (Bb)– dominant gene: expressed in either the homozygous or

heterozygous condition (Bb or BB will be expressed as brown eyes)

– recessive gene: only expressed in the homozygous condition (bb is the only condition where blue eyes will be expressed)

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Figure 1.7 Four possible outcomes of a mating between parents who are heterozygous for a given gene (Tt). A child in this family has a 25% chance of being homozygous for the dominant gene (TT), a 25% chance of being homozygous for the recessive gene (tt), and a 50% chance of being heterozygous (Tt).

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• When genes are close together on the same chromosome they are usually inherited together, e.g., BC or bc– “crossing over” occurs during reproduction when a pair of

chromosomes exchange parts with each other, e.g., BC and bc become Bc and bC

• Sex-linked genes on X and Y chromosomes– male (XY) has only one X chromosome and will always

express X-linked recessive genes (8% have red-green color blindness)

– female (XX) will express a recessive gene only if it occurs on both of her X chromosomes (1% have color blindness)

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• Sex-limited genes– present in both sexes but effect is limited or almost limited

to one sex (chest hair, breast size)– genes expressed only after activation by sex hormones

• Sources of variation– recombination: some genes from two parents combine to

yield characteristics not found in either parent– mutation: a random change in a single gene– crossing over creates unique characteristics not found in

either parent

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• Heritability– an estimate of how much of the variance in a population

characteristic is due to heredity (ranges from 0 to 1)– if 0, heredity accounts for none of the observed variations

in that characteristic (e.g., in a population with similar genes, most differences are due to environment)

– if 1, heredity accounts for all of the variations in that characteristic (e.g., in identical environments most differences are due to genes)

– if 0.5, both components contribute

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• How heritability is determined– compare similarities in monozygotic twins versus

dizygotic twins– compare adopted children with their biological and

adoptive parents– findings support high heritability in many areas but we

may underestimate the effect of environment and interaction between geneotype and environment

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• Can heritability be modified?– PKU, caused by genetic inability to metabolize

phenylalanine, can be minimized with proper diet

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Figure 1.8 Prenatal development of monozygotic and dizygotic twins. In most cases, monozygotic (identical) twins develop in a single placenta and have the same blood supply. Dizygotic (fraternal) twins develop in separate placentas. Therefore, monozygotic twins have the sane prenatal environment as well as the same genetic inheritance, and dizygotic twins differ in both respects.

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Evolution of Behavior

• Change over generations in the frequencies of various genes in a population

• Change occurs through mutations, recombinations and any new genes that are successfully reproduced

• Artificial selection limits reproduction to animals that possess a desired trait, ensuring its survival

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Misunderstandings about Evolution

• “Lamarckian evolution” is mistaken belief that we acquire characteristics through use and lose them through disuse.

• If “survival of fittest” no longer applies, has evolution stopped? – no, reproduction, not survival is key

• Does evolution mean improvement? – maybe; your genes got you here but they may not be

advantageous tomorrow

• Does evolution act to benefit the individual or the species? – neither; it acts to spread the genes

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Sociobiology/Evolutionary Psychology

• Seeks functional explanations for why a behavior is useful and is favored by natural selection– why some animals have better color or peripheral vision– why we cycle through stages of sleep– why mammals and birds use most of their energy to stay

warm– why different species have different eating habits– why people die at different rates– why more men than women enjoy casual sex with multiple

partners

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Sociobiology/Evolutionary Psychology cont

• How does sociobiology explain altruistic behavior?– a gene that encourages altruism would help others survive

to reproduce– humans exhibit altruism but uncommon in non-humans– reciprocal altruism and kin selection may help spread

gene

• Sociobiology can be criticized when practitioners assume that a behavior is adaptive and then propose an explanation without testing it

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Reasons for Animal Research

• Underlying mechanisms of behavior are similar across species and sometimes a nonhuman species is easier to study

• We are interested in animals for their own sake

• Learning about animals sheds light on human evolution

• Legal or ethical restrictions prevent the use of human participants in certain experiments

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Figure 1.12 Brains of several species. The general plan and organization of the brain are similar for all mammals, even though brain size varies from species to species.

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The Ethical Debate on Animal Research

• Some experiments subject animals to brain damage, electrode implantation, injections for drugs or hormones

• Minimalists agree that some animal research is acceptable, but wish to minimize it

• Abolitionists want all research on animals to stop

• Principles of moderation and compromise are now the legal standard in the US

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Careers in Biological Psychology for Psychologists (PhDs)

• Behavioral neuroscientist: investigates how functioning of the brain and other organisms affect behavior

• Neuroscientist: studies anatomy, biochemistry, and physiology of the nervous system

• Neuropsychologist: conducts behavioral tests to determine what brain damaged people can and cannot do

• Psychophysiologist: measures heart rate, breathing rate brain waves, and other body processes that change as a function of people’s activities and information processing

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Careers in Biological Psychology for Physicians (MDs)

• Neurologist: treats people with brain damage or diseases of the brain

• Neurosurgeon: performs brain surgery

• Psychiatrist: helps people with emotional distress or troublesome behaviors, sometimes using drugs or other medical procedures

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lesson one

Documents

kalat biological psychology

major issues

edition chapter

biological psychology

brain brain areas function

brain mechanisms

human brain

bb heterozygous