Chapter OneThe Major Issues

Biological Psychology

“study of the physiological, evolutionary, and developmental mechanisms of behavior and experience”

The Major Issues

The Mind-Brain Relationship

Biological Explanations of Behavior

Four categories

physiological-relates a behavior to the activity of the brain and other organs

ontogenetic-describes the development of the structure or behavior

evolutionary-examines a structure or a behavior in terms of evolutionary history

functional-describes why a structure or behavior evolved as it did

The Major Issues

The Mind-Brain Relationship

The Brain and Conscious Experience

Dualism

defined-the belief that mind and body are different kinds of substances, that exist independently but somehow interact

DesCartes-proposed that mind and brain interact in the pineal gland

The Major Issues

The Mind-Brain RelationshipThe Brain and Conscious Experience

Monismdefined-the belief that the universe consists of only one

kind of existenceForms of Monism

materialism-the view that everything that exists is material or physicalmentalism-the view that only the mind really existsidentity position-the view that mental processes

are the same thing as certain kinds of brain processes, but described in different terms

The Major Issues

The Mind-Brain Relationship

Discussions of Consciousness

David Chalmers-proposed distinguishing easy problems from hard problems

easy problems

pertain to many phenomena to which we apply the term consciousness

Ex: the difference between wakefulness and sleep, and the mechanisms that enable us to focus our attention

hard problem-the question of why and how any kind of brain activity is associated with consciousness

Nature or Nurture

The Genetics of BehaviorChromosome Structure

genes-units of heredity that maintain their structural identity from one generation to another

chromosomes-strands of genesdeoxyribonucleic acid-DNA-when it exists as a double strand

in a helix, it makes up a chromosome; when it exists in a single strand, it serves as a template for the synthesis of RNA

ribonucleic acid (RNA)-single strand chemical that can serve as a template for the synthesis of proteins

enzymes-biological catalysts that regulate chemical reactions in the body

Figure 1.6  How DNA controls development of the organismThe 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.

Nature or Nurture

Mendelian Genetics Cont’d

Patterns of Inheritancehomozygous-having an identical pair of genes on two

chromosomesheterozygous-having an unmatched pair of genes on two

chromosomesdominant gene-expressed in either the homozygous or

heterozygous condition (ex: Bb or BB will be expressed as “brown eyes”)

recessive gene-only expressed in the homozygous condition (ex: bb is the only condition where “blue eyes” will be expressed)

Figure 1.7  Four equally likely 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).

Nature and Nurture

Mendelian Genetics Cont’d

Patterns of Inheritance

Linkage and Crossing Over

Occurs when the inheritance of one gene is linked to inheritance of another gene

Occurs when a pair of chromosomes break apart and reconnect exchanging parts of each chromosome

Sex-Linked Genes

genes that are located on the sex chromosomes

an X-linked recessive gene will always be expressed in a male while a female will only express the gene if both of her X chromosomes carry the recessive gene

Nature and Nurture

Mendelian Genetics Cont’dPatterns of Inheritance

Sex-Limited Genespresent in both sexes but is expressed in only one sex, or has a much stronger effect in one sex than the otherthe genes do not need to be on the sex chromosomesthese genes are expressed only after activation by sex

hormonesSources of Variation

Recombination-some genes from one parent and some from the other, that combine to yield characteristics not found in either parentMutation-a random change in a single gene

Nature and Nurture

Heritability

defined-an estimate of how much of the variance in some characteristic within a population is due to heredity

Ranges from 0 to 1

If 0 then hereditary differences account for none of the observed variations in that characteristic

If 1 then hereditary differences account for all of the observed variations in that characteristic

Nature and Nurture Cont’d

How Heritability is DeterminedCompare similarities in monozygotic twins versus

dizygotic twinsCompare adopted children and their biological and

adoptive parentsCan heritability be modified?

PKU prevention as an example

Figure 1.8  Prenatal development of monozygotic and dizygotic twinsIn 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 more similar prenatal environments as well as more similar heredities.

The Evolution of Behavior

Evolution

Defined-change over generations in the frequencies of various genes in a population

How it occurs-Characteristics that lend themselves to survival assist an individual in surviving to reproductive age, therefore these “survival” genes are passed on to the next generation

Artificial Selection

Choosing individuals with a desired trait and making them the parents of the next generation

Video

Common Misunderstandings About Evolution

Does the use or disuse of some structure or behavior cause an evolutionary increase or decrease in that feature?

Have humans stopped evolving?

Does “evolution” mean “improvement”?

Does evolution act to benefit the individual or the species?

Sociobiology

Defined-studies the issues that concern the evolution of social behavior

It emphasizes functional explanations

Criticisms of the field

Functional explanations are often speculative

Sociobiological explanations sometimes imply that human behavior has evolved to be as it is, and therefore it should stay that

Use of Animals in Research

Reasons for Animal Research

The underlying mechanisms of behavior are similar across species and sometimes are easier to study in a nonhuman species

We are interested in animals for their own sake

What we learn about animals sheds light on human evolution

Certain experiments cannot use human subjects because of legal or ethical restrictions

Use of Animals in Research

The Ethical Debate

The range of opposition

minimalists-agree that some animal research is acceptable, but wish to minimize it

abolitionists-want all research on animals to stop

Prospects for Further Study

Researchers Associated with Biological psychologyBehavioral neuroscience-investigates how the function of the brain

and other organs influences behaviorNeuroscience-studies anatomy, physiology and biochemistry of the

nervous systemNeuropsychologist-conducts behavioral test to determine recovery

and deterioration after brain damage

Prospects for Further Study

Researchers associated with Biological Psychology Cont’dPsychophysiologist-measures heart rate, breathing rate, brain

waves and other body processes that change as a function of what someone is doing

Comparative psychologist-compares the behaviors of different species and tries to relate them to evolutionary histories and ecological niches

Sociobiologist-relates behaviors, especially social behaviors, to the function they have served, and therefore the presumed selective pressures that caused them to evolve

Prospects for Further Study

Medical Doctors

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